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1.
Artigo em Inglês | MEDLINE | ID: mdl-31653659

RESUMO

Uniparental isodisomy (UPiD) is a rare genetic event that occurs when two identical copies of a single chromosome are inherited from one parent. Here we report a patient with a severe, multisystem metabolic disorder who inherited two copies of chromosome 12 from her father. He was a heterozygous carrier of a variant in the muscle-specific enzyme 6-phosphofructokinase (PFKM) gene, and of a truncating variant in the pseudouridine synthase 1 (PUS1) gene (both on chromosome 12), resulting in a homozygous state of these mutations in his daughter. The PFKM gene functions in glycolysis and is linked to Tarui syndrome. The PUS1 gene functions in mitochondrial tRNA processing and is linked to myopathy, lactic acidosis, and sideroblastic anemia (MLASA). Analysis of human dermal fibroblasts, which do not express PFKM, revealed a loss of PUS1 mRNA and PUS1 protein only in the patient cells compared to healthy controls. The patient cells also revealed a reduction of the mitochondrial-encoded protein MTCO1 while levels of the nuclear-encoded SDHA remained unchanged, suggesting a specific impairment of mitochondrial translation. Further destabilization of these cells is suggested by the altered levels of BAX, BCL-2, and TP53 proteins, alterations that become augmented upon exposure of the cells to DNA damage. The results illustrate the efficacy of UPiD events to reveal rare pathogenic variants in human disease, and demonstrate how these events can lead to cellular destabilization.

2.
Mol Genet Metab ; 126(1): 14-22, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30563741

RESUMO

BACKGROUND: A substantial number of severely debilitating and often ultimately fatal inborn errors of metabolism (IEMs) still lack an effective disease-modifying treatment. Informing couples before a pregnancy about an increased risk of having a child with an inherited disorder is now feasible by preconception expanded carrier screening (ECS). While knowledge about carrier status enhances reproductive autonomy, it may also result in ethical dilemmas. The purpose of this study was to assess the attitudes of the general Dutch population towards preconception ECS and to investigate which factors influence these attitudes. METHODS: Data collection was carried out in collaboration with a market research agency. In total, 1188 Dutch individuals of reproductive age (18-45 years) were invited by email to complete an online ECS questionnaire in 2016. Prior to the start of the questionnaire, a written explanation of the concepts of autosomal recessive (AR) inheritance, carrier status and ECS was presented. RESULTS: The questionnaire was completed by 781 individuals (65.7%), of whom 31% indicated they would take an ECS test themselves. In addition, 55% agreed that ECS should be offered to all prospective parents. The most frequently selected argument in favor of ECS (47.2%) was that participants want to spare a child from a life with a severe hereditary disorder. The reason most often mentioned not to participate in ECS (48%) was that participants reported not having a hereditary disorder in the family. The majority preferred receiving individual test results above a couple-based disclosure method in which participants receive the carrier status results only when they are a carrier couple of the same disorder. Participants with religious beliefs were less likely to participate in ECS, whereas participants who were considering a (future) pregnancy were more likely to participate. CONCLUSION: Our study demonstrates an overall positive attitude among participants of reproductive age in the general Dutch population towards preconception ECS. A striking misconception is that many of the participants believe that ECS is of interest only for those with a positive family history of one of the hereditary disorders. This finding emphasizes the importance of providing understandable, balanced information and education to the general public regarding the concepts of inheritance when presenting the option of carrier screening. Our results provide valuable insights that can be used in the debate about the responsible implementation of preconception ECS for AR disorders, including IEMs.


Assuntos
Triagem de Portadores Genéticos , Conhecimentos, Atitudes e Prática em Saúde , Erros Inatos do Metabolismo/diagnóstico , Adolescente , Adulto , Feminino , Aconselhamento Genético , Testes Genéticos , Humanos , Masculino , Erros Inatos do Metabolismo/genética , Pessoa de Meia-Idade , Países Baixos , Pais , Cuidado Pré-Concepcional , Gravidez , Estudos Prospectivos , Religião , Inquéritos e Questionários , Adulto Jovem
3.
Am J Hum Genet ; 103(5): 752-768, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30388402

