scholarly journals Intricacies of aetiology in intrafamilial degenerative disease

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Jessica L Lowry ◽  
Éanna B Ryan ◽  
Y Taylan Esengul ◽  
Nailah Siddique ◽  
Teepu Siddique
Keyword(s):  
Disease Transmission ◽  
De Novo ◽  
Late Onset ◽  
Family Members ◽  
Degenerative Disease ◽  
De Novo Mutations ◽  
Pathogenic Variants ◽  
Disease Trait ◽  
Disease Aetiology

Abstract The genetic underpinnings of late-onset degenerative disease have typically been determined by screening families for the segregation of genetic variants with the disease trait in affected, but not unaffected, individuals. However, instances of intrafamilial etiological heterogeneity, where pathogenic variants in a culprit gene are not shared among all affected family members, continue to emerge and confound gene-discovery and genetic counselling efforts. Discordant intrafamilial cases lacking a mutation shared by other affected family members are described as disease phenocopies. This description often results in an over-simplified acceptance of an environmental cause of disease in the phenocopy cases, while the role of intrafamilial genetic heterogeneity, shared de novo mutations or epigenetic aberrations in such families is often ignored. On a related note, it is now evident that the same disease-associated variant can be present in individuals exhibiting clinically distinct phenotypes, thereby genetically uniting seemingly unrelated syndromes to form a spectrum of disease. Herein, we discuss the intricacies of determining complex degenerative disease aetiology and suggest alternative mechanisms of disease transmission that may account for the apparent missing heritability of disease.

scholarly journals Novel p.G1344E mutation in FBN1 is associated with ectopia lentis

2020 ◽  
pp. bjophthalmol-2019-315265
Author(s):  
Yuan Yang ◽  
Ya-li Zhou ◽  
Teng-teng Yao ◽  
Hui Pan ◽  
Ping Gu ◽  
...  
Keyword(s):  
Late Onset ◽  
Family Members ◽  
Crystalline Lens ◽  
Pathogenic Mutation ◽  
Ectopia Lentis ◽  
Skeletal Involvement ◽  
Suspensory Ligament ◽  
Pathogenic Variants ◽  
Fibrillin 1 ◽  
Systemic Examination

BackgroundEctopia lentis refers to dislocation or subluxation of the crystalline lens. Fibrillin-1, encoded by FBN1, is an important microfibrillar structural component that is specifically required for the suspensory ligament of the lens. FBN1 mutations may cause abnormal structure of microfibrils and has been associated with a broad spectrum of clinical phenotypes. In this study, we characterised a Chinese dominant family with late-onset isolated ectopia lentis caused by a novel missense FBN1 mutation.MethodsEight family members, including four patients with suspected isolated ectopia lentis, were recruited from Shanghai. Clinical data and family history of the proband and other affected family members were collected. Ophthalmic examination, systemic examination and echocardiography were performed. Whole exome sequencing and Sanger sequencing were used to detect potential pathogenic variants.ResultsA novel heterozygous missense mutation c.4031 G>A/p.Gly1344Glu in exon 33 of FBN1 was identified. This mutation was detected in all affected family members and led to specific ocular system phenotypes (ectopia lentis, microspherophakia and secondary glaucoma) with minor skeletal involvement (hallux valgus).ConclusionThe novel c.4031G>A mutation in FBN1 is a likely pathogenic mutation for isolated ectopia lentis. Our study expands the spectrum of FBN1 mutations and contributes to better comprehension of genotype-phenotype correlations of ectopia lentis disease.

scholarly journals A de novo paradigm for male infertility

2021 ◽  
Author(s):  
MS Oud ◽  
RM Smits ◽  
HE Smith ◽  
FK Mastrorosa ◽  
GS Holt ◽  
...  
Keyword(s):  
Male Infertility ◽  
De Novo ◽  
P Value ◽  
Missense Mutations ◽  
Loss Of Function ◽  
De Novo Mutations ◽  
Systematic Analysis ◽  
Significant Enrichment

IntroductionDe novo mutations (DNMs) are known to play a prominent role in sporadic disorders with reduced fitness1. We hypothesize that DNMs play an important role in male infertility and explain a significant fraction of the genetic causes of this understudied disorder. To test this hypothesis, we performed trio-based exome-sequencing in a unique cohort of 185 infertile males and their unaffected parents. Following a systematic analysis, 29 of 145 rare protein altering DNMs were classified as possibly causative of the male infertility phenotype. We observed a significant enrichment of Loss-of-Function (LoF) DNMs in LoF-intolerant genes (p-value=1.00×10-5) as well as predicted pathogenic missense DNMs in missense-intolerant genes (p-value=5.01×10-4). One DNM gene identified, RBM5, is an essential regulator of male germ cell pre-mRNA splicing2. In a follow-up study, 5 rare pathogenic missense mutations affecting this gene were observed in a cohort of 2,279 infertile patients, with no such mutations found in a cohort of 5,784 fertile men (p-value=0.009). Our results provide the first evidence for the role of DNMs in severe male infertility and point to many new candidate genes affecting fertility.

