Publications by authors named "Seiji Mizuno"

90 Publications

R3HDM1 haploinsufficiency is associated with mild intellectual disability.

Am J Med Genet A 2021 Mar 22. Epub 2021 Mar 22.

Department of Genetics, Institute for Developmental Research, Aichi Developmental Disability Center, Kasugai, Japan.

R3HDM1 (R3H domain containing 1) is an uncharacterized RNA-binding protein that is highly expressed in the human cerebral cortex. We report the first case of a 12-year-old Japanese male with haploinsufficiency of R3HDM1. He presented with mild intellectual disability (ID) and developmental delay. He had a pericentric inversion of 46,XY,inv(2)(p16.1q21.3)dn with breakpoints in intron 19 of R3HDM1 (2q21.3) and the intergenic region (2p16.1). The R3HDM1 levels in his lymphoblastoid cells were reduced to approximately half that of the healthy controls. However, the expression of MIR128-1, in intron 18 of R3HDM1, was not affected via the pericentric inversion. Knockdown of R3HDM1 in mouse embryonic hippocampal neurons suppressed dendritic growth and branching. Notably, the Database of Genomic Variants reported the case of a healthy control with a 488-kb deletion that included both R3HDM1 and MIR128-1. miR-128 has been reported to inhibit dendritic growth and branching in mouse brain neurons, which directly opposes the novel functions of R3HDM1. These findings suggest that deleting both R3HDM1 and MIR128-1 alleviates the symptoms of the disease caused by loss-of-function mutations in R3HDM1 only. Thus, haploinsufficiency of R3HDM1 in the patient may be the cause of the mild ID due to the genetic imbalance between R3HDM1 and MIR128-1.
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http://dx.doi.org/10.1002/ajmg.a.62173DOI Listing
March 2021

Clinical delineation, sex differences, and genotype-phenotype correlation in pathogenic KDM6A variants causing X-linked Kabuki syndrome type 2.

Genet Med 2021 Mar 5. Epub 2021 Mar 5.

Division of Evolution & Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.

Purpose: The variant spectrum and the phenotype of X-linked Kabuki syndrome type 2 (KS2) are poorly understood.

Methods: Genetic and clinical details of new and published individuals with pathogenic KDM6A variants were compiled and analyzed.

Results: Sixty-one distinct pathogenic KDM6A variants (50 truncating, 11 missense) from 80 patients (34 males, 46 females) were identified. Missense variants clustered in the TRP 2, 3, 7 and Jmj-C domains. Truncating variants were significantly more likely to be de novo. Thirteen individuals had maternally inherited variants and one had a paternally inherited variant. Neonatal feeding difficulties, hypoglycemia, postnatal growth retardation, poor weight gain, motor delay, intellectual disability (ID), microcephaly, congenital heart anomalies, palate defects, renal malformations, strabismus, hearing loss, recurrent infections, hyperinsulinism, seizures, joint hypermobility, and gastroesophageal reflux were frequent clinical findings. Facial features of over a third of patients were not typical for KS. Males were significantly more likely to be born prematurely, have shorter stature, and severe developmental delay/ID.

Conclusion: We expand the KDM6A variant spectrum and delineate the KS2 phenotype. We demonstrate that the variability of the KS2 phenotypic depends on sex and the variant type. We also highlight the overlaps and differences between the phenotypes of KS2 and KS1.
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http://dx.doi.org/10.1038/s41436-021-01119-8DOI Listing
March 2021

CDK19-related disorder results from both loss-of-function and gain-of-function de novo missense variants.

Genet Med 2021 Jan 25. Epub 2021 Jan 25.

Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan.

Purpose: To expand the recent description of a new neurodevelopmental syndrome related to alterations in CDK19.

Methods: Individuals were identified through international collaboration. Functional studies included autophosphorylation assays for CDK19 Gly28Arg and Tyr32His variants and in vivo zebrafish assays of the CDK19 and CDK19.

Results: We describe 11 unrelated individuals (age range: 9 months to 14 years) with de novo missense variants mapped to the kinase domain of CDK19, including two recurrent changes at residues Tyr32 and Gly28. In vitro autophosphorylation and substrate phosphorylation assays revealed that kinase activity of protein was lower for p.Gly28Arg and higher for p.Tyr32His substitutions compared with that of the wild-type protein. Injection of CDK19 messenger RNA (mRNA) with either the Tyr32His or the Gly28Arg variants using in vivo zebrafish model significantly increased fraction of embryos with morphological abnormalities. Overall, the phenotype of the now 14 individuals with CDK19-related disorder includes universal developmental delay and facial dysmorphism, hypotonia (79%), seizures (64%), ophthalmologic anomalies (64%), and autism/autistic traits (56%).

Conclusion: CDK19 de novo missense variants are responsible for a novel neurodevelopmental disorder. Both kinase assay and zebrafish experiments showed that the pathogenetic mechanism may be more diverse than previously thought.
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http://dx.doi.org/10.1038/s41436-020-01091-9DOI Listing
January 2021

Biallelic loss of OTUD7A causes severe muscular hypotonia, intellectual disability, and seizures.

Am J Med Genet A 2021 04 31;185(4):1182-1186. Epub 2020 Dec 31.

Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, Japan.

The heterozygous deletion of 15q13.3 is a recurrently observed microdeletion syndrome associated with a relatively mild phenotype including learning disability and language impairment. In contrast, the homozygous deletion of 15q13.3 is extremely rare and is associated with a much severer phenotype that includes epileptic encephalopathy, profound intellectual disability, and hypotonia. Which of the genes within the deleted interval is responsible for the more severe features when biallelically deleted is currently unknown. Here, we report a patient with profound hypotonia, severe intellectual disability, and seizures who had biallelic loss-of-function variants in OTUD7A: a 15q13.3 deletion including the OTUD7A locus, and a frameshift OTUD7A variant c.1125del, p.(Glu375Aspfs*11). Unexpectedly, both aberrations occurred de novo. Our experiment using Caenorhabditis elegans showed that worms carrying a corresponding homozygous variant in the homolog OTUB-2 exhibited weakened muscle contraction suggestive of aberrant neuromuscular transmission. We concluded that the biallelic complete loss of OTUD7A in humans represents a presumably new autosomal recessive disorder characterized by profound hypotonia, severe intellectual disability, and seizures.
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http://dx.doi.org/10.1002/ajmg.a.62054DOI Listing
April 2021

Legg-Calvé-Perthes disease in a patient with Bardet-Biedl syndrome: A case report of a novel mutation.

