Publications by authors named "Naomi Meeks"

20 Publications

  • Page 1 of 1

Expanding the phenotype of ASXL3-related syndrome: A comprehensive description of 45 unpublished individuals with inherited and de novo pathogenic variants in ASXL3.

Am J Med Genet A 2021 Nov 26;185(11):3446-3458. Epub 2021 Aug 26.

Neurology Clinic, Department of Medicine, Santa Maria della Misericordia Hospital, University of Perugia, Perugia, Italy.

The study aimed at widening the clinical and genetic spectrum of ASXL3-related syndrome, a neurodevelopmental disorder, caused by truncating variants in the ASXL3 gene. In this international collaborative study, we have undertaken a detailed clinical and molecular analysis of 45 previously unpublished individuals with ASXL3-related syndrome, as well as a review of all previously published individuals. We have reviewed the rather limited functional characterization of pathogenic variants in ASXL3 and discuss current understanding of the consequences of the different ASXL3 variants. In this comprehensive analysis of ASXL3-related syndrome, we define its natural history and clinical evolution occurring with age. We report familial ASXL3 pathogenic variants, characterize the phenotype in mildly affected individuals and discuss nonpenetrance. We also discuss the role of missense variants in ASXL3. We delineate a variable but consistent phenotype. The most characteristic features are neurodevelopmental delay with consistently limited speech, significant neuro-behavioral issues, hypotonia, and feeding difficulties. Distinctive features include downslanting palpebral fissures, hypertelorism, tubular nose with a prominent nasal bridge, and low-hanging columella. The presented data will inform clinical management of individuals with ASXL3-related syndrome and improve interpretation of new ASXL3 sequence variants.
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http://dx.doi.org/10.1002/ajmg.a.62465DOI Listing
November 2021

A Novel Intronic Pathogenic Variant in With a Dominant Negative Mechanism Causes Attenuated Lipoid Congenital Adrenal Hyperplasia.

J Investig Med High Impact Case Rep 2021 Jan-Dec;9:23247096211014685

University of Colorado Anschutz Medical Campus, Aurora, CO, USA.

Lipoid congenital adrenal hyperplasia (LCAH) is typically inherited as an autosomal recessive condition. There are 3 reports of individuals with a dominantly acting heterozygous variant leading to a clinically significant phenotype. We report a 46,XY child with a novel heterozygous intronic variant in resulting in LCAH with an attenuated genital phenotype. The patient presented with neonatal hypoglycemia and had descended testes with a fused scrotum and small phallus. Evaluation revealed primary adrenal insufficiency with deficiencies of cortisol, aldosterone, and androgens. He was found to have a de novo heterozygous novel variant in : c.65-2A>C. We report a case of a novel variant and review of other dominant mutations at the same position in the literature. Clinicians should be aware of the possibility of attenuated genital phenotypes of LCAH and the contribution of de novo variants in at c.65-2 to the pathogenesis of that phenotype.
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http://dx.doi.org/10.1177/23247096211014685DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8114284PMC
October 2021

Genomic regions associated with microdeletion/microduplication syndromes exhibit extreme diversity of structural variation.

Genetics 2021 02;217(2)

Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, CO 80045, USA.

Segmental duplications (SDs) are a class of long, repetitive DNA elements whose paralogs share a high level of sequence similarity with each other. SDs mediate chromosomal rearrangements that lead to structural variation in the general population as well as genomic disorders associated with multiple congenital anomalies, including the 7q11.23 (Williams-Beuren Syndrome, WBS), 15q13.3, and 16p12.2 microdeletion syndromes. Population-level characterization of SDs has generally been lacking because most techniques used for analyzing these complex regions are both labor and cost intensive. In this study, we have used a high-throughput technique to genotype complex structural variation with a single molecule, long-range optical mapping approach. We characterized SDs and identified novel structural variants (SVs) at 7q11.23, 15q13.3, and 16p12.2 using optical mapping data from 154 phenotypically normal individuals from 26 populations comprising five super-populations. We detected several novel SVs for each locus, some of which had significantly different prevalence between populations. Additionally, we localized the microdeletion breakpoints to specific paralogous duplicons located within complex SDs in two patients with WBS, one patient with 15q13.3, and one patient with 16p12.2 microdeletion syndromes. The population-level data presented here highlights the extreme diversity of large and complex SVs within SD-containing regions. The approach we outline will greatly facilitate the investigation of the role of inter-SD structural variation as a driver of chromosomal rearrangements and genomic disorders.
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http://dx.doi.org/10.1093/genetics/iyaa038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8045732PMC
February 2021