RESUMO

The nuclear factor I (NFI) family of transcription factors play an important role in normal development of multiple organs. Three NFI family members are highly expressed in the brain, and deletions or sequence variants in two of these, NFIA and NFIX, have been associated with intellectual disability (ID) and brain malformations. NFIB, however, has not previously been implicated in human disease. Here, we present a cohort of 18 individuals with mild ID and behavioral issues who are haploinsufficient for NFIB. Ten individuals harbored overlapping microdeletions of the chromosomal 9p23-p22.2 region, ranging in size from 225 kb to 4.3 Mb. Five additional subjects had point sequence variations creating a premature termination codon, and three subjects harbored single-nucleotide variations resulting in an inactive protein as determined using an in vitro reporter assay. All individuals presented with additional variable neurodevelopmental phenotypes, including muscular hypotonia, motor and speech delay, attention deficit disorder, autism spectrum disorder, and behavioral abnormalities. While structural brain anomalies, including dysgenesis of corpus callosum, were variable, individuals most frequently presented with macrocephaly. To determine whether macrocephaly could be a functional consequence of NFIB disruption, we analyzed a cortex-specific Nfib conditional knockout mouse model, which is postnatally viable. Utilizing magnetic resonance imaging and histology, we demonstrate that Nfib conditional knockout mice have enlargement of the cerebral cortex but preservation of overall brain structure and interhemispheric connectivity. Based on our findings, we propose that haploinsufficiency of NFIB causes ID with macrocephaly.

4.
Artigo em Inglês | MEDLINE | ID: mdl-30485715

RESUMO

BACKGROUND: Pathogenic variants in FBN1 cause autosomal dominant Marfan syndrome but can also be found in patients presenting with apparently isolated features of Marfan syndrome. Moreover, several families with autosomal recessive Marfan syndrome caused by pathogenic variants in FBN1 have been described. The aim of this report was to underline the clinical variability that can be associated with the pathogenic variant c.1453C>T, p.(Arg485Cys) in FBN1. METHODS: We provide the clinical details of two autosomal dominant families with this specific FBN1 variant, which was previously associated with autosomal recessive Marfan syndrome. RESULTS: Clinical data of 14 individuals carrying this variant from these two families were collected retrospectively. In both families, the diagnosis of autosomal dominant Marfan syndrome was established based on the characteristics of the variant and the phenotype which includes aortic aneurysms and dissections. Of interest, in one of the families, multiple relatives were diagnosed with early onset abdominal aortic aneurysms. CONCLUSION: In conclusion, FBN1 variant c.1453C>T, p.(Arg485Cys) is a pathogenic variant that can cause autosomal dominant Marfan syndrome characterized by a high degree of clinical variability and apparently isolated early onset familial abdominal aortic aneurysms.

5.
Genet Med ; 2018 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-30245513

RESUMO

PURPOSE: Pathogenic variants in KAT6A have recently been identified as a cause of syndromic developmental delay. Within 2 years, the number of patients identified with pathogenic KAT6A variants has rapidly expanded and the full extent and variability of the clinical phenotype has not been reported. METHODS: We obtained data for patients with KAT6A pathogenic variants through three sources: treating clinicians, an online family survey distributed through social media, and a literature review. RESULTS: We identified 52 unreported cases, bringing the total number of published cases to 76. Our results expand the genotypic spectrum of pathogenic variants to include missense and splicing mutations. We functionally validated a pathogenic splice-site variant and identified a likely hotspot location for de novo missense variants. The majority of clinical features in KAT6A syndrome have highly variable penetrance. For core features such as intellectual disability, speech delay, microcephaly, cardiac anomalies, and gastrointestinal complications, genotype- phenotype correlations show that late-truncating pathogenic variants (exons 16-17) are significantly more prevalent. We highlight novel associations, including an increased risk of gastrointestinal obstruction. CONCLUSION: Our data expand the genotypic and phenotypic spectrum for individuals with genetic pathogenic variants in KAT6A and we outline appropriate clinical management.

6.
J Community Genet ; 2018 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-30229537

RESUMO

A Dutch university hospital started offering cystic fibrosis (CF) carrier screening directly to consumers (DTC) through their website in 2010. A 6-year process evaluation was conducted to evaluate the offer. Screening was implemented as intended. However, uptake was lower than expected. Forty-four tests have been requested, partly by couples with a positive family history for CF, which was not the intended target group. Users were generally positive about the screening offer, citing accessibility, ease of testing, anonymity, and perceived shortcomings of regular healthcare as reasons for requesting screening. DTC CF carrier screening via a university hospital website is feasible, but is seldom used. Considering technological advances, continuation of this specific offer is questionable.