Clin Case Rep 2020 Dec 21;8(12):3110-3115. Epub 2020 Sep 21.

Department of Orthopaedic Surgery Aichi Children's Health and Medical Center Obu Japan.

This article reports a girl with Bardet-Biedl syndrome (BBS) having a novel causative mutation who developed Legg-Calvé-Perthes disease (LCPD). There exists a possibility that the prognosis of LCPD had been adversely affected by the concomitant BBS.
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http://dx.doi.org/10.1002/ccr3.3357DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7752338PMC
December 2020

Digenic mutations in and impair formaldehyde clearance and cause a multisystem disorder, AMeD syndrome.

Sci Adv 2020 Dec 18;6(51). Epub 2020 Dec 18.

Department of Genetics, Research Institute of Environmental Medicine (RIeM), Nagoya University, Nagoya, Japan.

Rs671 in the aldehyde dehydrogenase 2 gene () is the cause of Asian alcohol flushing response after drinking. ALDH2 detoxifies endogenous aldehydes, which are the major source of DNA damage repaired by the Fanconi anemia pathway. Here, we show that the rs671 defective allele in combination with mutations in the alcohol dehydrogenase 5 gene, which encodes formaldehyde dehydrogenase ( ), causes a previously unidentified disorder, AMeD (aplastic anemia, mental retardation, and dwarfism) syndrome. Cellular studies revealed that a decrease in the formaldehyde tolerance underlies a loss of differentiation and proliferation capacity of hematopoietic stem cells. Moreover, double-deficient mice recapitulated key clinical features of AMeDS, showing short life span, dwarfism, and hematopoietic failure. Collectively, our results suggest that the combined deficiency of formaldehyde clearance mechanisms leads to the complex clinical features due to overload of formaldehyde-induced DNA damage, thereby saturation of DNA repair processes.
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http://dx.doi.org/10.1126/sciadv.abd7197DOI Listing
December 2020

A novel missense variant in CUL3 shows altered binding ability to BTB-adaptor proteins leading to diverse phenotypes of CUL3-related disorders.

J Hum Genet 2020 Oct 31. Epub 2020 Oct 31.

Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.

CUL3 forms Cullin-Ring ubiquitin ligases (CRL) with Ring-box protein and BTB-adaptor proteins. A variety of BTB-adaptor proteins have been reported to interact with the N-terminus of CUL3, which makes it possible to recognize various substrates for degradation. Regarding the association of CUL3 with neurodevelopmental disorders, a recent study reported three patients with global developmental delay, who carried de novo variants in CUL3. Here, we describe a novel de novo CUL3 variant (c.158G > A, p.Ser53Asn) identified in a patient with global developmental delay, who presented some novel dysmorphic features, including macrocephaly, characteristic facial features, and cutis marmorata. Immunoprecipitation and immunoblot analyses identified significantly weaker binding ability to some BTB proteins in CUL3-S53N compared to wild-type. Interestingly, label-free quantification proteomics analysis of samples immunoprecipitated by CUL3-S53N showed a significantly decreased interaction with some BTB proteins, while almost equal interaction or significantly increased interaction was observed with other BTB proteins. The binding between CUL3 and BTB proteins is essential for CRL substrate recognition, and alteration of their interaction is thought to result in the quantitative alteration in substrate proteins. It is possible that the difference of dysmorphic features between the present case and previously reported cases is caused by the distinctive effect of each CUL3 variant on substrate proteins. The clinical information of the present case will expand the picture of CUL3-related global developmental disorders, and subsequent cell biological analysis of the novel mutation will provide insight into the underlying molecular mechanism of how CUL3 pathogenic variants cause neurological disorders.
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http://dx.doi.org/10.1038/s10038-020-00868-9DOI Listing
October 2020

Role of chimeric transcript formation in the pathogenesis of birth defects.

Congenit Anom (Kyoto) 2020 Oct 28. Epub 2020 Oct 28.

Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan.

Chimeric transcripts are formed by chromosomal aberrations. Little is known about the role of chimeric transcripts in the pathogenesis of birth defects. We reanalyzed RNA-seq data in alignment map files from the peripheral blood of 56 patients in whom the diagnoses could not be confirmed by standard exome analysis and transcriptome analysis to screen for chimeric transcripts using a dedicated software, ChimPipe. Chimeric analysis led to a diagnosis in two of the 56 patients: (a) the first patient had a chimeric transcript spanning the causative gene ZEB2 and the GTDC1 gene in its neighboring locus. RNA-seq revealed reads spanning exon 5 of ZEB2 and exon 7 of GTDC1. Whole genome sequencing revealed a 436-kb deletion spanning intron 4 of ZEB2 and intron 7 of GTDC1 and the diagnosis of Mowat-Wilson syndrome was made. (b) The second patient had a chimeric transcript spanning the causative gene KCNK9 and the TRAPPC9 gene in its neighboring locus. RNA-seq revealed reads spanning exon 21 of TRAPPC9 and exon 1 of KCNK9. Whole genome sequencing revealed a 186-kb deletion spanning intron 20 of TRAPPC9 and intron 1 of KCNK9 in this patient. KCNK9 gene is a maternally expressed imprinted gene. The diagnosis of Birk-Barel syndrome was made. Thus, both patients had chimeric transcripts that were directly involved in the pathogenesis of the birth defects. The approach reported herein, of detecting chimeric transcripts from RNA-seq data, is unique in that the approach does not rely on any prior information on the presence of genomic deletion.
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http://dx.doi.org/10.1111/cga.12400DOI Listing
October 2020

Expanding the phenotype of biallelic loss-of-function variants in the NSUN2 gene: Description of four individuals with juvenile cataract, chronic nephritis, or brain anomaly as novel complications.

Am J Med Genet A 2021 01 20;185(1):282-285. Epub 2020 Oct 20.

Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.

