Publications by authors named "Karen Temple"

105 Publications

Successful pregnancies in an adult with Meier-Gorlin syndrome harboring biallelic CDT1 variants.

Am J Med Genet A 2021 03 18;185(3):871-876. Epub 2020 Dec 18.

Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.

Meier-Gorlin syndrome is an autosomal recessively inherited disorder of growth retardation, accompanied by microtia and patellae a/hypoplasia and characteristic facies. Pathogenic variants in genes associated with the initiation of DNA replication underlie the condition, with biallelic variants in CDT1 the most common cause. Using 10× Chromium genome sequencing, we report CDT1 variants in an adult female, with an inframe amino acid deletion inherited in trans with a deep intronic variant which likely serves as the branchpoint site in Intron 8. Splicing defects arising from this variant were confirmed through in vitro analysis. At 49 years, she represents the oldest patient with a molecular diagnosis described in the literature and is the first reported patient with Meier-Gorlin syndrome to have carried a successful pregnancy to term. Both of her pregnancies were complicated by postpartum hemorrhage and upon subsequent necessary hysterectomy, revealed uterine abnormalities. There is scant knowledge on reproductive ability and success in patients with Meier-Gorlin syndrome. Successful pregnancies among other clinically recognizable forms of primordial dwarfism have also not been described previously. This case is therefore of clinical interest for many forms of inherited growth retardation, and will assist in providing more information and clinical guidance for females of reproductive age.
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http://dx.doi.org/10.1002/ajmg.a.62016DOI Listing
March 2021

DNA Methylation Signature for EZH2 Functionally Classifies Sequence Variants in Three PRC2 Complex Genes.

Am J Hum Genet 2020 05 2;106(5):596-610. Epub 2020 Apr 2.

Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Pediatrics, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada. Electronic address:

Weaver syndrome (WS), an overgrowth/intellectual disability syndrome (OGID), is caused by pathogenic variants in the histone methyltransferase EZH2, which encodes a core component of the Polycomb repressive complex-2 (PRC2). Using genome-wide DNA methylation (DNAm) data for 187 individuals with OGID and 969 control subjects, we show that pathogenic variants in EZH2 generate a highly specific and sensitive DNAm signature reflecting the phenotype of WS. This signature can be used to distinguish loss-of-function from gain-of-function missense variants and to detect somatic mosaicism. We also show that the signature can accurately classify sequence variants in EED and SUZ12, which encode two other core components of PRC2, and predict the presence of pathogenic variants in undiagnosed individuals with OGID. The discovery of a functionally relevant signature with utility for diagnostic classification of sequence variants in EZH2, EED, and SUZ12 supports the emerging paradigm shift for implementation of DNAm signatures into diagnostics and translational research.
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http://dx.doi.org/10.1016/j.ajhg.2020.03.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7212265PMC
May 2020

Phenotype of genetically confirmed Silver-Russell syndrome beyond childhood.

J Med Genet 2020 10 13;57(10):683-691. Epub 2020 Feb 13.

Human Development and Health, Faculty of Medicine University of Southampton, Southampton, UK

Background: Silver-Russell syndrome is an imprinting disorder that restricts growth, resulting in short adult stature that may be ameliorated by treatment. Approximately 50% of patients have loss of methylation of the imprinting control region (H19/IGF2:IG-DMR) on 11p15.5 and 5%-10% have maternal uniparental disomy of chromosome 7. Most published research focuses on the childhood phenotype. Our aim was to describe the phenotypic characteristics of older patients with SRS.

Methods: A retrospective cohort of 33 individuals with a confirmed molecular diagnosis of SRS aged 13 years or above were carefully phenotyped.

Results: The median age of the cohort was 29.6 years; 60.6% had a height SD score (SDS) ≤-2 SDS despite 70% having received growth hormone treatment. Relative macrocephaly, feeding difficulties and a facial appearance typical of children with SRS were no longer discriminatory diagnostic features. In those aged ≥18 years, impaired glucose tolerance in 25%, hypertension in 33% and hypercholesterolaemia in 52% were noted. While 9/33 accessed special education support, university degrees were completed in 40.0% (>21 years). There was no significant correlation between quality of life and height SDS. 9/25 were parents and none of the 17 offsprings had SRS.

Conclusion: Historical treatment regimens for SRS were not sufficient for normal adult growth and further research to optimise treatment is justified. Clinical childhood diagnostic scoring systems are not applicable to patients presenting in adulthood and SRS diagnosis requires molecular confirmation. Metabolic ill-health warrants further investigation but SRS is compatible with a normal quality of life including normal fertility in many cases.
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http://dx.doi.org/10.1136/jmedgenet-2019-106561DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7525777PMC
October 2020

HIST1H1E heterozygous protein-truncating variants cause a recognizable syndrome with intellectual disability and distinctive facial gestalt: A study to clarify the HIST1H1E syndrome phenotype in 30 individuals.

Am J Med Genet A 2019 10 9;179(10):2049-2055. Epub 2019 Aug 9.

Institute of Cancer Research, London, UK.

Histone Gene Cluster 1 Member E, HIST1H1E, encodes Histone H1.4, is one of a family of epigenetic regulator genes, acts as a linker histone protein, and is responsible for higher order chromatin structure. HIST1H1E syndrome (also known as Rahman syndrome, OMIM #617537) is a recently described intellectual disability (ID) syndrome. Since the initial description of five unrelated individuals with three different heterozygous protein-truncating variants (PTVs) in the HIST1H1E gene in 2017, we have recruited 30 patients, all with HIST1H1E PTVs that result in the same shift in frame and that cluster to a 94-base pair region in the HIST1H1E carboxy terminal domain. The identification of 30 patients with HIST1H1E variants has allowed the clarification of the HIST1H1E syndrome phenotype. Major findings include an ID and a recognizable facial appearance. ID was reported in all patients and is most frequently of moderate severity. The facial gestalt consists of a high frontal hairline and full lower cheeks in early childhood and, in later childhood and adulthood, affected individuals have a strikingly high frontal hairline, frontal bossing, and deep-set eyes. Other associated clinical features include hypothyroidism, abnormal dentition, behavioral issues, cryptorchidism, skeletal anomalies, and cardiac anomalies. Brain magnetic resonance imaging (MRI) is frequently abnormal with a slender corpus callosum a frequent finding.
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http://dx.doi.org/10.1002/ajmg.a.61321DOI Listing
October 2019

Growth disrupting mutations in epigenetic regulatory molecules are associated with abnormalities of epigenetic aging.