7.
Am J Hum Genet ; 102(6): 1195-1203, 2018 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-29861108

RESUMO

Next-generation sequencing is a powerful tool for the discovery of genes related to neurodevelopmental disorders (NDDs). Here, we report the identification of a distinct syndrome due to de novo or inherited heterozygous mutations in Tousled-like kinase 2 (TLK2) in 38 unrelated individuals and two affected mothers, using whole-exome and whole-genome sequencing technologies, matchmaker databases, and international collaborations. Affected individuals had a consistent phenotype, characterized by mild-borderline neurodevelopmental delay (86%), behavioral disorders (68%), severe gastro-intestinal problems (63%), and facial dysmorphism including blepharophimosis (82%), telecanthus (74%), prominent nasal bridge (68%), broad nasal tip (66%), thin vermilion of the upper lip (62%), and upslanting palpebral fissures (55%). Analysis of cell lines from three affected individuals showed that mutations act through a loss-of-function mechanism in at least two case subjects. Genotype-phenotype analysis and comparison of computationally modeled faces showed that phenotypes of these and other individuals with loss-of-function variants significantly overlapped with phenotypes of individuals with other variant types (missense and C-terminal truncating). This suggests that haploinsufficiency of TLK2 is the most likely underlying disease mechanism, leading to a consistent neurodevelopmental phenotype. This work illustrates the power of international data sharing, by the identification of 40 individuals from 26 different centers in 7 different countries, allowing the identification, clinical delineation, and genotype-phenotype evaluation of a distinct NDD caused by mutations in TLK2.

8.
J Inherit Metab Dis ; 41(5): 897-898, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29464431

RESUMO

Mutations in the SEPSECS gene are associated with pontocerebellar hypoplasia type 2D. Pontocerebellar hypoplasia (PCH) is a heterogeneous group of rare autosomal recessive neurodegenerative disorders, mainly affecting pons and cerebellum. Patients have severe motor and cognitive impairments and often die during infancy. Here, we report a 23-year-old woman with slowly progressive cerebellar ataxia and cognitive impairment, in whom a homozygous missense mutation in the SEPSECS gene (c.1321G>A; p.Gly441Arg) was identified with whole exome sequencing. Our findings underline that defects in selenoprotein synthesis can also result in milder cerebellar atrophy presenting at a later age.

9.
Eur J Hum Genet ; 26(2): 166-175, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29321671

RESUMO

Technological developments have enabled carrier screening for multiple disorders. This study evaluated experiences with a preconception carrier screening offer for four recessive disorders in a Dutch founder population. Questionnaires were completed by 182 attendees pretesting and posttesting and by 137 non-attendees. Semistructured interviews were conducted with seven of the eight carrier couples. Attendees were mainly informed about the existence of screening by friends/colleagues (49%) and family members (44%). Familiarity with the genetic disorders was high. Knowledge after counseling increased (p < 0.001); however, still 9%, compared to 29% before counseling, wrongly mentioned an increased risk of having an affected child if both parents are carriers of different disorders. Most attendees (97%) recalled their test results correctly, but two couples reported being carrier of another disorder than reported. Overall, 63% felt worried while waiting for results but anxiety levels returned to normal afterwards. In all, 2/39 (5%) carriers felt less healthy. Screened individuals were very satisfied; they did not regret testing (97%) and would recommend testing to others (97%). The majority (94%) stated that couples should always have a pretest consultation, preferably by a genetic counselor rather than their general practitioner (83%). All carrier couples made reproductive decisions based on their results. Main reason for non-attendance was unawareness of the screening offer. With expanded carrier screening, adequately informing couples pretest and posttesting is of foremost importance. Close influencers (family/friends) can be used to raise awareness of a screening offer. Our findings provide lessons for the implementation of expanded carrier screening panels in other communities and other settings.