scholarly journals New insights into the generation and role of de novo mutations in health and disease

2016 ◽  
Vol 17 (1) ◽  
Author(s):  
Rocio Acuna-Hidalgo ◽  
Joris A. Veltman ◽  
Alexander Hoischen
Keyword(s):  
De Novo ◽  
De Novo Mutations ◽  
Health And Disease

scholarly journals Unexpected role of SIX1 variants in craniosynostosis: expanding the phenotype of SIX1-related disorders

2021 ◽  
pp. jmedgenet-2020-107459
Author(s):  
Eduardo Calpena ◽  
Maud Wurmser ◽  
Simon J McGowan ◽  
Rodrigo Atique ◽  
Débora R Bertola ◽  
...  
Keyword(s):  
De Novo ◽  
Population Data ◽  
Cranial Sutures ◽  
Loss Of Function ◽  
De Novo Mutations ◽  
Data Enrichment ◽  
Whole Exome ◽  
Lambdoid Synostosis ◽  
Suture Fusion

BackgroundPathogenic heterozygous SIX1 variants (predominantly missense) occur in branchio-otic syndrome (BOS), but an association with craniosynostosis has not been reported.MethodsWe investigated probands with craniosynostosis of unknown cause using whole exome/genome (n=628) or RNA (n=386) sequencing, and performed targeted resequencing of SIX1 in 615 additional patients. Expression of SIX1 protein in embryonic cranial sutures was examined in the Six1nLacZ/+ reporter mouse.ResultsFrom 1629 unrelated cases with craniosynostosis we identified seven different SIX1 variants (three missense, including two de novo mutations, and four nonsense, one of which was also present in an affected twin). Compared with population data, enrichment of SIX1 loss-of-function variants was highly significant (p=0.00003). All individuals with craniosynostosis had sagittal suture fusion; additionally four had bilambdoid synostosis. Associated BOS features were often attenuated; some carrier relatives appeared non-penetrant. SIX1 is expressed in a layer basal to the calvaria, likely corresponding to the dura mater, and in the mid-sagittal mesenchyme.ConclusionCraniosynostosis is associated with heterozygous SIX1 variants, with possible enrichment of loss-of-function variants compared with classical BOS. We recommend screening of SIX1 in craniosynostosis, particularly when sagittal±lambdoid synostosis and/or any BOS phenotypes are present. These findings highlight the role of SIX1 in cranial suture homeostasis.

scholarly journals Whole-genome Sequencing Reveals De-novo Mutations Associated with Nonsyndromic Cleft Lip/Palate

2021 ◽  
Author(s):  
Waheed Awotoye ◽  
Peter A. Mossey ◽  
Jacqueline B. Hetmanski ◽  
Lord Jephthah Joojo Gowans ◽  
Mekonen A. Eshete ◽  
...  
Keyword(s):  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Cleft Lip ◽  
De Novo ◽  
Association Studies ◽  
Whole Genome ◽  
Loss Of Function ◽  
De Novo Mutations ◽  
Pathogenic Variants ◽  
Cleft Lip Palate

Abstract The majority (85%) of nonsyndromic cleft lip with or without cleft palate (nsCL/P) cases occur sporadically, suggesting a role for de novo mutations (DNMs) in the etiology of nsCL/P. To identify high impact DNMs that contribute to the risk of nsCL/P, we conducted whole genome sequencing (WGS) analyses in 130 African case-parent trios (affected probands and unaffected parents). We identified 162 high confidence protein-altering DNMs that contribute to the risk of nsCL/P. These include novel loss-of-function DNMs in the ACTL6A, ARHGAP10, MINK1, TMEM5 and TTN genes; as well as missense variants in ACAN, DHRS3, DLX6, EPHB2, FKBP10, KMT2D, RECQL4, SEMA3C, SEMA4D, SHH, TP63, and TULP4. Experimental evidence showed that ACAN, DHRS3, DLX6, EPHB2, FKBP10, KMT2D, MINK1, RECQL4, SEMA3C, SEMA4D, SHH, TP63, and TTN genes contribute to facial development and mutations in these genes could contribute to CL/P. Association studies have identified TULP4 as a potential cleft candidate gene, while ARHGAP10 interacts with CTNNB1 to control WNT signaling. DLX6, EPHB2, SEMA3C and SEMA4D harbor novel damaging DNMs that may affect their role in neural crest migration and palatal development. This discovery of pathogenic DNMs also confirms the power of WGS analysis of trios in the discovery of potential pathogenic variants.

scholarly journals Genetics of Paroxysmal Dyskinesia: Novel Variants Corroborate the Role of KCNA1 in Paroxysmal Dyskinesia and Highlight the Diverse Phenotypic Spectrum of KCNA1- and SLC2A1-Related Disorders