Genome Res 2019 07 3;29(7):1057-1066. Epub 2019 Jun 3.

Institute of Biomedical and Clinical Science, University of Exeter Medical School, RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Exeter, EX2 5DW, United Kingdom.

Germline mutations in fundamental epigenetic regulatory molecules including DNA methyltransferase 3 alpha () are commonly associated with growth disorders, whereas somatic mutations are often associated with malignancy. We profiled genome-wide DNA methylation patterns in c.2312G > A; p.(Arg771Gln) carriers in a large Amish sibship with Tatton-Brown-Rahman syndrome (TBRS), their mosaic father, and 15 TBRS patients with distinct pathogenic de novo variants. This defined widespread DNA hypomethylation at specific genomic sites enriched at locations annotated as genes involved in morphogenesis, development, differentiation, and malignancy predisposition pathways. TBRS patients also displayed highly accelerated DNA methylation aging. These findings were most marked in a carrier of the AML-associated driver mutation p.Arg882Cys. Our studies additionally defined phenotype-related accelerated and decelerated epigenetic aging in two histone methyltransferase disorders: Sotos syndrome overgrowth disorder and Kabuki syndrome growth impairment. Together, our findings provide fundamental new insights into aberrant epigenetic mechanisms, the role of epigenetic machinery maintenance, and determinants of biological aging in these growth disorders.
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http://dx.doi.org/10.1101/gr.243584.118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6633263PMC
July 2019

A Diagnosis for All Rare Genetic Diseases: The Horizon and the Next Frontiers.

Cell 2019 03;177(1):32-37

Faculty of Health and Medical Sciences, University of Western Australia Medical School, Perth, WA, Australia; Western Australian Register of Developmental Anomalies, Genetic Services of Western Australia, Perth, WA, Australia; Office of Population Health Genomics, Western Australian Department of Health, Perth, WA, Australia.

The introduction of exome sequencing in the clinic has sparked tremendous optimism for the future of rare disease diagnosis, and there is exciting opportunity to further leverage these advances. To provide diagnostic clarity to all of these patients, however, there is a critical need for the field to develop and implement strategies to understand the mechanisms underlying all rare diseases and translate these to clinical care.
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http://dx.doi.org/10.1016/j.cell.2019.02.040DOI Listing
March 2019

Growth Hormone Improves Short-Term Growth in Patients with Temple Syndrome.

Horm Res Paediatr 2018 5;90(6):407-413. Epub 2019 Mar 5.

Cincinnati Center for Growth Disorders, Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.

Background/aims: Temple syndrome is an imprinting disorder caused by maternal uniparental disomy of chromosome 14 (mat UPD14), paternal deletion of 14q32 or paternal hypomethylation of the intergenic differentially methylated region (MEG3/DLK1 IG-DMR). Patients with Temple syndrome have pre- and postnatal growth restriction, short stature, hypotonia, small hands and feet and precocious puberty. We sought to determine whether treatment with growth hormone improves growth outcomes in patients with Temple syndrome.

Methods: This was a retrospective observational study reviewing the medical records of 14 patients with Temple syndrome, 7 of whom were treated with growth hormone.

Results: After 1 year of growth hormone treatment, the height standard deviation score (SDS) increased a median of 1.31 SDS with a median increased height velocity of 5.30 cm/year.

Conclusions: These results suggest short-term improvement in height SDS with growth hormone treatment similar to the response in patients treated under the small for gestational age indication. We recommend considering growth hormone therapy in all patients with Temple syndrome who have short stature.
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http://dx.doi.org/10.1159/000496700DOI Listing
August 2019

Discrepant molecular and clinical diagnoses in Beckwith-Wiedemann and Silver-Russell syndromes.

Genet Res (Camb) 2019 03 4;101:e3. Epub 2019 Mar 4.

Institute of Human Genetics, University Hospital, Technical University of Aachen,Aachen,Germany.

Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) are two imprinting disorders associated with opposite molecular alterations in the 11p15.5 imprinting centres. Their clinical diagnosis is confirmed by molecular testing in 50-70% of patients. The authors from different reference centres for BWS and SRS have identified single patients with unexpected and even contradictory molecular findings in respect to the clinical diagnosis. These patients clinically do not fit the characteristic phenotypes of SRS or BWS, but illustrate their clinical heterogeneity. Thus, comprehensive molecular testing is essential for accurate diagnosis and appropriate management, to avoid premature clinical diagnosis and anxiety for the families.
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http://dx.doi.org/10.1017/S001667231900003XDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7044970PMC
March 2019

Pathogenicity and selective constraint on variation near splice sites.

Genome Res 2019 02 26;29(2):159-170. Epub 2018 Dec 26.

Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, United Kingdom.