10.
J Genet Couns ; 27(3): 635-646, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28980104

RESUMO

Carrier screening for hemoglobinopathies (HbPs; sickle cell disease and thalassemia) aims to facilitate autonomous reproductive decision-making. In the absence of a Dutch national HbP carrier screening program, some primary care midwives offer screening on an ad hoc basis. This qualitative descriptive study explores how pregnant women perceive an offer of HbP carrier screening by their midwife. Semi-structured interviews (n = 26) were conducted with pregnant women at risk of being a HbP carrier, and whom were offered screening at their booking appointment in one of two midwifery practices in Amsterdam. The results showed that half of the respondents were familiar with HbPs. Generally, women perceived the offer of HbP carrier screening as positive, and most women (n = 19) accepted screening. Seven declined, of whom two already knew their carrier status. Important reasons to accept screening were to obtain knowledge about their own carrier status and health of their unborn child, and the ease of the procedure. A multistep process of decision-making was observed, as many women did not give follow-up testing (e.g. partner, invasive diagnostics) much consideration while deciding on accepting or declining HbP screening. Women experienced information overload, and preferred receiving the information at a different moment (e.g. before the intake by a leaflet, or preconceptionally). In conclusion, while prenatal HbP carrier screening is perceived as positive, informed decision-making seems to be suboptimal, and both the content and timing of the information provided needs improvement.

11.
Eur J Med Genet ; 61(2): 94-97, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29056561

RESUMO

Bloom syndrome is an autosomal recessive condition characterized by severe pre- and postnatal growth deficiency, immunodeficiency, an increased risk for malignancies, craniofacial dysmorphisms, and "typical" erythematous sun-sensitive skin lesions of the face. This facial rash has a butterfly-shaped distribution around the nose and is usually observed for the first time during the early years of life. Though reported as being a main feature of Bloom syndrome, there seems to be phenotypic variability regarding this facial skin rash among patients. It has been previously reported that in some individuals with Bloom syndrome these sun-sensitive lesions are less prominent or even absent. In this report we describe a 36 year old woman with short stature, microcephaly, several dysmorphisms, congenital hypothyroidism and premature ovarian failure. She was diagnosed with nasopharyngeal carcinoma at 36 years of age, only a few months after her consultation at the department of Clinical Genetics. Whole Exome Sequencing demonstrated that she had Bloom syndrome caused by a compound heterozygous mutation in BLM (c.2207_2212delinsTAGATTC; p.(Tyr736Leufs*5) and c.3681del; p.(Lys1227Asnfs*52)). She did not have facial sun-sensitive erythematous rash during childhood nor adulthood. We conclude that Bloom syndrome does not always present with erythematous sun-sensitive skin lesions of the face. We would like to underline that phenotypic variation regarding this "hallmark" feature of Bloom syndrome exists. Being aware of this might prevent a delay in diagnosing this rare short-stature syndrome and, subsequently, its potential clinical implications.


Assuntos
Síndrome de Bloom/patologia , Eritema/patologia , Fenótipo , Adulto , Síndrome de Bloom/genética , Diagnóstico Diferencial , Eritema/etiologia , Eritema/genética , Feminino , Humanos , RecQ Helicases/genética , Luz Solar/efeitos adversos
13.
Am J Med Genet A ; 173(8): 2108-2125, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28548707

RESUMO

SMC1A encodes one of the proteins of the cohesin complex. SMC1A variants are known to cause a phenotype resembling Cornelia de Lange syndrome (CdLS). Exome sequencing has allowed recognizing SMC1A variants in individuals with encephalopathy with epilepsy who do not resemble CdLS. We performed an international, interdisciplinary study on 51 individuals with SMC1A variants for physical and behavioral characteristics, and compare results to those in 67 individuals with NIPBL variants. For the Netherlands all known individuals with SMC1A variants were studied, both with and without CdLS phenotype. Individuals with SMC1A variants can resemble CdLS, but manifestations are less marked compared to individuals with NIPBL variants: growth is less disturbed, facial signs are less marked (except for periocular signs and thin upper vermillion), there are no major limb anomalies, and they have a higher level of cognitive and adaptive functioning. Self-injurious behavior is more frequent and more severe in the NIPBL group. In the Dutch group 5 of 13 individuals (all females) had a phenotype that shows a remarkable resemblance to Rett syndrome: epileptic encephalopathy, severe or profound intellectual disability, stereotypic movements, and (in some) regression. Their missense, nonsense, and frameshift mutations are evenly spread over the gene. We conclude that SMC1A variants can result in a phenotype resembling CdLS and a phenotype resembling Rett syndrome. Resemblances between the SMC1A group and the NIPBL group suggest that a disturbed cohesin function contributes to the phenotype, but differences between these groups may also be explained by other underlying mechanisms such as moonlighting of the cohesin genes.


