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1.
Clin Genet ; 95(6): 693-703, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30859559

RESUMO

Noonan syndrome (NS) is characterised by distinctive facial features, heart defects, variable degrees of intellectual disability and other phenotypic manifestations. Although the mode of inheritance is typically dominant, recent studies indicate LZTR1 may be associated with both dominant and recessive forms. Seeking to describe the phenotypic characteristics of LZTR1-associated NS, we searched for likely pathogenic variants using two approaches. First, scrutiny of exomes from 9624 patients recruited by the Deciphering Developmental Disorders (DDDs) study uncovered six dominantly-acting mutations (p.R97L; p.Y136C; p.Y136H, p.N145I, p.S244C; p.G248R) of which five arose de novo, and three patients with compound-heterozygous variants (p.R210*/p.V579M; p.R210*/p.D531N; c.1149+1G>T/p.R688C). One patient also had biallelic loss-of-function mutations in NEB, consistent with a composite phenotype. After removing this complex case, analysis of human phenotype ontology terms indicated significant phenotypic similarities (P = 0.0005), supporting a causal role for LZTR1. Second, targeted sequencing of eight unsolved NS-like cases identified biallelic LZTR1 variants in three further subjects (p.W469*/p.Y749C, p.W437*/c.-38T>A and p.A461D/p.I462T). Our study strengthens the association of LZTR1 with NS, with de novo mutations clustering around the KT1-4 domains. Although LZTR1 variants explain ~0.1% of cases across the DDD cohort, the gene is a relatively common cause of unsolved NS cases where recessive inheritance is suspected.

3.
Science ; 362(6419): 1161-1164, 2018 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-30409806

RESUMO

We estimated the genome-wide contribution of recessive coding variation in 6040 families from the Deciphering Developmental Disorders study. The proportion of cases attributable to recessive coding variants was 3.6% in patients of European ancestry, compared with 50% explained by de novo coding mutations. It was higher (31%) in patients with Pakistani ancestry, owing to elevated autozygosity. Half of this recessive burden is attributable to known genes. We identified two genes not previously associated with recessive developmental disorders, KDM5B and EIF3F, and functionally validated them with mouse and cellular models. Our results suggest that recessive coding variants account for a small fraction of currently undiagnosed nonconsanguineous individuals, and that the role of noncoding variants, incomplete penetrance, and polygenic mechanisms need further exploration.

4.
Am J Hum Genet ; 103(5): 786-793, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30343942

RESUMO

PCGF2 encodes the polycomb group ring finger 2 protein, a transcriptional repressor involved in cell proliferation, differentiation, and embryogenesis. PCGF2 is a component of the polycomb repressive complex 1 (PRC1), a multiprotein complex which controls gene silencing through histone modification and chromatin remodelling. We report the phenotypic characterization of 13 patients (11 unrelated individuals and a pair of monozygotic twins) with missense mutations in PCGF2. All the mutations affected the same highly conserved proline in PCGF2 and were de novo, excepting maternal mosaicism in one. The patients demonstrated a recognizable facial gestalt, intellectual disability, feeding problems, impaired growth, and a range of brain, cardiovascular, and skeletal abnormalities. Computer structural modeling suggests the substitutions alter an N-terminal loop of PCGF2 critical for histone biding. Mutant PCGF2 may have dominant-negative effects, sequestering PRC1 components into complexes that lack the ability to interact efficiently with histones. These findings demonstrate the important role of PCGF2 in human development and confirm that heterozygous substitutions of the Pro65 residue of PCGF2 cause a recognizable syndrome characterized by distinctive craniofacial, neurological, cardiovascular, and skeletal features.