Germline mutation in : a heterogeneous, multi-systemic developmental disorder characterized by transcriptional dysregulation.

HGG Adv 2021 Jan 20;2(1). Epub 2020 Nov 20.

Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.

germline variation in was recently reported to associate with a neurodevelopmental disorder. We report twelve individuals harboring putatively pathogenic or inherited variants in , detail their phenotypes, and map all known variants to the domain structure of and crystal structure of RNA polymerase II. Affected individuals were ascertained from a local data lake, pediatric genetics clinic, and an online community of families of affected individuals. These include six affected by missense variants (including one previously reported individual), four clinical laboratory samples affected by missense variation with unknown inheritance-with yeast functional assays further supporting altered function-one affected by a in-frame deletion, and one affected by a C-terminal frameshift variant inherited from a largely asymptomatic mother. Recurrently observed phenotypes include ataxia, joint hypermobility, short stature, skin abnormalities, congenital cardiac abnormalities, immune system abnormalities, hip dysplasia, and short Achilles tendons. We report a significantly higher occurrence of epilepsy (8/12, 66.7%) than previously reported (3/15, 20%) (p value = 0.014196; chi-square test) and a lower occurrence of hypotonia (8/12, 66.7%) than previously reported (14/15, 93.3%) (p value = 0.076309). -related developmental disorders likely represent a spectrum of related, multi-systemic developmental disorders, driven by distinct mechanisms, converging at a single locus.
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http://dx.doi.org/10.1016/j.xhgg.2020.100014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7928427PMC
January 2021

Defining the genotypic and phenotypic spectrum of X-linked MSL3-related disorder.

Genet Med 2021 02 11;23(2):384-395. Epub 2020 Nov 11.

Department of Pediatrics, Section of Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.

Purpose: We sought to delineate the genotypic and phenotypic spectrum of female and male individuals with X-linked, MSL3-related disorder (Basilicata-Akhtar syndrome).

Methods: Twenty-five individuals (15 males, 10 females) with causative variants in MSL3 were ascertained through exome or genome sequencing at ten different sequencing centers.

Results: We identified multiple variant types in MSL3 (ten nonsense, six frameshift, four splice site, three missense, one in-frame-deletion, one multi-exon deletion), most proven to be de novo, and clustering in the terminal eight exons suggesting that truncating variants in the first five exons might be compensated by an alternative MSL3 transcript. Three-dimensional modeling of missense and splice variants indicated that these have a deleterious effect. The main clinical findings comprised developmental delay and intellectual disability ranging from mild to severe. Autism spectrum disorder, muscle tone abnormalities, and macrocephaly were common as well as hearing impairment and gastrointestinal problems. Hypoplasia of the cerebellar vermis emerged as a consistent magnetic resonance image (MRI) finding. Females and males were equally affected. Using facial analysis technology, a recognizable facial gestalt was determined.

Conclusion: Our aggregated data illustrate the genotypic and phenotypic spectrum of X-linked, MSL3-related disorder (Basilicata-Akhtar syndrome). Our cohort improves the understanding of disease related morbidity and allows us to propose detailed surveillance guidelines for affected individuals.
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http://dx.doi.org/10.1038/s41436-020-00993-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7862064PMC
February 2021

Predominant and novel de novo variants in 29 individuals with ALG13 deficiency: Clinical description, biomarker status, biochemical analysis, and treatment suggestions.