Assuntos
Proteínas de Ciclo Celular/genética , Proteínas Cromossômicas não Histona/genética , Síndrome de Lange/genética , Proteínas/genética , Síndrome de Rett/genética , Adolescente , Adulto , Criança , Pré-Escolar , Síndrome de Lange/diagnóstico , Síndrome de Lange/fisiopatologia , Exoma/genética , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Síndrome de Rett/diagnóstico , Síndrome de Rett/fisiopatologia , Espasmos Infantis/diagnóstico , Espasmos Infantis/genética , Espasmos Infantis/fisiopatologia , Adulto Jovem
14.
BMC Health Serv Res ; 17(1): 146, 2017 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-28209157

RESUMO

BACKGROUND: In most countries, genetic carrier screening is neither offered, nor embedded in mainstream healthcare. Technological developments have triggered a two-fold transition in carrier screening: the expansion from screening one single disorder to many disorders simultaneously, and offering screening universally, regardless of ancestry. This study aims to identify general and population-specific barriers and needs reflected by stakeholders regarding the implementation of carrier screening in a changing landscape. METHODS: Seventeen semi-structured interviews were conducted with Dutch key stakeholders working in the practical and scientific field of carrier screening. The constellation approach was used to categorise barriers and needs into three levels: culture, structure and practice. RESULTS: Barriers on a cultural level include: undecidedness about the desirability of carrier screening, and a lack of priority of screening in mainstream healthcare. On a structural level barriers included: need for organisational structures in healthcare for embedding carrier screening, need for guidelines, financial structures, practical tools for overcoming challenges during counselling, and a need for training and education of both professionals and the public. A lack of demand for screening by the public, and a need for a division of responsibilities were barriers on a practical level. CONCLUSION: The absence of a collective sense of urgency for genetic carrier screening, a lack of organisational structures, and uncertainty or even disagreement about the responsibilities seem to be important barriers in the implementation of carrier screening. Stakeholders therefore suggest that change agents should be formally acknowledged to strategically plan broadening of current initiatives and attune different stakeholders.


Assuntos
Doenças Genéticas Inatas/prevenção & controle , Testes Genéticos , Heterozigoto , Atitude do Pessoal de Saúde , Atitude Frente a Saúde , Assistência à Saúde/organização & administração , Triagem de Portadores Genéticos/métodos , Doenças Genéticas Inatas/genética , Humanos , Programas de Rastreamento/organização & administração , Motivação , Determinação de Necessidades de Cuidados de Saúde , Países Baixos
15.
Eur J Public Health ; 27(2): 372-377, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-27485720

RESUMO

Background: Carrier screening for autosomal recessive disorders aims to facilitate reproductive decision-making by identifying couples with a 1-in-4 risk in every pregnancy of having an affected child. Except for a few countries or regions, carrier screening is not widely offered and is mostly ancestry-based. Technological advances enable carrier screening for multiple diseases simultaneously allowing universal screening regardless of ancestry (population-based expanded carrier screening). It is important to study how this can be successfully implemented. This study therefore aims to identify critical factors involved in successful implementation, from a user perspective, by learning from already implemented initiatives. Methods: Factors associated with successful implementation were identified by: (i) a literature review and (ii) two case studies; studying experiences with carrier screening in two high-risk communities (a Dutch founder population and the Ashkenazi Jewish population), including a survey among community members. Results: Factors identified were familiarity with (specific) genetic diseases and its availability, high perceived benefits of screening (e.g. screening avoids much suffering), acceptance of reproductive options, perceived risk of being a carrier and low perceived social barriers (e.g. stigmatization). In contrast to the Jewish community, the initial demand for screening in the Dutch founder population did not entirely come from the community itself. However, the large social cohesion of the community facilitated the implementation process. Conclusion: To ensure successful implementation of population-based expanded carrier screening, efforts should be made to increase knowledge about genetic diseases, create awareness and address personal benefits of screening in a non-directive way.