5.
Eur J Hum Genet ; 2018 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-30310124

RESUMO

Technological advances have increased the availability of genomic data in research and the clinic. If, over time, interpretation of the significance of the data changes, or new information becomes available, the question arises as to whether recontacting the patient and/or family is indicated. The Public and Professional Policy Committee of the European Society of Human Genetics (ESHG), together with research groups from the UK and the Netherlands, developed recommendations on recontacting which, after public consultation, have been endorsed by ESHG Board. In clinical genetics, recontacting for updating patients with new, clinically significant information related to their diagnosis or previous genetic testing may be justifiable and, where possible, desirable. Consensus about the type of information that should trigger recontacting converges around its clinical and personal utility. The organization of recontacting procedures and policies in current health care systems is challenging. It should be sustainable, commensurate with previously obtained consent, and a shared responsibility between healthcare providers, laboratories, patients, and other stakeholders. Optimal use of the limited clinical resources currently available is needed. Allocation of dedicated resources for recontacting should be considered. Finally, there is a need for more evidence, including economic and utility of information for people, to inform which strategies provide the most cost-effective use of healthcare resources for recontacting.

6.
Am J Hum Genet ; 103(1): 100-114, 2018 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-29979980

RESUMO

The tRNA synthetases catalyze the first step of protein synthesis and have increasingly been studied for their nuclear and extra-cellular ex-translational activities. Human genetic conditions such as Charcot-Marie-Tooth have been attributed to dominant gain-of-function mutations in some tRNA synthetases. Unlike dominantly inherited gain-of-function mutations, recessive loss-of-function mutations can potentially elucidate ex-translational activities. We present here five individuals from four families with a multi-system disease associated with bi-allelic mutations in FARSB that encodes the beta chain of the alpha2beta2 phenylalanine-tRNA synthetase (FARS). Collectively, the mutant alleles encompass a 5'-splice junction non-coding variant (SJV) and six missense variants, one of which is shared by unrelated individuals. The clinical condition is characterized by interstitial lung disease, cerebral aneurysms and brain calcifications, and cirrhosis. For the SJV, we confirmed exon skipping leading to a frameshift associated with noncatalytic activity. While the bi-allelic combination of the SJV with a p.Arg305Gln missense mutation in two individuals led to severe disease, cells from neither the asymptomatic heterozygous carriers nor the compound heterozygous affected individual had any defect in protein synthesis. These results support a disease mechanism independent of tRNA synthetase activities in protein translation and suggest that this FARS activity is essential for normal function in multiple organs.

7.
Ann Neurol ; 83(6): 1198-1204, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29740868

RESUMO

Variants in several potassium channel genes have been found in developmental and epileptic encephalopathies (DEE). We report on 2 females with de novo variants in KCNT2 with West syndrome followed by Lennox-Gastaut syndrome or with DEE with migrating focal seizures. After in vitro analysis suggested quinidine-responsive gain-of-function effects, we treated 1 of the girls with quinidine add-on therapy and achieved marked clinical improvements. This suggests that the new spectrum of KCNT2-related disorders do not only share similar phenotypic and in vitro functional and pharmacological features with previously known KCNT1-related disorders, but also represents a further example for possible precision medicine approaches. Ann Neurol 2018;83:1198-1204.

8.
Eur J Med Genet ; 2018 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-29698805

RESUMO

In the last 3 years de novo sequence variants in the ARID2 (AT-rich interaction domain 2) gene, a subunit of the SWI/SNF complex, have been linked to intellectual disabilities in 3 case reports including one which describes frameshift mutations in ARID2 in 2 patients with features resembling Coffin-Siris syndrome. Coffin-Siris syndrome (CSS) is a rare congenital syndrome characterized by intellectual deficit, coarse facial features and hypoplastic or absent fifth fingernails and/or toenails among other features. Mutations in a number of different genes encoding SWI/SNF chromatin remodelling complex proteins have been described but the underlying molecular cause remains unknown in approximately 40% of patients with CSS. Here we describe 7 unrelated individuals, 2 with deletions of the ARID2 region and 5 with de novo truncating mutations in the ARID2 gene. Similarities to CSS are evident. Although hypertrichosis and hypoplasia of the fifth finger nail and distal phalanx do not appear to be common in these patients, toenail hypoplasia and the presence of Wormian bones might support the involvement of ARID2.