Mutations that perturb normal pre-mRNA splicing are significant contributors to human disease. We used exome sequencing data from 7833 probands with developmental disorders (DDs) and their unaffected parents, as well as more than 60,000 aggregated exomes from the Exome Aggregation Consortium, to investigate selection around the splice sites and quantify the contribution of splicing mutations to DDs. Patterns of purifying selection, a deficit of variants in highly constrained genes in healthy subjects, and excess de novo mutations in patients highlighted particular positions within and around the consensus splice site of greater functional relevance. By using mutational burden analyses in this large cohort of proband-parent trios, we could estimate in an unbiased manner the relative contributions of mutations at canonical dinucleotides (73%) and flanking noncanonical positions (27%), and calculate the positive predictive value of pathogenicity for different classes of mutations. We identified 18 patients with likely diagnostic de novo mutations in dominant DD-associated genes at noncanonical positions in splice sites. We estimate 35%-40% of pathogenic variants in noncanonical splice site positions are missing from public databases.
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http://dx.doi.org/10.1101/gr.238444.118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6360807PMC
February 2019

Genetics, molar pregnancies and medieval ideas of monstrous births: the lump of flesh in .

Med Humanit 2019 Mar 7;45(1):2-9. Epub 2018 Aug 7.

Department of Human Genetics and Genomics Medicine, Faculty of Medicine, University of Southampton, Southampton, UK.

The medieval English romance gives an account of a birth of a lump of flesh. This has been considered as fantastic and monstrous in past literature, the horrific union of a Christian and Saracen. However, while the text certainly speaks to miscegenation, we propose that this lump of flesh is actually a hydatidiform mole. We trace the hydatidiform mole from antiquity, surrounding it with contextual medieval examples, from theology, history and medicine, that also describe abnormal births as 'lumps of flesh'. By discussing medieval ideas of monsters as a warning sign, we interpret the lump of flesh in terms of abnormal births, seed transmission, parental contribution and sin. Ideas of warning, blame and intervention present themselves as a response to moles both in medieval texts as well as in modern reactions to hydatidiform moles. We explore the epigenetics of hydatidiform moles and relate them to the medieval text. In , the fault for the lump of flesh could reside with either parent; we find that this is also the case in the genetic formation of the hydatidiform mole; we also argue that the epigenetics supports medieval theories of seed transmission.
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http://dx.doi.org/10.1136/medhum-2017-011387DOI Listing
March 2019

Lived experience of Silver-Russell syndrome: implications for management during childhood and into adulthood.

Arch Dis Child 2019 01 28;104(1):76-82. Epub 2018 Jun 28.

Faculty of Medicine, Clinical Ethics and Law, University of Southampton, Southampton, UK.

Objective: There is limited information on the psychosocial impact of growing up with Silver-Russell syndrome (SRS), characterised by slow growth in utero leading to short stature in adulthood. Such information could aid families in making difficult treatment decisions and guide management strategies for health professionals. We aimed to explore the lived experience of people with SRS across the lifespan.

Design/setting/patients: In-depth, semi-structured interviews were conducted between January 2015 and October 2016 with a sample of 15 adults (six women) with genetically confirmed SRS from the UK. Qualitative interviews were transcribed and coded to identify similarities and differences: codes were then grouped to form overarching themes.

Results: Four themes were identified from participant accounts: (1) appearance-related concerns extending beyond height; (2) strategies to deal with real and perceived threats; (3) women's experiences of pain, disability and feeling older than their years; and (4) feeling overlooked in romantic relationships. These themes show that other factors, beyond short stature, affect patient well-being and indicate a mismatch between patient need and healthcare provision.

Conclusions: Challenges in SRS during childhood and adolescence were central to the psychosocial impact of SRS, and were not limited to height. These challenges, as well as symptoms such as pain and fatigue for women, have not previously been documented. To help individuals with SRS develop strategies to manage psychosocial issues, we recommend clinicians incorporate psychological services as an integral part of multidisciplinary teams managing individuals with SRS during childhood, adolescence and adulthood.
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http://dx.doi.org/10.1136/archdischild-2018-314952DOI Listing
January 2019

The Tatton-Brown-Rahman Syndrome: A clinical study of 55 individuals with constitutive variants.

Wellcome Open Res 2018 23;3:46. Epub 2018 Apr 23.

Division of Genetics and Epidemiology, Institute of Cancer Research, London, UK.

Tatton-Brown-Rahman syndrome (TBRS; OMIM 615879), also known as the DNMT3A-overgrowth syndrome, is an overgrowth intellectual disability syndrome first described in 2014 with a report of 13 individuals with constitutive heterozygous variants. Here we have undertaken a detailed clinical study of 55 individuals with variants, including the 13 previously reported individuals. An intellectual disability and overgrowth were reported in >80% of individuals with TBRS and were designated major clinical associations. Additional frequent clinical associations (reported in 20-80% individuals) included an evolving facial appearance with low-set, heavy, horizontal eyebrows and prominent upper central incisors; joint hypermobility (74%); obesity (weight ³2SD, 67%); hypotonia (54%); behavioural/psychiatric issues (most frequently autistic spectrum disorder, 51%); kyphoscoliosis (33%) and afebrile seizures (22%). One individual was diagnosed with acute myeloid leukaemia in teenage years. Based upon the results from this study, we present our current management for individuals with TBRS.
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http://dx.doi.org/10.12688/wellcomeopenres.14430.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5964628PMC
April 2018

Histone Lysine Methylases and Demethylases in the Landscape of Human Developmental Disorders.

Am J Hum Genet 2018 01 21;102(1):175-187. Epub 2017 Dec 21.