The NSUN2 gene encodes a tRNA cytosine methyltransferase that functions in the maturation of leucyl tRNA (Leu) (CAA) precursors, which is crucial for the anticodon-codon pairing and correct translation of mRNA. Biallelic loss of function variants in NSUN2 are known to cause moderate to severe intellectual disability. Microcephaly, postnatal growth retardation, and dysmorphic facial features are common complications in this genetic disorder, and delayed puberty is occasionally observed. Here, we report four individuals, two sets of siblings, with biallelic loss-of-function variants in the NSUN2 gene. The first set of siblings have compound heterozygous frameshift variants: c.546_547insCT, p.Met183Leufs*13; c.1583del, p.Pro528Hisfs*19, and the other siblings carry a homozygous frameshift variant: c.1269dup, p.Val424Cysfs*14. In addition to previously reported clinical features, the first set of siblings showed novel complications of juvenile cataract and chronic nephritis. The other siblings showed hypomyelination and simplified gyral pattern in neuroimaging. NSUN2-related intellectual disability is a very rare condition, and less than 20 cases have been reported previously. Juvenile cataract, chronic nephritis, and brain anomaly shown in the present patients have not been previously described. Our report suggests clinical diversity of NSUN2-related intellectual disability.
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http://dx.doi.org/10.1002/ajmg.a.61927DOI Listing
January 2021

Gait characteristics of children with Williams syndrome with impaired visuospatial recognition: a three-dimensional gait analysis study.

Exp Brain Res 2020 Dec 14;238(12):2887-2895. Epub 2020 Oct 14.

Department of Pediatrics, Okazaki Medical Center for Child Development, Aichi, Japan.

Williams syndrome (WS) is a genetically based neurodevelopmental disorder characterized by intellectual disability and impaired visuospatial recognition. The aim of this study was to analyze the gait characteristics of WS children with impaired visuospatial recognition using a three-dimensional gait analysis (3DGA) to clarify the gait adaptation needed to compensate for it. 3DGA was performed in 8 WS children with impaired visuospatial recognition (mean age, 11.8 years) and 9 age-, sex-, height-, and weight-matched controls. Clinical data, fundamental motor tests, and gait variables while walking on a flat surface and walking up a mat were compared between the two groups, and the correlations between variables were analyzed in the WS children. WS children showed impairment of balance function without muscle weakness. In walking on a flat surface, the WS group showed reduced walking speed, short step length, increased variability of step length, increased knee flexion throughout the stance phase, increased horizontal pelvic range of motion (ROM), and a low Gait Deviation Index and a high Gait Profile Score, which are indices of gait quality. In walking up a mat, the WS group showed further reduced walking speed and decreased sagittal hip flexion and ankle dorsiflexion ROM in the swing phase. Impaired balance function was significantly correlated with increased variability of step length and decreased sagittal ankle dorsiflexion ROM in the swing phase. The detailed gait pattern of WS children with impaired visuospatial recognition was presented. These findings show that impaired visuospatial recognition and balance function contribute to gait adaptation.
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http://dx.doi.org/10.1007/s00221-020-05946-0DOI Listing
December 2020

Mowat-Wilson syndrome: growth charts.

Orphanet J Rare Dis 2020 06 15;15(1):151. Epub 2020 Jun 15.

Medical Genetics Unit, Department of Mother and Child, Azienda Unità Sanitaria Locale - IRCCS di Reggio Emilia, Viale Risorgimento, 80 42123, Reggio Emilia, Italy.

Background: Mowat-Wilson syndrome (MWS; OMIM #235730) is a genetic condition caused by heterozygous mutations or deletions of the ZEB2 gene. It is characterized by moderate-severe intellectual disability, epilepsy, Hirschsprung disease and multiple organ malformations of which congenital heart defects and urogenital anomalies are the most frequent ones. To date, a clear description of the physical development of MWS patients does not exist. The aim of this study is to provide up-to-date growth charts specific for infants and children with MWS. Charts for males and females aged from 0 to 16 years were generated using a total of 2865 measurements from 99 MWS patients of different ancestries. All data were collected through extensive collaborations with the Italian MWS association (AIMW) and the MWS Foundation. The GAMLSS package for the R statistical computing software was used to model the growth charts. Height, weight, body mass index (BMI) and head circumference were compared to those from standard international growth charts for healthy children.

Results: In newborns, weight and length were distributed as in the general population, while head circumference was slightly smaller, with an average below the 30th centile. Up to the age of 7 years, weight and height distribution was shifted to slightly lower values than in the general population; after that, the difference increased further, with 50% of the affected children below the 5th centile of the general population. BMI distribution was similar to that of non-affected children until the age of 7 years, at which point values in MWS children increased with a less steep slope, particularly in males. Microcephaly was sometimes present at birth, but in most cases it developed gradually during infancy; many children had a small head circumference, between the 3rd and the 10th centile, rather than being truly microcephalic (at least 2 SD below the mean). Most patients were of slender build.

Conclusions: These charts contribute to the understanding of the natural history of MWS and should assist pediatricians and other caregivers in providing optimal care to MWS individuals who show problems related to physical growth. This is the first study on growth in patients with MWS.
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http://dx.doi.org/10.1186/s13023-020-01418-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7294656PMC
June 2020

The involvement of U-type dicentric chromosomes in the formation of terminal deletions with or without adjacent inverted duplications.

Hum Genet 2020 Nov 2;139(11):1417-1427. Epub 2020 Jun 2.

Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.

An inverted duplication with a terminal deletion (inv-dup-del) is one of the complex constitutional structural rearrangements that can occur in a chromosome. Although breakages of dicentric chromosome have been suggested, the precise mechanism of this is yet to be fully understood. In our present study, we investigated the genomic structure of 10 inv-dup-del cases to elucidate this mechanism. Two recurrent 8p inv-dup-del cases harbored a large copy-number-neutral region between the duplication and deletion in common. Although the other non-recurrent cases did not appear to have this copy-number-neutral region, refined sequencing analysis identified that they contained a small intervening region at the junction between the inverted and non-inverted segment. The size of this small intervening region ranged from 1741 to 3728 bp. Combined with a presence of microhomology at the junction, a resolution of the replication fork stalling through template switching within the same replication fork is suggested. We further observed two cases with mosaicism of the dicentric chromosome and various structural rearrangements related to the dicentric chromosome. Refined analysis allowed us to identify different breakpoints on the same chromosome in the same case, implicating multiple rounds of U-type formation and its breakage. From these results, we propose that a replication-based mechanism generates unstable dicentric chromosomes and that their breakage leads to the formation of inv-dup-dels and other related derivative chromosomes.
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http://dx.doi.org/10.1007/s00439-020-02186-8DOI Listing
November 2020

Analysis of the Origin of Double Mosaic Aneuploidy in Two Cases.

Cytogenet Genome Res 2020 4;160(3):118-123. Epub 2020 Apr 4.