2021 ◽  
Vol 12 ◽  
Author(s):  
Josua Kegele ◽  
Johanna Krüger ◽  
Mahmoud Koko ◽  
Lara Lange ◽  
Ana Victoria Marco Hernandez ◽  
...  
Keyword(s):  
De Novo ◽  
Case Series ◽  
Clinical Information ◽  
Paroxysmal Dyskinesia ◽  
Pathogenic Variants ◽  
Paroxysmal Kinesigenic Dyskinesia ◽  
Novel Variants ◽  
Technical Advances ◽  
Exercise Induced

Paroxysmal dyskinesias (PxD) are rare movement disorders with characteristic episodes of involuntary mixed hyperkinetic movements. Scientific efforts and technical advances in molecular genetics have led to the discovery of a variety of genes associated with PxD; however, clinical and genetic information of rarely affected genes or infrequent variants is often limited. In our case series, we present two individuals with PxD including one with classical paroxysmal kinesigenic dyskinesia, who carry new likely pathogenic de novo variants in KCNA1 (p.Gly396Val and p.Gly396Arg). The gene has only recently been discovered to be causative for familial paroxysmal kinesigenic dyskinesia. We also provide genetic evidence for pathogenicity of two newly identified disease-causing variants in SLC2A1 (p.Met96Thr and p.Leu231Pro) leading to paroxysmal exercise-induced dyskinesia. Since clinical information of carriers of variants in known disease-causing genes is often scarce, we encourage to share clinical data of individuals with rare or novel (likely) pathogenic variants to improve disease understanding.

scholarly journals Rare Variants in Complex Traits: Novel Identification Strategies and the Role of de novo Mutations

2012 ◽  
Vol 74 (3-4) ◽  
pp. 215-225 ◽  
Author(s):  
Loubna Jouan ◽  
Julie Gauthier ◽  
Patrick A. Dion ◽  
Guy A. Rouleau
Keyword(s):  
Complex Traits ◽  
Rare Variants ◽  
De Novo ◽  
De Novo Mutations

The Autism Spectrum

2018 ◽  
pp. 243-260
Author(s):  
Marco Del Giudice
Keyword(s):  
Risk Factors ◽  
De Novo ◽  
Autism Spectrum ◽  
Repetitive Behaviors ◽  
Evolutionary Models ◽  
De Novo Mutations ◽  
Life History Variation ◽  
New Directions ◽  
Developmental Features

The chapter discusses autism spectrum disorder (ASD). Autism is defined by a triad of symptoms: impairments in social interaction, impairments in communication, and restricted/repetitive behaviors and interests. After an overview of this disorder, its developmental features, and the main risk factors identified in the epidemiological literature, the chapter critically reviews existing evolutionary models and suggests new directions for research. The final section applies the criteria developed earlier in the book to classify the disorder within the fast-slow-defense (FSD) model and identify functionally distinct subtypes. The author proposes to distinguish between a slow spectrum subtype with normal or high IQ and a major role of common alleles (S-ASD) and a subtype unrelated to life history variation, with high rates of intellectual disability and a major role of rare and de novo mutations (O-ASD).

scholarly journals A de novo paradigm for male infertility

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
M. S. Oud ◽  
R. M. Smits ◽  
H. E. Smith ◽  
F. K. Mastrorosa ◽  
G. S. Holt ◽  
...  
Keyword(s):  
Male Infertility ◽  
De Novo ◽  
Missense Mutations ◽  
Loss Of Function ◽  
De Novo Mutations ◽  
Systematic Analysis ◽  
Significant Enrichment ◽  
Infertile Patients

AbstractDe novo mutations are known to play a prominent role in sporadic disorders with reduced fitness. We hypothesize that de novo mutations play an important role in severe male infertility and explain a portion of the genetic causes of this understudied disorder. To test this hypothesis, we utilize trio-based exome sequencing in a cohort of 185 infertile males and their unaffected parents. Following a systematic analysis, 29 of 145 rare (MAF < 0.1%) protein-altering de novo mutations are classified as possibly causative of the male infertility phenotype. We observed a significant enrichment of loss-of-function de novo mutations in loss-of-function-intolerant genes (p-value = 1.00 × 10−5) in infertile men compared to controls. Additionally, we detected a significant increase in predicted pathogenic de novo missense mutations affecting missense-intolerant genes (p-value = 5.01 × 10−4) in contrast to predicted benign de novo mutations. One gene we identify, RBM5, is an essential regulator of male germ cell pre-mRNA splicing and has been previously implicated in male infertility in mice. In a follow-up study, 6 rare pathogenic missense mutations affecting this gene are observed in a cohort of 2,506 infertile patients, whilst we find no such mutations in a cohort of 5,784 fertile men (p-value = 0.03). Our results provide evidence for the role of de novo mutations in severe male infertility and point to new candidate genes affecting fertility.

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