J Inherit Metab Dis 2020 11 5;43(6):1333-1348. Epub 2020 Aug 5.

Inova Translational Medicine Institute Division of Medical Genomics Inova Fairfax Hospital Falls Church, Virginia, USA.

Asparagine-linked glycosylation 13 homolog (ALG13) encodes a nonredundant, highly conserved, X-linked uridine diphosphate (UDP)-N-acetylglucosaminyltransferase required for the synthesis of lipid linked oligosaccharide precursor and proper N-linked glycosylation. De novo variants in ALG13 underlie a form of early infantile epileptic encephalopathy known as EIEE36, but given its essential role in glycosylation, it is also considered a congenital disorder of glycosylation (CDG), ALG13-CDG. Twenty-four previously reported ALG13-CDG cases had de novo variants, but surprisingly, unlike most forms of CDG, ALG13-CDG did not show the anticipated glycosylation defects, typically detected by altered transferrin glycosylation. Structural homology modeling of two recurrent de novo variants, p.A81T and p.N107S, suggests both are likely to impact the function of ALG13. Using a corresponding ALG13-deficient yeast strain, we show that expressing yeast ALG13 with either of the highly conserved hotspot variants rescues the observed growth defect, but not its glycosylation abnormality. We present molecular and clinical data on 29 previously unreported individuals with de novo variants in ALG13. This more than doubles the number of known cases. A key finding is that a vast majority of the individuals presents with West syndrome, a feature shared with other CDG types. Among these, the initial epileptic spasms best responded to adrenocorticotropic hormone or prednisolone, while clobazam and felbamate showed promise for continued epilepsy treatment. A ketogenic diet seems to play an important role in the treatment of these individuals.
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http://dx.doi.org/10.1002/jimd.12290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7722193PMC
November 2020

Mapping the Relationship between Dysmorphology and Cognitive, Behavioral, and Developmental Outcomes in Children with Autism Spectrum Disorder.

Autism Res 2020 07 22;13(7):1227-1238. Epub 2020 Jun 22.

National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.

Previous studies investigating the association between dysmorphology and cognitive, behavioral, and developmental outcomes among individuals with autism spectrum disorder (ASD) have been limited by the binary classification of dysmorphology and lack of comparison groups. We assessed the association using a continuous measure of dysmorphology severity (DS) in preschool children aged 2-5 years (322 with ASD and intellectual disability [ID], 188 with ASD without ID, and 371 without ASD from the general population [POP]). In bivariate analyses, an inverse association between DS and expressive language, receptive language, fine motor, and visual reception skills was observed in children with ASD and ID. An inverse association of DS with fine motor and visual reception skills, but not expressive language and receptive language, was found in children with ASD without ID. No associations were observed in POP children. These results persisted after exclusion of children with known genetic syndromes or major morphologic anomalies. Quantile regression models showed that the inverse relationships remained significant after adjustment for sex, race/ethnicity, maternal education, family income, study site, and preterm birth. DS was not associated with autistic traits or autism symptom severity, behaviors, or regression among children with ASD with or without ID. Thus, DS was associated with a global impairment of cognitive functioning in children with ASD and ID, but only with fine motor and visual reception deficits in children with ASD without ID. A better understanding is needed for mechanisms that explain the association between DS and cognitive impairment in children with different disorders. Autism Res 2020, 13: 1227-1238. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We examined whether having more dysmorphic features (DFs) was related to developmental problems among children with autism spectrum disorder (ASD) with or without intellectual disability (ID), and children without ASD from the general population (POP). Children with ASD and ID had more language, movement, and learning issues as the number of DFs increased. Children with ASD without ID had more movement and learning issues as the number of DFs increased. These relationships were not observed in the POP group. Implications are discussed.
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http://dx.doi.org/10.1002/aur.2314DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7424904PMC
July 2020

Automated syndrome diagnosis by three-dimensional facial imaging.