We present 2 cases of double mosaic aneuploidy harboring 2 or more different aneuploid cell lines, but no line with a normal chromosome constitution. One of these cases presented mosaicism of sex chromosome aneuploid cell lines (47,XXX/45,X) along with another line containing an autosomal trisomy (47,XX,+8), while the other case showed mosaicism of 2 different autosomal trisomy cell lines (47,XY,+5 and 47,XY,+8). To elucidate the mechanisms underlying these mosaicisms, we conducted molecular cytogenetic analyses. Genotyping data from the SNP microarray indicated that 2 sequential meiotic or early postzygotic segregation errors likely had occurred followed by natural selection. These cases suggest that frequent segregation errors and selection events in the meiotic and early postzygotic stages lead to this condition.
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http://dx.doi.org/10.1159/000507177DOI Listing
June 2020

Missense Mutations in NKAP Cause a Disorder of Transcriptional Regulation Characterized by Marfanoid Habitus and Cognitive Impairment.

Am J Hum Genet 2019 11 3;105(5):987-995. Epub 2019 Oct 3.

Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Laboratory of Rare Disease Research, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo 113-8657, Japan. Electronic address:

NKAP is a ubiquitously expressed nucleoplasmic protein that is currently known as a transcriptional regulatory molecule via its interaction with HDAC3 and spliceosomal proteins. Here, we report a disorder of transcriptional regulation due to missense mutations in the X chromosome gene, NKAP. These mutations are clustered in the C-terminal region of NKAP where NKAP interacts with HDAC3 and post-catalytic spliceosomal complex proteins. Consistent with a role for the C-terminal region of NKAP in embryogenesis, nkap mutant zebrafish with a C-terminally truncated NKAP demonstrate severe developmental defects. The clinical features of affected individuals are highly conserved and include developmental delay, hypotonia, joint contractures, behavioral abnormalities, Marfanoid habitus, and scoliosis. In affected cases, transcriptome analysis revealed the presence of a unique transcriptome signature, which is characterized by the downregulation of long genes with higher exon numbers. These observations indicate the critical role of NKAP in transcriptional regulation and demonstrate that perturbations of the C-terminal region lead to developmental defects in both humans and zebrafish.
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http://dx.doi.org/10.1016/j.ajhg.2019.09.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6848994PMC
November 2019

Genetic abnormalities in a large cohort of Coffin-Siris syndrome patients.

J Hum Genet 2019 Dec 17;64(12):1173-1186. Epub 2019 Sep 17.

Department of Human Genetics, Graduate school of medicine, Yokohama City University, Yokohama, Japan.

Coffin-Siris syndrome (CSS, MIM#135900) is a congenital disorder characterized by coarse facial features, intellectual disability, and hypoplasia of the fifth digit and nails. Pathogenic variants for CSS have been found in genes encoding proteins in the BAF (BRG1-associated factor) chromatin-remodeling complex. To date, more than 150 CSS patients with pathogenic variants in nine BAF-related genes have been reported. We previously reported 71 patients of whom 39 had pathogenic variants. Since then, we have recruited an additional 182 CSS-suspected patients. We performed comprehensive genetic analysis on these 182 patients and on the previously unresolved 32 patients, targeting pathogenic single nucleotide variants, short insertions/deletions and copy number variations (CNVs). We confirmed 78 pathogenic variations in 78 patients. Pathogenic variations in ARID1B, SMARCB1, SMARCA4, ARID1A, SOX11, SMARCE1, and PHF6 were identified in 48, 8, 7, 6, 4, 1, and 1 patients, respectively. In addition, we found three CNVs including SMARCA2. Of particular note, we found a partial deletion of SMARCB1 in one CSS patient and we thoroughly investigated the resulting abnormal transcripts.
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http://dx.doi.org/10.1038/s10038-019-0667-4DOI Listing
December 2019

A Syndromic Neurodevelopmental Disorder Caused by Mutations in SMARCD1, a Core SWI/SNF Subunit Needed for Context-Dependent Neuronal Gene Regulation in Flies.

Am J Hum Genet 2019 04 14;104(4):596-610. Epub 2019 Mar 14.

Centre Hospitalier Universitaire Sainte-Justine Research Center, University of Montreal, Montreal, QC H3T 1C5, Canada; Department of Pediatrics, University of Montreal, Montreal, QC H4A 3J1, Canada. Electronic address:

Mutations in several genes encoding components of the SWI/SNF chromatin remodeling complex cause neurodevelopmental disorders (NDDs). Here, we report on five individuals with mutations in SMARCD1; the individuals present with developmental delay, intellectual disability, hypotonia, feeding difficulties, and small hands and feet. Trio exome sequencing proved the mutations to be de novo in four of the five individuals. Mutations in other SWI/SNF components cause Coffin-Siris syndrome, Nicolaides-Baraitser syndrome, or other syndromic and non-syndromic NDDs. Although the individuals presented here have dysmorphisms and some clinical overlap with these syndromes, they lack their typical facial dysmorphisms. To gain insight into the function of SMARCD1 in neurons, we investigated the Drosophila ortholog Bap60 in postmitotic memory-forming neurons of the adult Drosophila mushroom body (MB). Targeted knockdown of Bap60 in the MB of adult flies causes defects in long-term memory. Mushroom-body-specific transcriptome analysis revealed that Bap60 is required for context-dependent expression of genes involved in neuron function and development in juvenile flies when synaptic connections are actively being formed in response to experience. Taken together, we identify an NDD caused by SMARCD1 mutations and establish a role for the SMARCD1 ortholog Bap60 in the regulation of neurodevelopmental genes during a critical time window of juvenile adult brain development when neuronal circuits that are required for learning and memory are formed.
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http://dx.doi.org/10.1016/j.ajhg.2019.02.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6451697PMC
April 2019

SATB2-associated syndrome in patients from Japan: Linguistic profiles.

Am J Med Genet A 2019 06 7;179(6):896-899. Epub 2019 Mar 7.

Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan.