9.
Eur J Hum Genet ; 26(7): 946-954, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29681620

RESUMO

Advances in genomic medicine are improving diagnosis and treatment of some health conditions, and the question of whether former patients should be recontacted is therefore timely. The issue of recontacting is becoming more important with increased integration of genomics in 'mainstream' medicine. Empirical evidence is needed to advance the discussion over whether and how recontacting should be implemented. We administered a web-based survey to genetic services in European countries to collect information about existing infrastructures and practices relevant to recontacting patients. The majority of the centres stated they had recontacted patients to update them about new significant information; however, there were no standardised practices or systems in place. There was also a multiplicity of understandings of the term 'recontacting', which respondents conflated with routine follow-up programmes, or even with post-test counselling. Participants thought that recontacting systems should be implemented to provide the best service to the patients and families. Nevertheless, many barriers to implementation were mentioned. These included: lack of resources and infrastructure, concerns about potential negative psychological consequences of recontacting, unclear operational definitions of recontacting, policies that prevent healthcare professionals from recontacting, and difficulties in locating patients after their last contact. These barriers are also intensified by the highly variable development (and establishment) of the specialties of medical genetics and genetic counselling across different European countries. Future recommendations about recontacting need to consider these barriers. It is also important to reach an 'operational definition' that can be useful in different countries.

10.
Am J Med Genet A ; 176(1): 253-256, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29159998

RESUMO

Scoliosis represents the most common musculoskeletal disorder in children and affects approximately 3% of the world population. Scoliosis is separated into two major phenotypic classifications: congenital and idiopathic. Idiopathic scoliosis is defined as a curvature of the spine of 10° or greater visualized on plane radiograph and does not have associated vertebral malformations (VM). "Congenital" scoliosis (CS) due to malformations in vertebrae is frequently associated with other birth defects. Recently, significant advances have been made in understanding the genetic basis of both conditions. There is evidence that both conditions are etiologically related. A 2-day conference entitled "Genomic Approaches to Understanding and Treating Scoliosis" was held at Scottish Rite Hospital for Children in Dallas, Texas, to synergize research in this field. This first combined, multidisciplinary conference featured international scoliosis researchers in basic and clinical sciences. A major outcome of the conference advancing scoliosis research was the proposal and subsequent vote in favor of merging the International Consortium for Vertebral Anomalies and Scoliosis (ICVAS) and International Consortium for Scoliosis Genetics (ICSG) into a single entity called International Consortium for Spinal Genetics, Development, and Disease (ICSGDD). The ICSGDD is proposed to meet annually as a forum to synergize multidisciplinary spine deformity research.


Assuntos
Escoliose/diagnóstico , Escoliose/genética , Humanos
11.
Prenat Diagn ; 38(1): 33-43, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29096039

RESUMO

OBJECTIVE: Rare genetic disorders resulting in prenatal or neonatal death are genetically heterogeneous, but testing is often limited by the availability of fetal DNA, leaving couples without a potential prenatal test for future pregnancies. We describe our novel strategy of exome sequencing parental DNA samples to diagnose recessive monogenic disorders in an audit of the first 50 couples referred. METHOD: Exome sequencing was carried out in a consecutive series of 50 couples who had 1 or more pregnancies affected with a lethal or prenatal-onset disorder. In all cases, there was insufficient DNA for exome sequencing of the affected fetus. Heterozygous rare variants (MAF < 0.001) in the same gene in both parents were selected for analysis. Likely, disease-causing variants were tested in fetal DNA to confirm co-segregation. RESULTS: Parental exome analysis identified heterozygous pathogenic (or likely pathogenic) variants in 24 different genes in 26/50 couples (52%). Where 2 or more fetuses were affected, a genetic diagnosis was obtained in 18/29 cases (62%). In most cases, the clinical features were typical of the disorder, but in others, they result from a hypomorphic variant or represent the most severe form of a variable phenotypic spectrum. CONCLUSION: We conclude that exome sequencing of parental samples is a powerful strategy with high clinical utility for the genetic diagnosis of lethal or prenatal-onset recessive disorders. © 2017 The Authors Prenatal Diagnosis published by John Wiley & Sons Ltd.