Genet Med 2020 10 1;22(10):1682-1693. Epub 2020 Jun 1.

Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA.

Purpose: Deep phenotyping is an emerging trend in precision medicine for genetic disease. The shape of the face is affected in 30-40% of known genetic syndromes. Here, we determine whether syndromes can be diagnosed from 3D images of human faces.

Methods: We analyzed variation in three-dimensional (3D) facial images of 7057 subjects: 3327 with 396 different syndromes, 727 of their relatives, and 3003 unrelated, unaffected subjects. We developed and tested machine learning and parametric approaches to automated syndrome diagnosis using 3D facial images.

Results: Unrelated, unaffected subjects were correctly classified with 96% accuracy. Considering both syndromic and unrelated, unaffected subjects together, balanced accuracy was 73% and mean sensitivity 49%. Excluding unrelated, unaffected subjects substantially improved both balanced accuracy (78.1%) and sensitivity (56.9%) of syndrome diagnosis. The best predictors of classification accuracy were phenotypic severity and facial distinctiveness of syndromes. Surprisingly, unaffected relatives of syndromic subjects were frequently classified as syndromic, often to the syndrome of their affected relative.

Conclusion: Deep phenotyping by quantitative 3D facial imaging has considerable potential to facilitate syndrome diagnosis. Furthermore, 3D facial imaging of "unaffected" relatives may identify unrecognized cases or may reveal novel examples of semidominant inheritance.
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http://dx.doi.org/10.1038/s41436-020-0845-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7521994PMC
October 2020

A clinically validated whole genome pipeline for structural variant detection and analysis.

BMC Genomics 2019 Jul 16;20(Suppl 8):545. Epub 2019 Jul 16.

Variantyx Inc, Framingham, MA, 01867, USA.

Background: With the continuing decrease in cost of whole genome sequencing (WGS), we have already approached the point of inflection where WGS testing has become economically feasible, facilitating broader access to the benefits that are helping to define WGS as the new diagnostic standard. WGS provides unique opportunities for detection of structural variants; however, such analyses, despite being recognized by the research community, have not previously made their way into routine clinical practice.

Results: We have developed a clinically validated pipeline for highly specific and sensitive detection of structural variants basing on 30X PCR-free WGS. Using a combination of breakpoint analysis of split and discordant reads, and read depth analysis, the pipeline identifies structural variants down to single base pair resolution. False positives are minimized using calculations for loss of heterozygosity and bi-modal heterozygous variant allele frequencies to enhance heterozygous deletion and duplication detection respectively. Compound and potential compound combinations of structural variants and small sequence changes are automatically detected. To facilitate clinical interpretation, identified variants are annotated with phenotype information derived from HGMD Professional and population allele frequencies derived from public and Variantyx allele frequency databases. Single base pair resolution enables easy visual inspection of potentially causal variants using the IGV genome browser as well as easy biochemical validation via PCR. Analytical and clinical sensitivity and specificity of the pipeline has been validated using analysis of Genome in a Bottle reference genomes and known positive samples confirmed by orthogonal sequencing technologies.

Conclusion: Consistent read depth of PCR-free WGS enables reliable detection of structural variants of any size. Annotation both on gene and variant level allows clinicians to match reported patient phenotype with detected variants and confidently report causative finding in all clinical cases used for validation.
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http://dx.doi.org/10.1186/s12864-019-5866-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6631445PMC
July 2019

A Novel Approach to Dysmorphology to Enhance the Phenotypic Classification of Autism Spectrum Disorder in the Study to Explore Early Development.

J Autism Dev Disord 2019 May;49(5):2184-2202

National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, 4770 Buford Hwy NE, Mailstop E-87, Atlanta, GA, 30341, USA.