Cleft palate can be classified as either syndromic or nonsyndromic. SATB2-associated syndrome is one example of a syndromic cleft palate that is accompanied by intellectual disability, and various dental anomalies. SATB2-associated syndrome can be caused by several different molecular mechanisms including intragenic mutations and deletions of SATB2. Here, we report two patients with SATB2 truncating mutations (p.Arg239* and p.Asp702Thrfs*38) and one with a 4.4 megabase deletion including the SATB2 locus. All three patients had cleft palate and other dysmorphic features including macrodontia wide diastema. None of the three patients had acquired any meaningful words at the age of 5 years. In a review of the linguistic natural history of presently reported three patients and 30 previously reported patients, only two patients had attained verbal skills beyond speaking a few words. This degree of delayed speech contrasts with that observed in the prototypic form of syndromic cleft palate, 22q11.2 deletion syndrome. The recognition of SATB2-associated syndrome prior to palatoplasty would be important for plastic surgeons and the families of patients because precise diagnosis should provide predictive information regarding the future linguistic and intellectual abilities of the patients. Macrodontia with a wide diastema and cleft palate is a helpful and highly suggestive sign for the diagnosis of SATB2-associated syndrome.
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http://dx.doi.org/10.1002/ajmg.a.61114DOI Listing
June 2019

Correction: The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

Authors:
Pleuntje J van der Sluijs Sandra Jansen Samantha A Vergano Miho Adachi-Fukuda Yasemin Alanay Adila AlKindy Anwar Baban Allan Bayat Stefanie Beck-Wödl Katherine Berry Emilia K Bijlsma Levinus A Bok Alwin F J Brouwer Ineke van der Burgt Philippe M Campeau Natalie Canham Krystyna Chrzanowska Yoyo W Y Chu Brain H Y Chung Karin Dahan Marjan De Rademaeker Anne Destree Tracy Dudding-Byth Rachel Earl Nursel Elcioglu Ellen R Elias Christina Fagerberg Alice Gardham Blanca Gener Erica H Gerkes Ute Grasshoff Arie van Haeringen Karin R Heitink Johanna C Herkert Nicolette S den Hollander Denise Horn David Hunt Sarina G Kant Mitsuhiro Kato Hülya Kayserili Rogier Kersseboom Esra Kilic Malgorzata Krajewska-Walasek Kylin Lammers Lone W Laulund Damien Lederer Melissa Lees Vanesa López-González Saskia Maas Grazia M S Mancini Carlo Marcelis Francisco Martinez Isabelle Maystadt Marianne McGuire Shane McKee Sarju Mehta Kay Metcalfe Jeff Milunsky Seiji Mizuno John B Moeschler Christian Netzer Charlotte W Ockeloen Barbara Oehl-Jaschkowitz Nobuhiko Okamoto Sharon N M Olminkhof Carmen Orellana Laurent Pasquier Caroline Pottinger Vera Riehmer Stephen P Robertson Maian Roifman Caroline Rooryck Fabienne G Ropers Monica Rosello Claudia A L Ruivenkamp Mahmut S Sagiroglu Suzanne C E H Sallevelt Amparo Sanchis Calvo Pelin O Simsek-Kiper Gabriela Soares Lucia Solaeche Fatma Mujgan Sonmez Miranda Splitt Duco Steenbeek Alexander P A Stegmann Constance T R M Stumpel Saori Tanabe Eyyup Uctepe G Eda Utine Hermine E Veenstra-Knol Sunita Venkateswaran Catheline Vilain Catherine Vincent-Delorme Anneke T Vulto-van Silfhout Patricia Wheeler Golder N Wilson Louise C Wilson Bernd Wollnik Tomoki Kosho Dagmar Wieczorek Evan Eichler Rolph Pfundt Bert B A de Vries Jill Clayton-Smith Gijs W E Santen

Genet Med 2019 Sep;21(9):2160-2161

Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.

The original version of this Article contained an error in the spelling of the author Pleuntje J. van der Sluijs, which was incorrectly given as Eline (P. J.) van der Sluijs. This has now been corrected in both the PDF and HTML versions of the Article.
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http://dx.doi.org/10.1038/s41436-018-0368-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752317PMC
September 2019

Delineation of LZTR1 mutation-positive patients with Noonan syndrome and identification of LZTR1 binding to RAF1-PPP1CB complexes.

Hum Genet 2019 Jan 27;138(1):21-35. Epub 2018 Oct 27.

Department of Medical Genetics, Tohoku University School of Medicine, 1-1 Seiryomachi, Aobaku, Sendai, 980-8574, Japan.

RASopathies are a group of developmental disorders caused by mutations in genes that regulate the RAS/MAPK pathway and include Noonan syndrome (NS), Costello syndrome, cardiofaciocutaneous syndrome and other related disorders. Whole exome sequencing studies recently identified LZTR1, PPP1CB and MRAS as new causative genes in RASopathies. However, information on the phenotypes of LZTR1 mutation-positive patients and functional properties of the mutations are limited. To identify variants of LZTR1, PPP1CB, and MRAS, we performed a targeted next-generation sequencing and reexamined previously analyzed exome data in 166 patients with suspected RASopathies. We identified eight LZTR1 variants, including a de novo variant, in seven probands who were suspicious for NS and one known de novo PPP1CB variant in a patient with NS. One of the seven probands had two compound heterozygous LZTR1 variants, suggesting autosomal recessive inheritance. All probands with LZTR1 variants had cardiac defects, including hypertrophic cardiomyopathy and atrial septal defect. Five of the seven probands had short stature or intellectual disabilities. Immunoprecipitation of endogenous LZTR1 followed by western blotting showed that LZTR1 bound to the RAF1-PPP1CB complex. Cells transfected with a small interfering RNA against LZTR1 exhibited decreased levels of RAF1 phosphorylated at Ser259. These are the first results to demonstrate LZTR1 in association with the RAF1-PPP1CB complex as a component of the RAS/MAPK pathway.
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http://dx.doi.org/10.1007/s00439-018-1951-7DOI Listing
January 2019