Manchester Centre for Genomic Medicine, Division of Evolution & Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9WL, UK; Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester M13 9WL, UK. Electronic address:

Histone lysine methyltransferases (KMTs) and demethylases (KDMs) underpin gene regulation. Here we demonstrate that variants causing haploinsufficiency of KMTs and KDMs are frequently encountered in individuals with developmental disorders. Using a combination of human variation databases and existing animal models, we determine 22 KMTs and KDMs as additional candidates for dominantly inherited developmental disorders. We show that KMTs and KDMs that are associated with, or are candidates for, dominant developmental disorders tend to have a higher level of transcription, longer canonical transcripts, more interactors, and a higher number and more types of post-translational modifications than other KMT and KDMs. We provide evidence to firmly associate KMT2C, ASH1L, and KMT5B haploinsufficiency with dominant developmental disorders. Whereas KMT2C or ASH1L haploinsufficiency results in a predominantly neurodevelopmental phenotype with occasional physical anomalies, KMT5B mutations cause an overgrowth syndrome with intellectual disability. We further expand the phenotypic spectrum of KMT2B-related disorders and show that some individuals can have severe developmental delay without dystonia at least until mid-childhood. Additionally, we describe a recessive histone lysine-methylation defect caused by homozygous or compound heterozygous KDM5B variants and resulting in a recognizable syndrome with developmental delay, facial dysmorphism, and camptodactyly. Collectively, these results emphasize the significance of histone lysine methylation in normal human development and the importance of this process in human developmental disorders. Our results demonstrate that systematic clinically oriented pathway-based analysis of genomic data can accelerate the discovery of rare genetic disorders.
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http://dx.doi.org/10.1016/j.ajhg.2017.11.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5778085PMC
January 2018

Familial Ebstein Anomaly: Whole Exome Sequencing Identifies Novel Phenotype Associated With .

Circ Cardiovasc Genet 2017 Dec;10(6)

From the Wessex Clinical Genetics Service (C.L.M., I.K.T.) and Wessex Cardiac Unit (A.C., A.P.S.), University Hospital Southampton National Health Service Foundation Trust, United Kingdom; and Human Genetics and Genomic Medicine, Faculty of Medicine, University of Southampton, United Kingdom (G.A., I.K.T., S.E.).

Background: Familial Ebstein anomaly is a rare form of congenital heart disease. We report 7 individuals among 2 generations of 1 family with Ebstein anomaly. This family was first reported in 1991 by Balaji et al in which family members were also reported to have a mild skeletal phenotype. The most likely mechanism of inheritance was concluded to be autosomal dominant. We sought to identify the genetic pathogenesis in this family using a next generation sequencing approach.

Methods And Results: Whole exome sequencing was performed in 2 cousins in this family using the Agilent SureSelect Human all Exon 51 Mb version 5 capture kit. Data were processed through an analytic in-house pipeline. Whole exome sequencing identified a missense mutation in (Filamin A), an actin-binding protein located at Xq28, mutations in which are associated with the skeletal phenotypes Frontometaphyseal dysplasia, Otopalatodigital, and Melnick-Needles syndrome, with X-linked periventricular nodular heterotopia and FG syndrome (Omim, 305450). Review of the phenotypes of those with the mutation in this family shows increased severity of the cardiac phenotype and associated skeletal features in affected males, consistent with X-linked inheritance.

Conclusions: Although congenital heart disease is reported in families with mutations in , this is the first report of individuals being affected by Ebstein anomaly because of a mutation in this gene and details the concurrent skeletal phenotype observed in this family.
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http://dx.doi.org/10.1161/CIRCGENETICS.116.001683DOI Listing
December 2017

Human imprinting disorders: Principles, practice, problems and progress.

Eur J Med Genet 2017 Nov 14;60(11):618-626. Epub 2017 Aug 14.

Faculty of Medicine, University of Southampton, Duthie Building (MP808), Southampton University Hospital, Tremona Road, Southampton SO16 6YD, UK.

Epigenetic regulation orchestrates gene expression with exquisite precision, over a huge dynamic range and across developmental space and time, permitting genomically-homogeneous humans to develop and adapt to their surroundings. Every generation, these epigenetic marks are re-set twice: in the germline, to enable differentiation of sperm and eggs, and at fertilisation, to create the totipotent zygote that then begins growth and differentiation into a new human. A small group of genes evades the second, zygotic wave of epigenetic reprogramming, and these genes retain an epigenetic 'imprint' of the parent from whom they were inherited. Imprinted genes are (as a general rule) expressed from one parental allele only. Some imprinted genes are critical regulators of growth and development, and thus disruption of their normal monoallelic expression causes congenital imprinting disorders, with clinical features impacting growth, development, behaviour and metabolism. Imprinting disorders as a group have characteristics that challenge diagnosis and management, including clinical and molecular heterogeneity, overlapping clinical features, somatic mosaicism, and multi-locus involvement. New insights into the biology and epigenomics of the early embryo offers new clues about the origin and importance of imprinting disorders.
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http://dx.doi.org/10.1016/j.ejmg.2017.08.014DOI Listing
November 2017

Hypoinsulinaemic, hypoketotic hypoglycaemia due to mosaic genetic activation of PI3-kinase.

Eur J Endocrinol 2017 Aug 31;177(2):175-186. Epub 2017 May 31.

Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK.

Objective: Genetic activation of the insulin signal-transducing kinase causes syndromic hypoketotic hypoglycaemia without elevated insulin. Mosaic activating mutations in class 1A phospatidylinositol-3-kinase (PI3K), upstream from AKT2 in insulin signalling, are known to cause segmental overgrowth, but the metabolic consequences have not been systematically reported. We assess the metabolic phenotype of 22 patients with mosaic activating mutations affecting PI3K, thereby providing new insight into the metabolic function of this complex node in insulin signal transduction.

Methods: Three patients with megalencephaly, diffuse asymmetric overgrowth, hypoketotic, hypoinsulinaemic hypoglycaemia and no mutation underwent further genetic, clinical and metabolic investigation. Signalling in dermal fibroblasts from one patient and efficacy of the mTOR inhibitor Sirolimus on pathway activation were examined. Finally, the metabolic profile of a cohort of 19 further patients with mosaic activating mutations in PI3K was assessed.