The presence of multiple dysmorphic features in some children with autism spectrum disorder (ASD) might identify distinct ASD phenotypes and serve as potential markers for understanding causes and prognoses. To evaluate dysmorphology in ASD, children aged 3-6 years with ASD and non-ASD population controls (POP) from the Study to Explore Early Development were evaluated using a novel, systematic dysmorphology review approach. Separate analyses were conducted for non-Hispanic White, non-Hispanic Black, and Hispanic children. In each racial/ethnic group, ~ 17% of ASD cases were Dysmorphic compared with ~ 5% of POP controls. The ASD-POP differential was not explained by known genetic disorders or birth defects. In future epidemiologic studies, subgrouping ASD cases as Dysmorphic vs. Non-dysmorphic might help delineate risk factors for ASD.
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http://dx.doi.org/10.1007/s10803-019-03899-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6486433PMC
May 2019

The genotypic spectrum of ALDH7A1 mutations resulting in pyridoxine dependent epilepsy: A common epileptic encephalopathy.

J Inherit Metab Dis 2019 03 22;42(2):353-361. Epub 2019 Feb 22.

Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA.

Pyridoxine dependent epilepsy (PDE) is a treatable epileptic encephalopathy characterized by a positive response to pharmacologic doses of pyridoxine. Despite seizure control, at least 75% of individuals have intellectual disability and developmental delay. Current treatment paradigms have resulted in improved cognitive outcomes emphasizing the importance of an early diagnosis. As genetic testing is increasingly accepted as first tier testing for epileptic encephalopathies, we aimed to provide a comprehensive overview of ALDH7A1 mutations that cause PDE. The genotypes, ethnic origin and reported gender was collected from 185 subjects with a diagnosis of PDE. The population frequency for the variants in this report and the existing literature were reviewed in the Genome Aggregation Database (gnomAD). Novel variants identified in population databases were also evaluated through in silico prediction software and select variants were over-expressed in an E.coli-based expression system to measure α-aminoadipic semialdehyde dehydrogenase activity and production of α-aminoadipic acid. This study adds 47 novel variants to the literature resulting in a total of 165 reported pathogenic variants. Based on this report, in silico predictions, and general population data, we estimate an incidence of approximately 1:64,352 live births. This report provides a comprehensive overview of known ALDH7A1 mutations that cause PDE, and suggests that PDE may be more common than initially estimated. Due to the relative high frequency of the disease, the likelihood of under-diagnosis given the wide clinical spectrum and limited awareness among clinicians as well as the cognitive improvement noted with early treatment, newborn screening for PDE may be warranted.
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http://dx.doi.org/10.1002/jimd.12045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6345606PMC
March 2019

Functional Dysregulation of CDC42 Causes Diverse Developmental Phenotypes.

Am J Hum Genet 2018 02 25;102(2):309-320. Epub 2018 Jan 25.

GeneDX, Gaithersburg, MD 20877, USA.

Exome sequencing has markedly enhanced the discovery of genes implicated in Mendelian disorders, particularly for individuals in whom a known clinical entity could not be assigned. This has led to the recognition that phenotypic heterogeneity resulting from allelic mutations occurs more commonly than previously appreciated. Here, we report that missense variants in CDC42, a gene encoding a small GTPase functioning as an intracellular signaling node, underlie a clinically heterogeneous group of phenotypes characterized by variable growth dysregulation, facial dysmorphism, and neurodevelopmental, immunological, and hematological anomalies, including a phenotype resembling Noonan syndrome, a developmental disorder caused by dysregulated RAS signaling. In silico, in vitro, and in vivo analyses demonstrate that mutations variably perturb CDC42 function by altering the switch between the active and inactive states of the GTPase and/or affecting CDC42 interaction with effectors, and differentially disturb cellular and developmental processes. These findings reveal the remarkably variable impact that dominantly acting CDC42 mutations have on cell function and development, creating challenges in syndrome definition, and exemplify the importance of functional profiling for syndrome recognition and delineation.
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http://dx.doi.org/10.1016/j.ajhg.2017.12.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985417PMC
February 2018

De Novo Missense Mutations in DHX30 Impair Global Translation and Cause a Neurodevelopmental Disorder.