The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

Authors:
Pleuntje J van der Sluijs Sandra Jansen Samantha A Vergano Miho Adachi-Fukuda Yasemin Alanay Adila AlKindy Anwar Baban Allan Bayat Stefanie Beck-Wödl Katherine Berry Emilia K Bijlsma Levinus A Bok Alwin F J Brouwer Ineke van der Burgt Philippe M Campeau Natalie Canham Krystyna Chrzanowska Yoyo W Y Chu Brain H Y Chung Karin Dahan Marjan De Rademaeker Anne Destree Tracy Dudding-Byth Rachel Earl Nursel Elcioglu Ellen R Elias Christina Fagerberg Alice Gardham Blanca Gener Erica H Gerkes Ute Grasshoff Arie van Haeringen Karin R Heitink Johanna C Herkert Nicolette S den Hollander Denise Horn David Hunt Sarina G Kant Mitsuhiro Kato Hülya Kayserili Rogier Kersseboom Esra Kilic Malgorzata Krajewska-Walasek Kylin Lammers Lone W Laulund Damien Lederer Melissa Lees Vanesa López-González Saskia Maas Grazia M S Mancini Carlo Marcelis Francisco Martinez Isabelle Maystadt Marianne McGuire Shane McKee Sarju Mehta Kay Metcalfe Jeff Milunsky Seiji Mizuno John B Moeschler Christian Netzer Charlotte W Ockeloen Barbara Oehl-Jaschkowitz Nobuhiko Okamoto Sharon N M Olminkhof Carmen Orellana Laurent Pasquier Caroline Pottinger Vera Riehmer Stephen P Robertson Maian Roifman Caroline Rooryck Fabienne G Ropers Monica Rosello Claudia A L Ruivenkamp Mahmut S Sagiroglu Suzanne C E H Sallevelt Amparo Sanchis Calvo Pelin O Simsek-Kiper Gabriela Soares Lucia Solaeche Fatma Mujgan Sonmez Miranda Splitt Duco Steenbeek Alexander P A Stegmann Constance T R M Stumpel Saori Tanabe Eyyup Uctepe G Eda Utine Hermine E Veenstra-Knol Sunita Venkateswaran Catheline Vilain Catherine Vincent-Delorme Anneke T Vulto-van Silfhout Patricia Wheeler Golder N Wilson Louise C Wilson Bernd Wollnik Tomoki Kosho Dagmar Wieczorek Evan Eichler Rolph Pfundt Bert B A de Vries Jill Clayton-Smith Gijs W E Santen

Genet Med 2019 06 8;21(6):1295-1307. Epub 2018 Nov 8.

Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.

Purpose: Pathogenic variants in ARID1B are one of the most frequent causes of intellectual disability (ID) as determined by large-scale exome sequencing studies. Most studies published thus far describe clinically diagnosed Coffin-Siris patients (ARID1B-CSS) and it is unclear whether these data are representative for patients identified through sequencing of unbiased ID cohorts (ARID1B-ID). We therefore sought to determine genotypic and phenotypic differences between ARID1B-ID and ARID1B-CSS. In parallel, we investigated the effect of different methods of phenotype reporting.

Methods: Clinicians entered clinical data in an extensive web-based survey.

Results: 79 ARID1B-CSS and 64 ARID1B-ID patients were included. CSS-associated dysmorphic features, such as thick eyebrows, long eyelashes, thick alae nasi, long and/or broad philtrum, small nails and small or absent fifth distal phalanx and hypertrichosis, were observed significantly more often (p < 0.001) in ARID1B-CSS patients. No other significant differences were identified.

Conclusion: There are only minor differences between ARID1B-ID and ARID1B-CSS patients. ARID1B-related disorders seem to consist of a spectrum, and patients should be managed similarly. We demonstrated that data collection methods without an explicit option to report the absence of a feature (such as most Human Phenotype Ontology-based methods) tended to underestimate gene-related features.
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http://dx.doi.org/10.1038/s41436-018-0330-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752273PMC
June 2019

Maternal Uniparental Disomy for Chromosome 20: Physical and Endocrinological Characteristics of Five Patients.

J Clin Endocrinol Metab 2018 06;103(6):2083-2088

Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.

Context: Maternal uniparental disomy for chromosome 20 [UPD(20)mat], resulting in aberrant expression of imprinted transcripts at the GNAS locus, is a poorly characterized condition. These patients manifested a phenotype similar to that of Silver-Russell syndrome (SRS) and small for gestational age-short stature (SGA-SS); however, the etiological relationship between UPD(20)mat and SRS/SGA-SS remains unclear. Moreover, no report has described endocrinological assessment of UPD(20)mat patients, although paternal UPD(20), the mirror image entity of UPD(20)mat, is known to cause multiple hormone resistance reflecting reduced α-subunit of the stimulatory G protein expression.

Participants: Patients 1 to 5 showed nonmosaic heterodisomy and/or isodisomy for the entire chromosome 20. Patients 1 to 3 and 4 were identified through UPD(20)mat screening for 55 patients with etiology-unknown SRS and 96 patients with SGA-SS, respectively. Patient 5 was identified through molecular analysis for patients with developmental defects. Patients 1 to 5 manifested postnatal growth failure and feeding problems, with or without developmental delay, and other clinical features. Patients 1 to 4 were born SGA. Patients 4 and 5 exhibited hypercalcemia and low or low-normal parathyroid hormone levels. Patient 1 showed constantly decreased thyroid-stimulating hormone (TSH) levels after 12 years of age, although she had a normal TSH level at 5.2 years of age.

Conclusion: The results suggest that UPD(20)mat underlies growth failure and feeding problems with additional features and could account for >5% of etiology-unknown SRS and small percentages of SGA-SS. Most important, this study provides an indication that UPD(20)mat can be associated with hypersensitivity of hormone receptors, which may gradually develop with age.
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http://dx.doi.org/10.1210/jc.2017-02780DOI Listing
June 2018

Distinctive facies, macrocephaly, and developmental delay are signs of a PTEN mutation in childhood.

Brain Dev 2018 Sep 8;40(8):678-684. Epub 2018 May 8.

Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-Cho, Mizuho-Ku, Nagoya 467-8601, Japan. Electronic address:

Background: Germline mutations of the PTEN gene are responsible for several PTEN hamartoma tumor syndromes. They are also implicated as a cause of macrocephaly and mild to severe developmental delay, regardless of the presence or absence of hamartomas in childhood. Nevertheless, because of limited information, the clinical features present during childhood in patients with a PTEN mutation are yet to be elucidated.

Methods: PTEN mutations were investigated by multiplex targeted sequencing of genomic DNA from 33 children with increased head circumference (>+2 SD) and developmental delay. The clinical features of all the patients with a PTEN mutation were abstracted by dysmorphologists.

Results: We have identified six children with a PTEN mutation. Clinical dissection of these six patients, in addition to patient reports in the literature, revealed distinctive facial features that included frontal bossing, dolichocephaly, horizontal eyebrows, and a depressed nasal bridge. Macrocephaly (+3.2 to +6.0 SD) was noticeable compared to their height (-0.8 to +2.1 SD), and the difference in the SD value of head circumference and height was more than 3 SD in all patients.

Conclusion: The presence of distinctive facies, extreme macrocephaly with normal to mildly high stature, and developmental delay may be useful for identifying patients with a PTEN mutation in childhood. Early identification of patients with a PTEN mutation would help uncover the natural course of tumor development in this group of individuals who have a possible predisposition to cancer, and be important for the development of an optimal surveillance strategy.
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http://dx.doi.org/10.1016/j.braindev.2018.04.008DOI Listing
September 2018

Clinical and genetic characterization of a patient with SOX5 haploinsufficiency caused by a de novo balanced reciprocal translocation.