Assuntos
Testes Genéticos/métodos , Heterozigoto , Programas de Rastreamento/métodos , Adolescente , Adulto , Feminino , Humanos , Judeus/genética , Masculino , Países Baixos , Adulto Jovem
16.
Eur J Hum Genet ; 24(6): e1-e12, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26980105

RESUMO

This document of the European Society of Human Genetics contains recommendations regarding responsible implementation of expanded carrier screening. Carrier screening is defined here as the detection of carrier status of recessive diseases in couples or persons who do not have an a priori increased risk of being a carrier based on their or their partners' personal or family history. Expanded carrier screening offers carrier screening for multiple autosomal and X-linked recessive disorders, facilitated by new genetic testing technologies, and allows testing of individuals regardless of ancestry or geographic origin. Carrier screening aims to identify couples who have an increased risk of having an affected child in order to facilitate informed reproductive decision making. In previous decades, carrier screening was typically performed for one or few relatively common recessive disorders associated with significant morbidity, reduced life-expectancy and often because of a considerable higher carrier frequency in a specific population for certain diseases. New genetic testing technologies enable the expansion of screening to multiple conditions, genes or sequence variants. Expanded carrier screening panels that have been introduced to date have been advertised and offered to health care professionals and the public on a commercial basis. This document discusses the challenges that expanded carrier screening might pose in the context of the lessons learnt from decades of population-based carrier screening and in the context of existing screening criteria. It aims to contribute to the public and professional discussion and to arrive at better clinical and laboratory practice guidelines.


Assuntos
Aconselhamento Genético/psicologia , Testes Genéticos/normas , Heterozigoto , Guias de Prática Clínica como Assunto , Tomada de Decisões , Europa (Continente) , Aconselhamento Genético/ética , Testes Genéticos/ética , Genética Médica/ética , Genética Médica/organização & administração , Humanos , Sociedades Médicas
17.
Eur J Hum Genet ; 24(2): 171-7, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25966636

RESUMO

Ancestry-based carrier screening in the Ashkenazi Jewish population entails screening for specific autosomal recessive founder mutations, which are rarer among the general population. As it is now technically feasible to screen for many more diseases, the question arises whether this population prefers a limited ancestry-based offer or a pan-ethnic expanded carrier screening panel that goes beyond the diseases that are frequent in their own population, and is offered regardless of ancestry. An online questionnaire was completed by 145 individuals from the Dutch Jewish community (≥ 18 years) between April and July 2014. In total, 64.8% were aware of the existence of ancestry-based carrier screening, and respondents were generally positive about screening. About half (53.8%) preferred pan-ethnic expanded carrier screening, whereas 42.8% preferred ancestry-based screening. Reasons for preferring pan-ethnic screening included 'everyone has a right to be tested', 'fear of stigmatization when offering ancestry-based panels', and 'difficulties with identifying risk owing to mixed backgrounds'. 'Preventing high healthcare costs' was the most important reason against pan-ethnic carrier screening among those in favor of an ancestry-based panel. In conclusion, these findings show that people from the Dutch Jewish community have a positive attitude regarding carrier screening in their community for a wide range of diseases. As costs of expanded carrier screening panels are most likely to drop in the near future, it is expected that these panels will receive more support in the future.


Assuntos
Doenças Genéticas Inatas/genética , Testes Genéticos , Heterozigoto , Judeus/genética , Adolescente , Adulto , Idoso , Feminino , Efeito Fundador , Triagem de Portadores Genéticos , Doenças Genéticas Inatas/epidemiologia , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos , Gravidez , Diagnóstico Pré-Natal , Inquéritos e Questionários
18.
Eur J Med Genet ; 58(3): 123-8, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25641760