Am J Hum Genet 2017 Nov;101(5):716-724

Department of Pediatric Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.

DHX30 is a member of the family of DExH-box helicases, which use ATP hydrolysis to unwind RNA secondary structures. Here we identified six different de novo missense mutations in DHX30 in twelve unrelated individuals affected by global developmental delay (GDD), intellectual disability (ID), severe speech impairment and gait abnormalities. While four mutations are recurrent, two are unique with one affecting the codon of one recurrent mutation. All amino acid changes are located within highly conserved helicase motifs and were found to either impair ATPase activity or RNA recognition in different in vitro assays. Moreover, protein variants exhibit an increased propensity to trigger stress granule (SG) formation resulting in global translation inhibition. Thus, our findings highlight the prominent role of translation control in development and function of the central nervous system and also provide molecular insight into how DHX30 dysfunction might cause a neurodevelopmental disorder.
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http://dx.doi.org/10.1016/j.ajhg.2017.09.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673606PMC
November 2017

Lipogranulomatous subconjunctival nodules: a novel presentation in Blau syndrome.

J AAPOS 2017 Jun 19;21(3):249-251. Epub 2017 May 19.

Department of Ophthalmology, University of Colorado, Aurora.

Blau syndrome is an early-onset granulomatous disease known to affect the skin, joints, and eyes. We report a child with diffuse rash, arthritis, and subconjunctival nodules. Biopsy of the bulbar conjunctiva revealed noncaseating lipogranulomas that lead to a diagnosis of Blau syndrome. To our knowledge, noncaseating lipogranulomas of the conjunctiva have not been reported previously as a presenting finding in Blau syndrome. Although uveitis is the classic manifestation, it is important to broaden the awareness of other ocular signs, as these variations can aid in diagnosis.
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http://dx.doi.org/10.1016/j.jaapos.2017.05.011DOI Listing
June 2017

Juvenile myelomonocytic leukemia-associated variants are associated with neo-natal lethal Noonan syndrome.

Eur J Hum Genet 2017 04 18;25(4):509-511. Epub 2017 Jan 18.

Laboratory for Molecular Medicine, Partners Personalized Medicine, Cambridge, MA, USA.

Gain-of-function variants in some RAS-MAPK pathway genes, including PTPN11 and NRAS, are associated with RASopathies and/or acquired hematological malignancies, most notably juvenile myelomonocytic leukemia (JMML). With rare exceptions, the spectrum of germline variants causing RASopathies does not overlap with the somatic variants identified in isolated JMML. Studies comparing these variants suggest a stronger gain-of-function activity in the JMML variants. As JMML variants have not been identified as germline defects and have a greater impact on protein function, it has been speculated that they would be embryonic lethal. Here we identified three variants, which have previously only been identified in isolated somatic JMML and other sporadic cancers, in four cases with a severe pre- or neo-natal lethal presentation of Noonan syndrome. These cases support the hypothesis that these stronger gain-of-function variants are rarely compatible with life.
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http://dx.doi.org/10.1038/ejhg.2016.202DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5386422PMC
April 2017

A 2.78-Mb duplication on chromosome 21q22.11 implicates candidate genes in the partial trisomy 21 phenotype.

NPJ Genom Med 2016 2;1. Epub 2016 Mar 2.

Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Down syndrome (DS) is the most common genetic cause of intellectual disability (ID) and in the majority of cases is the result of complete trisomy 21. The hypothesis that the characteristic DS clinical features are due to a single DS critical region (DSCR) at distal chromosome 21q has been refuted by recently reported segmental trisomy 21 cases characterised by microarray-based comparative genomic hybridisation (aCGH). These rare cases have implicated multiple regions on chromosome 21 in the aetiology of distinct features of DS; however, the map of chromosome 21 copy-number aberrations and their associated phenotypes remains incompletely defined. We report a child with ID who was deemed very high risk for DS on antenatal screening (1 in 13) and has partial, but distinct, dysmorphologic features of DS without congenital heart disease (CHD). Oligonucleotide aCGH testing of the proband detected a previously unreported 2.78-Mb duplication on chromosome 21q22.11 that includes 16 genes; however, this aberration does not harbour any of the historical DSCR genes (, , and ). This informative case implicates previously under-recognised candidate genes (, and ) in the pathogenesis of specific DS clinical features and supports a critical region for CHD located more distal on chromosome 21q. In addition, this unique case illustrates how the increasing resolution of microarray and high-throughput sequencing technologies can continue to reveal new biology and enhance understanding of widely studied genetic diseases that were originally described over 50 years ago.
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http://dx.doi.org/10.1038/npjgenmed.2016.3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102301PMC
March 2016

The phenotypic spectrum of Schaaf-Yang syndrome: 18 new affected individuals from 14 families.

Genet Med 2017 01 19;19(1):45-52. Epub 2016 May 19.

Department of Molecular Neuroscience, University College London Institute of Neurology, London, UK.

Purpose: Truncating mutations in the maternally imprinted, paternally expressed gene MAGEL2, which is located in the Prader-Willi critical region 15q11-13, have recently been reported to cause Schaaf-Yang syndrome, a Prader-Willi-like disease that manifests as developmental delay/intellectual disability, hypotonia, feeding difficulties, and autism spectrum disorder. The causality of the reported variants in the context of the patients' phenotypes was questioned, as MAGEL2 whole-gene deletions seem to cause little or no clinical phenotype.

Methods: Here we report a total of 18 newly identified individuals with Schaaf-Yang syndrome from 14 families, including 1 family with 3 individuals found to be affected with a truncating variant of MAGEL2, 11 individuals who are clinically affected but were not tested molecularly, and a presymptomatic fetal sibling carrying the pathogenic MAGEL2 variant.

Results: All cases harbor truncating mutations of MAGEL2, and nucleotides c.1990-1996 arise as a mutational hotspot, with 10 individuals and 1 fetus harboring a c.1996dupC (p.Q666fs) mutation and 2 fetuses harboring a c.1996delC (p.Q666fs) mutation. The phenotypic spectrum of Schaaf-Yang syndrome ranges from fetal akinesia to neurobehavioral disease and contractures of the small finger joints.

Conclusion: This study provides strong evidence for the pathogenicity of truncating mutations of the paternal allele of MAGEL2, refines the associated clinical phenotypes, and highlights implications for genetic counseling for affected families.Genet Med 19 1, 45-52.
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http://dx.doi.org/10.1038/gim.2016.53DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5116288PMC
January 2017

Genetic causes of pituitary hormone deficiencies.

Discov Med 2015 Mar;19(104):175-83

Section of Genetics, Department of Pediatrics, University of Colorado Denver and Children's Hospital Colorado, Aurora, CO 80045, USA.

In recent decades, dozens of genes that cause isolated and combined pituitary hormone deficiencies have been discovered. We will review the clinically relevant genes known to cause isolated and combined pituitary hormone deficiencies in humans. This review will address genetic causes of adrenocorticotropic hormone deficiency, thyroid stimulating hormone deficiency, growth hormone deficiency, hypogonadotropic hypogonadism, and diabetes insipidus. Additionally, we will discuss genetic causes of combined pituitary hormone deficiency, septo-optic dysplasia, holoprosencephaly, and multisystemic syndromes in which hypopituitarism is a significant component. With the widespread clinical availability of next generation sequencing and ongoing identification of new disease causing genes, genetic diagnoses are determined for increasing numbers of patients. With new insights into mechanisms of disease resulting from multiple gene interactions, an increasingly nuanced understanding of the underlying genetic etiology of pituitary hormone deficiencies is possible.
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March 2015
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