Gene 2018 May 22;655:65-70. Epub 2018 Mar 22.

Department of Genetics, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, Japan; Department of Neurology, Neurology and Stroke Center, Takamatsu Municipal Hospital, Takamatsu, Kagawa, Japan. Electronic address:

Lamb-Shaffer syndrome (OMIM: 616803) is a neurodevelopmental disorder characterized by developmental delay, mild to moderate intellectual disability, speech delay, and mild characteristic facial appearance caused by SOX5 haploinsufficiency on chromosome 12p12.1. There are clinical variabilities among the patients with genomic alterations, such as intragenic deletions, a point mutation, and a chromosomal translocation of t(11;12)(p13;p12.1), in SOX5. We report herein a 5-year-old Japanese male with a de novo balanced reciprocal translocation t(12;20)(p12.1;p12.3) presenting a mild intellectual disability, speech delay, characteristic facial appearance, and autistic features. We determined the translocation breakpoints of the patient to be in intron 4 of SOX5 and the intergenic region in 20p12.3 via FISH and nucleotide sequence analyses. Thus, the present patient has SOX5 haploinsufficiency affecting 2 long forms of SOX5 and is the second reported case of Lamb-Shaffer syndrome caused by a de novo balanced reciprocal translocation. This report confirmed that haploinsufficiency of the 2 long forms of SOX5 presents common clinical features, including mild intellectual disability and autistic features, which could be useful for the clinical diagnosis of Lamb-Shaffer syndrome.
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http://dx.doi.org/10.1016/j.gene.2018.02.049DOI Listing
May 2018

Growth pattern of Rahman syndrome.

Am J Med Genet A 2018 03 31;176(3):712-714. Epub 2018 Jan 31.

Department of Pediatrics, Central Hospital, Aichi Human Service Center, Aichi, Japan.

Recently, in a cohort study with "overgrowth syndrome with intellectual disability," five subjects were reported to have de novo heterozygous truncating variants in HIST1H1E, which encodes linker histone H 1.4. However, their growth pattern appeared complex that four out of five patients had a decreasing height percentile over time, and three of these patients began with above-average heights but exhibited reductions to average heights or below when they were older. Herein, we report a female patient with intellectual disability and distinctive facial features including a wide nasal bridge and prominent cheek bones. She did not exhibit skeletal overgrowth, but she had a short stature at 21 years of age. An exome analysis identified a de novo heterozygous 1-bp duplication in HIST1H1E, that is, c.433dup p.(Ala145Glyfs*51). The physical features of the proposita were essentially the same as those observed in patients with the aforementioned HIST1H1E-related overgrowth syndrome. Our review of the growth trajectories in seven patients showed that five of seven patients did not exhibit skeletal overgrowth. This "lack of overgrowth in overgrowth syndrome" is reminiscent of a subset of patients with a short stature who have Sotos syndrome, a prototypic overgrowth syndrome. Considering this complexity in growth, this newly identified condition should be referred to as Rahman syndrome.
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http://dx.doi.org/10.1002/ajmg.a.38616DOI Listing
March 2018

Redefining the phenotypic spectrum of de novo heterozygous CDK13 variants: Three patients without cardiac defects.

Eur J Med Genet 2018 May 6;61(5):243-247. Epub 2017 Dec 6.

Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan. Electronic address:

Recently, 7 patients with de novo constitutional non-synonymous mutations in the CDK13 gene were ascertained through a trio exome analysis of a large cohort of 610 patients with congenital cardiac diseases. Despite another report describing 9 additional patients, the clinical spectrum of this condition has yet to be defined. Herein, we report 3 patients with heterozygous constitutional CDK13 mutations, who were ascertained through exome analysis of children with intellectual disability and minor anomalies, who lacked cardiac anomalies. Two patients had a c.2149G > A, p.Gly717Arg mutation, and one had a c.2525A > G, p. Asn842Ser mutation. A review of the previously described patients and those described herein has enabled the following points to be clarified. First, congenital heart diseases are not an essential feature (13/19). Second, nasal features may help syndromic recognition (14/16). Third, widely spaced and peg-shaped teeth may represent a previously unappreciated diagnostic clue for this newly identified syndrome. Here, we show that p.Gly717Arg represents a hotspot in addition to p.Asn842Ser. We suggest that this CDK13-related disorder may represent a clinically recognizable syndrome.
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http://dx.doi.org/10.1016/j.ejmg.2017.12.004DOI Listing
May 2018

Biallelic mutations in NALCN: Expanding the genotypic and phenotypic spectra of IHPRF1.

Am J Med Genet A 2018 02 23;176(2):431-437. Epub 2017 Nov 23.

Department of Pediatrics, Aichi Human Service Center, Central Hospital, Aichi, Japan.

Loss-of function mutations in NALCN on chromosome 13q, a sodium leak channel that maintains baseline neuronal excitability, cause infantile hypotonia with psychomotor retardation and characteristic faces 1 (IHPRF1, OMIM #615419). Here, we document two individuals with early onset hypotonia with poor feeding and intellectual disability who were compatible with a diagnosis of IHPRF1. The two patients had bi-allelic mutations in NALCN through two different genetic mechanisms: Patient 1 had bi-allelic splice site mutations, that is c.1267-2A>G, derived from heterozygous parents, while Patient 2 had a partial maternal uniparental isodisomy that harbored a frameshift mutation, that is c.2022_2023delAT, in chromosome 13 that was detected through a dedicated algorithm for homozygosity data mapping in whole exome sequencing. The delineation of the exact pattern of inheritance provided vital information regarding the risk of recurrence. In animal models with Nalcn mutations, two behavioral phenotypes, that are, postnatal dyspnea and sleep disturbance, have been reported. Our observations of the two patients with postnatal dyspnea and one patient with sleep disturbance support an association between these two behavioral phenotypes and NALCN mutations in humans. The routine use of a detection algorithm for homozygosity data mapping might improve the diagnostic yields of next-generation sequencing.
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http://dx.doi.org/10.1002/ajmg.a.38543DOI Listing
February 2018

Genomic Characterization of Chromosomal Insertions: Insights into the Mechanisms Underlying Chromothripsis.

Cytogenet Genome Res 2017 27;153(1):1-9. Epub 2017 Oct 27.