RESUMO

In a genetically isolated community in the Netherlands four severe recessive genetic disorders occur at relatively high frequency (pontocerebellar hypoplasia type 2 (PCH2), fetal akinesia deformation sequence (FADS), rhizomelic chondrodysplasia punctata type 1 (RCDP1), and osteogenesis imperfecta (OI) type IIB/III. Over the past decades multiple patients with these disorders have been identified. This warranted the start of a preconception outpatient clinic, in 2012, aimed at couples planning a pregnancy. The aim of our study was to evaluate the offer of targeted genetic carrier screening as a method to identify high-risk couples for having affected offspring in this high-risk subpopulation. In one year, 203 individuals (92 couples and 19 individuals) were counseled. In total, 65 of 196 (33.2%) tested individuals were carriers of at least one disease, five (7.7%) of them being carriers of two diseases. Carrier frequencies of PCH2, FADS, RCDP1, and OI were 14.3%, 11.2%, 6.1%, and 4.1% respectively. In individuals with a positive family history for one of the diseases, the carrier frequency was 57.8%; for those with a negative family history this was 25.8%. Four PCH2 carrier-couples were identified. Thus, targeted (preconception) carrier screening in this genetically isolated population in which a high prevalence of specific disorders occurs detects a high number of carriers, and is likely to be more effective compared to cascade genetic testing. Our findings and set-up can be seen as a model for carrier screening in other high-risk subpopulations and contributes to the discussion about the way carrier screening can be offered and organized in the general population.


Assuntos
Genes Recessivos , Triagem de Portadores Genéticos/métodos , Testes Genéticos/métodos , Adolescente , Adulto , Artrogripose/diagnóstico , Artrogripose/genética , Condrodisplasia Punctata Rizomélica/diagnóstico , Condrodisplasia Punctata Rizomélica/genética , Feminino , Efeito Fundador , Aconselhamento Genético , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos , Atrofias Olivopontocerebelares/diagnóstico , Atrofias Olivopontocerebelares/genética , Osteogênese Imperfeita/diagnóstico , Osteogênese Imperfeita/genética , Linhagem , Gravidez , Adulto Jovem
19.
Am J Hum Genet ; 93(6): 1143-50, 2013 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-24290379

RESUMO

Foveal hypoplasia and optic nerve misrouting are developmental defects of the visual pathway and only co-occur in connection with albinism; to date, they have only been associated with defects in the melanin-biosynthesis pathway. Here, we report that these defects can occur independently of albinism in people with recessive mutations in the putative glutamine transporter gene SLC38A8. Nine different mutations were identified in seven Asian and European families. Using morpholino-mediated ablation of Slc38a8 in medaka fish, we confirmed that pigmentation is unaffected by loss of SLC38A8. Furthermore, by undertaking an association study with SNPs at the SLC38A8 locus, we showed that common variants within this gene modestly affect foveal thickness in the general population. This study reveals a melanin-independent component underpinning the development of the visual pathway that requires a functional role for SLC38A8.


Assuntos
Albinismo , Sistemas de Transporte de Aminoácidos Neutros/genética , Fóvea Central/anormalidades , Genes Recessivos , Mutação , Nervo Óptico/fisiopatologia , Animais , Criança , Consanguinidade , Análise Mutacional de DNA , Feminino , Homozigoto , Humanos , Masculino , Linhagem , Fenótipo , Síndrome
20.
Hum Mutat ; 34(11): 1486-9, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24000151

RESUMO

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by stereotyped missense mutations in NOTCH3. Whether these mutations lead to the CADASIL phenotype via a neomorphic effect, or rather by a hypomorphic effect, is subject of debate. Here, we report two novel NOTCH3 mutations, both leading to a premature stop codon with predicted loss of NOTCH3 function. The first mutation, c.307C>T, p.Arg103*, was detected in two brothers aged 50 and 55 years, with a brain MRI and skin biopsy incompatible with CADASIL. The other mutation was found in a 40-year-old CADASIL patient compound heterozygous for a pathogenic NOTCH3 mutation (c.2129A>G, p.Tyr710Cys) and an intragenic frameshift deletion. The deletion was inherited from his father, who did not have the skin biopsy abnormalities seen in CADASIL patients. These individuals with rare NOTCH3 mutations indicate that hypomorphic NOTCH3 alleles do not cause CADASIL.


Assuntos
Alelos , CADASIL/diagnóstico , CADASIL/genética , Fenótipo , Receptores Notch/genética , Adulto , Encéfalo/patologia , Análise Mutacional de DNA , Heterozigoto , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Linhagem , Receptor Notch3 , Deleção de Sequência
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