Assuntos
Anormalidades Congênitas/genética , Doenças Genéticas Inatas/diagnóstico , Pais , Diagnóstico Pré-Natal/métodos , Sequenciamento Completo do Exoma , Feminino , Genes Recessivos , Humanos , Masculino , Gravidez
12.
Eur J Hum Genet ; 25(10): 1106-1112, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28766552

RESUMO

This paper explores the views and expectations of patients concerning recontacting in clinical practice. It is based on 41 semi-structured interviews conducted in the United Kingdom. The sample comprised patients or parents of patients: without a diagnosis; recently offered a test for a condition or carrier risk; with a rare condition; with a variant of unknown significance - some of whom had been recontacted. Participants were recruited both via the National Health Service (NHS) and through online, condition-specific support groups. Most respondents viewed recontacting as desirable, however there were different opinions and expectations about what type of new information should trigger recontacting. An awareness of the potential psychological impact of receiving new information led some to suggest that recontacting should be planned, and tailored to the nature of the new information and the specific situation of patients and families. The lack of clarity about lines of responsibility for recontacting and perceptions of resource constraints in the NHS tended to mitigate respondents' favourable positions towards recontacting and their preferences. Some respondents argued that recontacting could have a preventative value and reduce the cost of healthcare. Others challenged the idea that resources should be used to implement formalised recontacting systems - via arguments that there are 'more pressing' public health priorities, and for the need for healthcare services to offer care to new patients.


Assuntos
Dever de Recontatar , Doenças Genéticas Inatas/psicologia , Conhecimentos, Atitudes e Prática em Saúde , Relações Médico-Paciente , Feminino , Doenças Genéticas Inatas/diagnóstico , Heterozigoto , Humanos , Masculino , Inquéritos e Questionários , Reino Unido
13.
J Am Soc Nephrol ; 28(8): 2529-2539, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28373276

RESUMO

Hyperinsulinemic hypoglycemia (HI) and congenital polycystic kidney disease (PKD) are rare, genetically heterogeneous disorders. The co-occurrence of these disorders (HIPKD) in 17 children from 11 unrelated families suggested an unrecognized genetic disorder. Whole-genome linkage analysis in five informative families identified a single significant locus on chromosome 16p13.2 (logarithm of odds score 6.5). Sequencing of the coding regions of all linked genes failed to identify biallelic mutations. Instead, we found in all patients a promoter mutation (c.-167G>T) in the phosphomannomutase 2 gene (PMM2), either homozygous or in trans with PMM2 coding mutations. PMM2 encodes a key enzyme in N-glycosylation. Abnormal glycosylation has been associated with PKD, and we found that deglycosylation in cultured pancreatic ß cells altered insulin secretion. Recessive coding mutations in PMM2 cause congenital disorder of glycosylation type 1a (CDG1A), a devastating multisystem disorder with prominent neurologic involvement. Yet our patients did not exhibit the typical clinical or diagnostic features of CDG1A. In vitro, the PMM2 promoter mutation associated with decreased transcriptional activity in patient kidney cells and impaired binding of the transcription factor ZNF143. In silico analysis suggested an important role of ZNF143 for the formation of a chromatin loop including PMM2 We propose that the PMM2 promoter mutation alters tissue-specific chromatin loop formation, with consequent organ-specific deficiency of PMM2 leading to the restricted phenotype of HIPKD. Our findings extend the spectrum of genetic causes for both HI and PKD and provide insights into gene regulation and PMM2 pleiotropy.


Assuntos
Hiperinsulinismo Congênito/complicações , Hiperinsulinismo Congênito/genética , Mutação , Fosfotransferases (Fosfomutases)/genética , Doenças Renais Policísticas/complicações , Doenças Renais Policísticas/genética , Regiões Promotoras Genéticas/genética , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino
16.
Eur J Hum Genet ; 25(3): 275-279, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28051074

RESUMO

This article explores the views and experiences of healthcare professionals and clinical scientists in genetics about the existence of a duty and/or responsibility to recontact former patients when the genetic information relevant to their health, or that of family members, changes in a potentially important manner. It is based on N=30 semi-structured interviews guided by vignettes of recontacting scenarios. The sample included healthcare professionals in the United Kingdom from different medical specialties (clinical genetics, other 'mainstream' specialties now offering genetic testing), and scientists from regional genetics laboratories. While viewing recontacting as desirable under certain circumstances, most respondents expressed concerns about its feasibility within the current constraints of the National Health Service (NHS). The main barriers identified were insufficient resources (time, staff, and suitable IT infrastructures) and lack of clarity about role boundaries and responsibilities. All of these are further complicated by genetic testing being increasingly offered by mainstream specialties. Reaching a consensus about roles and responsibilities of clinical specialties with regard to recontacting former patients in the light of evolving genetic information, and about what resources and infrastructures would be needed, was generally seen as a pre-requisite to developing guidelines about recontact.