Division of Molecular Genetics, Institute for Comprehensive Medical Science (ICMS), and Genome and Transcriptome Analysis Center, Fujita Health University, Toyoake, Department of Pediatrics, Central Hospital, Aichi Human Service Center, Kasugai, Department of Pediatrics, Toyota Kosei Hospital, Toyota, Department of Obstetrics and Gynecology, Faculty of Medicine, Kagoshima University, and Takeuchi Ladies Clinic/Infertility Center, Kagoshima, and Education Center, Asahikawa Medical University, Hokkaido, Japan.

Chromosomal insertions are rare structural rearrangements, and the molecular mechanisms underlying their origin are unknown. In this study, we used whole genome sequencing to analyze breakpoints and junction sequences in 4 patients with chromosomal insertions. Our analysis revealed that none of the 4 cases involved a simple insertion mediated by a 3-chromosomal breakage and rejoining events. The inserted fragments consisted of multiple pieces derived from a localized genomic region, which were shuffled and rejoined in a disorderly fashion with variable copy number alterations. The junctions were blunt ended or with short microhomologies or short microinsertions, suggesting the involvement of nonhomologous end-joining. In one case, analysis of the parental origin of the chromosomes using nucleotide variations within the insertion revealed that maternal chromosomal segments were inserted into the paternal chromosome. This patient also carried both maternal alleles, suggesting the presence of zygotic trisomy. These data indicate that chromosomal shattering may occur in association with trisomy rescue in the early postzygotic stage.
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http://dx.doi.org/10.1159/000481586DOI Listing
January 2018

Comprehensive investigation of CASK mutations and other genetic etiologies in 41 patients with intellectual disability and microcephaly with pontine and cerebellar hypoplasia (MICPCH).

PLoS One 2017 7;12(8):e0181791. Epub 2017 Aug 7.

Department of Molecular Cytogenetics, Medical Research Institute and Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.

The CASK gene (Xp11.4) is highly expressed in the mammalian nervous system and plays several roles in neural development and synaptic function. Loss-of-function mutations of CASK are associated with intellectual disability and microcephaly with pontine and cerebellar hypoplasia (MICPCH), especially in females. Here, we present a comprehensive investigation of 41 MICPCH patients, analyzed by mutational search of CASK and screening of candidate genes using an SNP array, targeted resequencing and whole-exome sequencing (WES). In total, we identified causative or candidate genomic aberrations in 37 of the 41 cases (90.2%). CASK aberrations including a rare mosaic mutation in a male patient, were found in 32 cases, and a mutation in ITPR1, another known gene in which mutations are causative for MICPCH, was found in one case. We also found aberrations involving genes other than CASK, such as HDAC2, MARCKS, and possibly HS3ST5, which may be associated with MICPCH. Moreover, the targeted resequencing screening detected heterozygous variants in RELN in two cases, of uncertain pathogenicity, and WES analysis suggested that concurrent mutations of both DYNC1H1 and DCTN1 in one case could lead to MICPCH. Our results not only identified the etiology of MICPCH in nearly all the investigated patients but also suggest that MICPCH is a genetically heterogeneous condition, in which CASK inactivating mutations appear to account for the majority of cases.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0181791PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5546575PMC
September 2017

Haploinsufficiency of associated with cerebellar abnormalities in 2p15p16.1 deletion syndrome.

Mol Genet Genomic Med 2017 Jul 22;5(4):429-437. Epub 2017 May 22.

Division of Medical GeneticsKanagawa Children's Medical CenterYokohamaJapan.

Background: Chromosome 2p15p16.1 deletion syndrome is a rare genetic disorder characterized by intellectual disability (ID), neurodevelopmental delay, language delay, growth retardation, microcephaly, structural brain abnormalities, and dysmorphic features. More than 30 patients with 2p15p16.1 microdeletion syndrome have been reported in the literature.

Methods: Molecular analysis was performed using microarray-based comparative genomic hybridization (array CGH). Clinical characteristics and brain magnetic resonance imaging features of these patients were also reviewed.

Results: We identified four patients with ID, neurodevelopmental delay, brain malformations, and dysmorphic features; two patients with 2p15p16.1 deletions (3.24 Mb, 5.04 Mb), one patient with 2p16.1 deletion (1.12 Mb), and one patient with 2p14p16.1 deletion (5.12 Mb). Three patients with 2p15p16.1 deletions or 2p16.1 deletions encompassing ,, and showed hypoplasia of the pons and cerebellum. The patient with 2p14p16.1 deletion, which did not include three genes showed normal size and shape of the cerebellar hemispheres and pons.

Conclusion: The zinc finger transcription factor associated with the BAF chromatin remodeling complex has been identified to be critical for neural development and haploinsufficiency is closely related to cerebellar abnormalities.
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http://dx.doi.org/10.1002/mgg3.289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5511803PMC
July 2017

Temple syndrome: comprehensive molecular and clinical findings in 32 Japanese patients.

Genet Med 2017 12 31;19(12):1356-1366. Epub 2017 May 31.

Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.

PurposeTemple syndrome (TS14) is a rare imprinting disorder caused by aberrations at the 14q32.2 imprinted region. Here, we report comprehensive molecular and clinical findings in 32 Japanese patients with TS14.MethodsWe performed molecular studies for TS14 in 356 patients with variable phenotypes, and clinical studies in all TS14 patients, including 13 previously reported.ResultsWe identified 19 new patients with TS14, and the total of 32 patients was made up of 23 patients with maternal uniparental disomy (UPD(14)mat), six patients with epimutations, and three patients with microdeletions. Clinical studies revealed both Prader-Willi syndrome (PWS)-like marked hypotonia and Silver-Russell syndrome (SRS)-like phenotype in 50% of patients, PWS-like hypotonia alone in 20% of patients, SRS-like phenotype alone in 20% of patients, and nonsyndromic growth failure in the remaining 10% of patients in infancy, and gonadotropin-dependent precocious puberty in 76% of patients who were pubescent or older.ConclusionThese results suggest that TS14 is not only a genetically diagnosed entity but also a clinically recognizable disorder. Genetic testing for TS14 should be considered in patients with growth failure plus both PWS-like hypotonia and SRS-like phenotypes in infancy, and/or precocious puberty, as well as a familial history of Kagami-Ogata syndrome due to maternal microdeletion at 14q32.2.
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http://dx.doi.org/10.1038/gim.2017.53DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5729347PMC
December 2017