Results: In the first three patients, mosaic mutations in (p.Gly118Asp or p.Glu726Lys) or (p.Gly373Arg) were found. In different tissue samples available from one patient, the p.Glu726Lys mutation was present at burdens from 24% to 42%, with the highest level in the liver. Dermal fibroblasts showed increased basal AKT phosphorylation which was potently suppressed by Sirolimus. Nineteen further patients with mosaic mutations in had neither clinical nor biochemical evidence of hypoglycaemia.

Conclusions: Mosaic mutations activating class 1A PI3K cause severe non-ketotic hypoglycaemia in a subset of patients, with the metabolic phenotype presumably related to the extent of mosaicism within the liver. mTOR or PI3K inhibitors offer the prospect for future therapy.
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http://dx.doi.org/10.1530/EJE-17-0132DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5488397PMC
August 2017

Mutations in Epigenetic Regulation Genes Are a Major Cause of Overgrowth with Intellectual Disability.

Am J Hum Genet 2017 May;100(5):725-736

Division of Genetics and Epidemiology, Institute of Cancer Research, 15 Cotswold Road, London SM2 5NG, UK; Cancer Genetics Unit, Royal Marsden NHS Foundation Trust, London SW3 6JJ, UK. Electronic address:

To explore the genetic architecture of human overgrowth syndromes and human growth control, we performed experimental and bioinformatic analyses of 710 individuals with overgrowth (height and/or head circumference ≥+2 SD) and intellectual disability (OGID). We identified a causal mutation in 1 of 14 genes in 50% (353/710). This includes HIST1H1E, encoding histone H1.4, which has not been associated with a developmental disorder previously. The pathogenic HIST1H1E mutations are predicted to result in a product that is less effective in neutralizing negatively charged linker DNA because it has a reduced net charge, and in DNA binding and protein-protein interactions because key residues are truncated. Functional network analyses demonstrated that epigenetic regulation is a prominent biological process dysregulated in individuals with OGID. Mutations in six epigenetic regulation genes-NSD1, EZH2, DNMT3A, CHD8, HIST1H1E, and EED-accounted for 44% of individuals (311/710). There was significant overlap between the 14 genes involved in OGID and 611 genes in regions identified in GWASs to be associated with height (p = 6.84 × 10), suggesting that a common variation impacting function of genes involved in OGID influences height at a population level. Increased cellular growth is a hallmark of cancer and there was striking overlap between the genes involved in OGID and 260 somatically mutated cancer driver genes (p = 1.75 × 10). However, the mutation spectra of genes involved in OGID and cancer differ, suggesting complex genotype-phenotype relationships. These data reveal insights into the genetic control of human growth and demonstrate that exome sequencing in OGID has a high diagnostic yield.
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http://dx.doi.org/10.1016/j.ajhg.2017.03.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5420355PMC
May 2017

Analysis of exome data for 4293 trios suggests GPI-anchor biogenesis defects are a rare cause of developmental disorders.

Eur J Hum Genet 2017 06 22;25(6):669-679. Epub 2017 Mar 22.

Department of Clinical Genetics, Oxford University Hospitals NHS Trust, Oxford, UK.

Over 150 different proteins attach to the plasma membrane using glycosylphosphatidylinositol (GPI) anchors. Mutations in 18 genes that encode components of GPI-anchor biogenesis result in a phenotypic spectrum that includes learning disability, epilepsy, microcephaly, congenital malformations and mild dysmorphic features. To determine the incidence of GPI-anchor defects, we analysed the exome data from 4293 parent-child trios recruited to the Deciphering Developmental Disorders (DDD) study. All probands recruited had a neurodevelopmental disorder. We searched for variants in 31 genes linked to GPI-anchor biogenesis and detected rare biallelic variants in PGAP3, PIGN, PIGT (n=2), PIGO and PIGL, providing a likely diagnosis for six families. In five families, the variants were in a compound heterozygous configuration while in a consanguineous Afghani kindred, a homozygous c.709G>C; p.(E237Q) variant in PIGT was identified within 10-12 Mb of autozygosity. Validation and segregation analysis was performed using Sanger sequencing. Across the six families, five siblings were available for testing and in all cases variants co-segregated consistent with them being causative. In four families, abnormal alkaline phosphatase results were observed in the direction expected. FACS analysis of knockout HEK293 cells that had been transfected with wild-type or mutant cDNA constructs demonstrated that the variants in PIGN, PIGT and PIGO all led to reduced activity. Splicing assays, performed using leucocyte RNA, showed that a c.336-2A>G variant in PIGL resulted in exon skipping and p.D113fs*2. Our results strengthen recently reported disease associations, suggest that defective GPI-anchor biogenesis may explain ~0.15% of individuals with developmental disorders and highlight the benefits of data sharing.
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http://dx.doi.org/10.1038/ejhg.2017.32DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5477361PMC
June 2017

Diagnosis and management of Silver-Russell syndrome: first international consensus statement.

Nat Rev Endocrinol 2017 02 2;13(2):105-124. Epub 2016 Sep 2.

AP-HP, Hôpitaux Universitaires Paris Est (AP-HP) Hôpital des Enfants Armand Trousseau, Service d'Explorations Fonctionnelles Endocriniennes, 26 avenue du Dr Arnold Netter, 75012 Paris, France.

This Consensus Statement summarizes recommendations for clinical diagnosis, investigation and management of patients with Silver-Russell syndrome (SRS), an imprinting disorder that causes prenatal and postnatal growth retardation. Considerable overlap exists between the care of individuals born small for gestational age and those with SRS. However, many specific management issues exist and evidence from controlled trials remains limited. SRS is primarily a clinical diagnosis; however, molecular testing enables confirmation of the clinical diagnosis and defines the subtype. A 'normal' result from a molecular test does not exclude the diagnosis of SRS. The management of children with SRS requires an experienced, multidisciplinary approach. Specific issues include growth failure, severe feeding difficulties, gastrointestinal problems, hypoglycaemia, body asymmetry, scoliosis, motor and speech delay and psychosocial challenges. An early emphasis on adequate nutritional status is important, with awareness that rapid postnatal weight gain might lead to subsequent increased risk of metabolic disorders. The benefits of treating patients with SRS with growth hormone include improved body composition, motor development and appetite, reduced risk of hypoglycaemia and increased height. Clinicians should be aware of possible premature adrenarche, fairly early and rapid central puberty and insulin resistance. Treatment with gonadotropin-releasing hormone analogues can delay progression of central puberty and preserve adult height potential. Long-term follow up is essential to determine the natural history and optimal management in adulthood.
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http://dx.doi.org/10.1038/nrendo.2016.138DOI Listing
February 2017

A Recurrent Mosaic Mutation in SMO, Encoding the Hedgehog Signal Transducer Smoothened, Is the Major Cause of Curry-Jones Syndrome.

Am J Hum Genet 2016 06 26;98(6):1256-1265. Epub 2016 May 26.

Clinical Genetics Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK. Electronic address:

Curry-Jones syndrome (CJS) is a multisystem disorder characterized by patchy skin lesions, polysyndactyly, diverse cerebral malformations, unicoronal craniosynostosis, iris colobomas, microphthalmia, and intestinal malrotation with myofibromas or hamartomas. Cerebellar medulloblastoma has been described in a single affected individual; in another, biopsy of skin lesions showed features of trichoblastoma. The combination of asymmetric clinical features, patchy skin manifestations, and neoplastic association previously led to the suggestion that this could be a mosaic condition, possibly involving hedgehog (Hh) signaling. Here, we show that CJS is caused by recurrent somatic mosaicism for a nonsynonymous variant in SMO (c.1234C>T [p.Leu412Phe]), encoding smoothened (SMO), a G-protein-coupled receptor that transduces Hh signaling. We identified eight mutation-positive individuals (two of whom had not been reported previously) with highly similar phenotypes and demonstrated varying amounts of the mutant allele in different tissues. We present detailed findings from brain MRI in three mutation-positive individuals. Somatic SMO mutations that result in constitutive activation have been described in several tumors, including medulloblastoma, ameloblastoma, and basal cell carcinoma. Strikingly, the most common of these mutations is the identical nonsynonymous variant encoding p.Leu412Phe. Furthermore, this substitution has been shown to activate SMO in the absence of Hh signaling, providing an explanation for tumor development in CJS. This raises therapeutic possibilities for using recently generated Hh-pathway inhibitors. In summary, our work uncovers the major genetic cause of CJS and illustrates strategies for gene discovery in the context of low-level tissue-specific somatic mosaicism.
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http://dx.doi.org/10.1016/j.ajhg.2016.04.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4908219PMC
June 2016

Genetic Analysis of 'PAX6-Negative' Individuals with Aniridia or Gillespie Syndrome.

PLoS One 2016 28;11(4):e0153757. Epub 2016 Apr 28.

MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom.

We report molecular genetic analysis of 42 affected individuals referred with a diagnosis of aniridia who previously screened as negative for intragenic PAX6 mutations. Of these 42, the diagnoses were 31 individuals with aniridia and 11 individuals referred with a diagnosis of Gillespie syndrome (iris hypoplasia, ataxia and mild to moderate developmental delay). Array-based comparative genomic hybridization identified six whole gene deletions: four encompassing PAX6 and two encompassing FOXC1. Six deletions with plausible cis-regulatory effects were identified: five that were 3' (telomeric) to PAX6 and one within a gene desert 5' (telomeric) to PITX2. Sequence analysis of the FOXC1 and PITX2 coding regions identified two plausibly pathogenic de novo FOXC1 missense mutations (p.Pro79Thr and p.Leu101Pro). No intragenic mutations were detected in PITX2. FISH mapping in an individual with Gillespie-like syndrome with an apparently balanced X;11 reciprocal translocation revealed disruption of a gene at each breakpoint: ARHGAP6 on the X chromosome and PHF21A on chromosome 11. In the other individuals with Gillespie syndrome no mutations were identified in either of these genes, or in HCCS which lies close to the Xp breakpoint. Disruption of PHF21A has previously been implicated in the causation of intellectual disability (but not aniridia). Plausibly causative mutations were identified in 15 out of 42 individuals (12/32 aniridia; 3/11 Gillespie syndrome). Fourteen of these mutations presented in the known aniridia genes; PAX6, FOXC1 and PITX2. The large number of individuals in the cohort with no mutation identified suggests greater locus heterogeneity may exist in both isolated and syndromic aniridia than was previously appreciated.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153757PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4849793PMC
February 2017

A Restricted Repertoire of De Novo Mutations in ITPR1 Cause Gillespie Syndrome with Evidence for Dominant-Negative Effect.

Am J Hum Genet 2016 05 21;98(5):981-992. Epub 2016 Apr 21.

MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK. Electronic address:

Gillespie syndrome (GS) is characterized by bilateral iris hypoplasia, congenital hypotonia, non-progressive ataxia, and progressive cerebellar atrophy. Trio-based exome sequencing identified de novo mutations in ITPR1 in three unrelated individuals with GS recruited to the Deciphering Developmental Disorders study. Whole-exome or targeted sequence analysis identified plausible disease-causing ITPR1 mutations in 10/10 additional GS-affected individuals. These ultra-rare protein-altering variants affected only three residues in ITPR1: Glu2094 missense (one de novo, one co-segregating), Gly2539 missense (five de novo, one inheritance uncertain), and Lys2596 in-frame deletion (four de novo). No clinical or radiological differences were evident between individuals with different mutations. ITPR1 encodes an inositol 1,4,5-triphosphate-responsive calcium channel. The homo-tetrameric structure has been solved by cryoelectron microscopy. Using estimations of the degree of structural change induced by known recessive- and dominant-negative mutations in other disease-associated multimeric channels, we developed a generalizable computational approach to indicate the likely mutational mechanism. This analysis supports a dominant-negative mechanism for GS variants in ITPR1. In GS-derived lymphoblastoid cell lines (LCLs), the proportion of ITPR1-positive cells using immunofluorescence was significantly higher in mutant than control LCLs, consistent with an abnormality of nuclear calcium signaling feedback control. Super-resolution imaging supports the existence of an ITPR1-lined nucleoplasmic reticulum. Mice with Itpr1 heterozygous null mutations showed no major iris defects. Purkinje cells of the cerebellum appear to be the most sensitive to impaired ITPR1 function in humans. Iris hypoplasia is likely to result from either complete loss of ITPR1 activity or structure-specific disruption of multimeric interactions.
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http://dx.doi.org/10.1016/j.ajhg.2016.03.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863663PMC
May 2016

Genome-wide DNA methylation analysis of transient neonatal diabetes type 1 patients with mutations in ZFP57.

BMC Med Genet 2016 Apr 14;17:29. Epub 2016 Apr 14.

Wilhelm Johannsen Center for Functional Genome Research, Institute of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, DK-2200, Copenhagen N, Denmark.

Background: Transient neonatal diabetes mellitus 1 (TNDM1) is a rare imprinting disorder characterized by intrautering growth retardation and diabetes mellitus usually presenting within the first six weeks of life and resolves by the age of 18 months. However, patients have an increased risk of developing diabetes mellitus type 2 later in life. Transient neonatal diabetes mellitus 1 is caused by overexpression of the maternally imprinted genes PLAGL1 and HYMAI on chromosome 6q24. One of the mechanisms leading to overexpression of the locus is hypomethylation of the maternal allele of PLAGL1 and HYMAI. A subset of patients with maternal hypomethylation at PLAGL1 have hypomethylation at additional imprinted loci throughout the genome, including GRB10, ZIM2 (PEG3), MEST (PEG1), KCNQ1OT1 and NESPAS (GNAS-AS1). About half of the TNDM1 patients carry mutations in ZFP57, a transcription factor involved in establishment and maintenance of methylation of imprinted loci. Our objective was to investigate whether additional regions are aberrantly methylated in ZFP57 mutation carriers.

Methods: Genome-wide DNA methylation analysis was performed on four individuals with homozygous or compound heterozygous ZFP57 mutations, three relatives with heterozygous ZFP57 mutations and five controls. Methylation status of selected regions showing aberrant methylation in the patients was verified using bisulfite-sequencing.

Results: We found large variability among the patients concerning the number and identity of the differentially methylated regions, but more than 60 regions were aberrantly methylated in two or more patients and a novel region within PPP1R13L was found to be hypomethylated in all the patients. The hypomethylated regions in common between the patients are enriched for the ZFP57 DNA binding motif.

Conclusions: We have expanded the epimutational spectrum of TNDM1 associated with ZFP57 mutations and found one novel region within PPP1R13L which is hypomethylated in all TNDM1 patients included in this study. Functional studies of the locus might provide further insight into the etiology of the disease.
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http://dx.doi.org/10.1186/s12881-016-0292-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4831126PMC
April 2016

Erratum to: Imprinting disorders: a group of congenital disorders with overlapping patterns of molecular changes affecting imprinted loci.

Clin Epigenetics 2016 7;8:27. Epub 2016 Mar 7.

Endocrinology and diabetology for children and reference center for rare disorders of calcium and phosphorus metabolism, Bicêtre Paris Sud, APHP, Le Kremlin-Bicêtre, France ; INSERM U986, INSERM, Le Kremlin-Bicêtre, France ; INSERM, UMR_S 938, CDR Saint-Antoine, Paris, F-75012 France.

[This corrects the article DOI: 10.1186/s13148-015-0143-8.].
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http://dx.doi.org/10.1186/s13148-016-0194-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4782320PMC
March 2016

Imprinting disorders: a group of congenital disorders with overlapping patterns of molecular changes affecting imprinted loci.

Clin Epigenetics 2015 14;7:123. Epub 2015 Nov 14.

Endocrinology and diabetology for children and reference center for rare disorders of calcium and phosphorus metabolism, Bicêtre Paris Sud, APHP, Le Kremlin-Bicêtre, France ; INSERM U986, INSERM, Le Kremlin-Bicêtre, France ; INSERM, UMR_S 938, CDR Saint-Antoine, Paris, F-75012 France.

Congenital imprinting disorders (IDs) are characterised by molecular changes affecting imprinted chromosomal regions and genes, i.e. genes that are expressed in a parent-of-origin specific manner. Recent years have seen a great expansion in the range of alterations in regulation, dosage or DNA sequence shown to disturb imprinted gene expression, and the correspondingly broad range of resultant clinical syndromes. At the same time, however, it has become clear that this diversity of IDs has common underlying principles, not only in shared molecular mechanisms, but also in interrelated clinical impacts upon growth, development and metabolism. Thus, detailed and systematic analysis of IDs can not only identify unifying principles of molecular epigenetics in health and disease, but also support personalisation of diagnosis and management for individual patients and families.
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http://dx.doi.org/10.1186/s13148-015-0143-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4650860PMC
November 2015

Prenatal molecular testing for Beckwith-Wiedemann and Silver-Russell syndromes: a challenge for molecular analysis and genetic counseling.

Eur J Hum Genet 2016 06 28;24(6):784-93. Epub 2015 Oct 28.

Instituto de Genética Médica y Molecular (INGEMM)-IdiPAZ, Hospital Universitario La Paz, Madrid, Spain.

Beckwith-Wiedemann and Silver-Russell syndromes (BWS/SRS) are two imprinting disorders (IDs) associated with disturbances of the 11p15.5 chromosomal region. In BWS, epimutations and genomic alterations within 11p15.5 are observed in >70% of patients, whereas in SRS they are observed in about 60% of the cases. In addition, 10% of the SRS patients carry a maternal uniparental disomy of chromosome 7 11p15.5. There is an increasing demand for prenatal testing of these disorders owing to family history, indicative prenatal ultrasound findings or aberrations involving chromosomes 7 and 11. The complex molecular findings underlying these disorders are a challenge not only for laboratories offering these tests but also for geneticists counseling affected families. The scope of counseling must consider the range of detectable disturbances and their origin, the lack of precise quantitative knowledge concerning the inheritance and recurrence risks for the epigenetic abnormalities, which are hallmarks of these developmental disorders. In this paper, experts in the field of BWS and SRS, including members of the European network of congenital IDs (EUCID.net; www.imprinting-disorders.eu), put together their experience and work in the field of 11p15.5-associated IDs with a focus on prenatal testing. Altogether, prenatal tests of 160 fetuses (122 referred for BWS, 38 for SRS testing) from 5 centers were analyzed and reviewed. We summarize the current knowledge on BWS and SRS with respect to diagnostic testing, the consequences for prenatal genetic testing and counseling and our cumulative experience in dealing with these disorders.
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http://dx.doi.org/10.1038/ejhg.2015.224DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4867462PMC
June 2016

Mandibulofacial Dysostosis with Microcephaly: Mutation and Database Update.

Hum Mutat 2016 Feb 19;37(2):148-54. Epub 2015 Nov 19.

The Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.

Mandibulofacial dysostosis with microcephaly (MFDM) is a multiple malformation syndrome comprising microcephaly, craniofacial anomalies, hearing loss, dysmorphic features, and, in some cases, esophageal atresia. Haploinsufficiency of a spliceosomal GTPase, U5-116 kDa/EFTUD2, is responsible. Here, we review the molecular basis of MFDM in the 69 individuals described to date, and report mutations in 38 new individuals, bringing the total number of reported individuals to 107 individuals from 94 kindreds. Pathogenic EFTUD2 variants comprise 76 distinct mutations and seven microdeletions. Among point mutations, missense substitutions are infrequent (14 out of 76; 18%) relative to stop-gain (29 out of 76; 38%), and splicing (33 out of 76; 43%) mutations. Where known, mutation origin was de novo in 48 out of 64 individuals (75%), dominantly inherited in 12 out of 64 (19%), and due to proven germline mosaicism in four out of 64 (6%). Highly penetrant clinical features include, microcephaly, first and second arch craniofacial malformations, and hearing loss; esophageal atresia is present in an estimated ∼27%. Microcephaly is virtually universal in childhood, with some adults exhibiting late "catch-up" growth and normocephaly at maturity. Occasionally reported anomalies, include vestibular and ossicular malformations, reduced mouth opening, atrophy of cerebral white matter, structural brain malformations, and epibulbar dermoid. All reported EFTUD2 mutations can be found in the EFTUD2 mutation database (http://databases.lovd.nl/shared/genes/EFTUD2).
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http://dx.doi.org/10.1002/humu.22924DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5512564PMC
February 2016

Temple syndrome as a result of isolated hypomethylation of the 14q32 imprinted DLK1/MEG3 region.

Am J Med Genet A 2016 Jan 23;170A(1):170-5. Epub 2015 Sep 23.

Academic Unit of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.

We present a Caucasian female, who was diagnosed at 13 years of age with Temple syndrome (formerly referred to as "maternal UPD 14 phenotype") due to an epigenetic loss of methylation at IG-DMR/MEG3-DMR at the chromosome 14q32 imprinted locus. Clinical features were typical and included intra-uterine growth retardation (IUGR), low birth weight, hypotonia, and poor feeding in the neonatal period; and failure to thrive and developmental delay--particularly in relation to speech--in early childhood. Premature puberty, with short stature and truncal obesity, but normal intelligence, were the key features in teenage years. To date only eight patients with Temple syndrome due to an epigenetic error have been described and the etiology of the methylation defect is currently undetermined. In view of a tendency towards central obesity, patients are at potential risk of early-onset type 2 diabetes mellitus, as well as cardiovascular disease and they, therefore, require appropriate monitoring.
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http://dx.doi.org/10.1002/ajmg.a.37400DOI Listing
January 2016

Mutations in NLRP5 are associated with reproductive wastage and multilocus imprinting disorders in humans.

Nat Commun 2015 Sep 1;6:8086. Epub 2015 Sep 1.

Academic Unit of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UK.

Human-imprinting disorders are congenital disorders of growth, development and metabolism, associated with disturbance of parent of origin-specific DNA methylation at imprinted loci across the genome. Some imprinting disorders have higher than expected prevalence of monozygotic twinning, of assisted reproductive technology among parents, and of disturbance of multiple imprinted loci, for which few causative trans-acting mutations have been found. Here we report mutations in NLRP5 in five mothers of individuals affected by multilocus imprinting disturbance. Maternal-effect mutations of other human NLRP genes, NLRP7 and NLRP2, cause familial biparental hydatidiform mole and multilocus imprinting disturbance, respectively. Offspring of mothers with NLRP5 mutations have heterogenous clinical and epigenetic features, but cases include a discordant monozygotic twin pair, individuals with idiopathic developmental delay and autism, and families affected by infertility and reproductive wastage. NLRP5 mutations suggest connections between maternal reproductive fitness, early zygotic development and genomic imprinting.
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http://dx.doi.org/10.1038/ncomms9086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4568303PMC
September 2015