Assuntos
Atitude do Pessoal de Saúde , Dever de Recontatar , Aconselhamento Genético/ética , Testes Genéticos/ética , Aconselhamento Genético/psicologia , Aconselhamento Genético/normas , Testes Genéticos/normas , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Reino Unido
17.
Genet Med ; 18(9): 876-81, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-26890453

RESUMO

PURPOSE: To ascertain whether and how recontacting occurs in the United Kingdom. METHOD: A Web-based survey was administered online between October 2014 and July 2015. A link to the survey was circulated via an e-mail invitation to the clinical leads of the United Kingdom's 23 clinical genetics services, with follow-up with senior clinical genetics staff. RESULTS: The majority of UK services reported that they recontact patients and their family members. However, recontacting generally occurs in an ad hoc fashion when an unplanned event causes clinicians to review a file (a "trigger"). There are no standardized recontacting practices in the United Kingdom. More than half of the services were unsure whether formalized recontacting systems should be implemented. Some suggested greater patient involvement in the process of recontacting. CONCLUSION: This research suggests that a thorough evaluation of the efficacy and sustainability of potential recontacting systems within the National Health Service would be necessary before deciding whether and how to implement such a service or to create guidelines on best-practice models.Genet Med 18 9, 876-881.


Assuntos
Dever de Recontatar , Genética Médica , Serviços de Saúde , Humanos , Inquéritos e Questionários , Reino Unido , Recursos Humanos
18.
Cell Mol Gastroenterol Hepatol ; 2(5): 542-543, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28174734
20.
J Med Genet ; 51(12): 806-13, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25342064

RESUMO

BACKGROUND: De novo mutations are emerging as an important cause of neurocognitive impairment, and whole exome sequencing of case-parent trios is a powerful way of detecting them. Here, we report the findings in four such trios. METHODS: The Deciphering Developmental Disorders study is using whole exome sequencing in family trios to investigate children with severe, sporadic, undiagnosed developmental delay. Three of our patients were ascertained from the first 1133 children to have been investigated through this large-scale study. Case 4 was a phenotypically isolated case recruited into an undiagnosed rare disorders sequencing study. RESULTS: Protein-altering de novo mutations in PURA were identified in four subjects. They include two different frameshifts, one inframe deletion and one missense mutation. PURA encodes Pur-α, a highly conserved multifunctional protein that has an important role in normal postnatal brain development in animal models. The associated human phenotype of de novo heterozygous mutations in this gene is variable, but moderate to severe neurodevelopmental delay and learning disability are common to all. Neonatal hypotonia, early feeding difficulties and seizures, or 'seizure-like' movements, were also common. Additionally, it is suspected that anterior pituitary dysregulation may be within the spectrum of this disorder. Psychomotor developmental outcomes appear variable between patients, and we propose a possible genotype-phenotype correlation, with disruption of Pur repeat III resulting in a more severe phenotype. CONCLUSIONS: These findings provide definitive evidence for the role of PURA in causing a variable syndrome of neurodevelopmental delay, learning disability, neonatal hypotonia, feeding difficulties, abnormal movements and epilepsy in humans, and help clarify the role of PURA in the previously described 5q31.3 microdeletion phenotype.


Assuntos
Proteínas de Ligação a DNA/genética , Deficiências do Desenvolvimento/genética , Transtornos de Aprendizagem/genética , Mutação , Fatores de Transcrição/genética , Sequência de Aminoácidos , Substituição de Aminoácidos , Encéfalo/patologia , Criança , Pré-Escolar , Proteínas de Ligação a DNA/química , Deficiências do Desenvolvimento/diagnóstico , Exoma , Facies , Feminino , Ordem dos Genes , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Transtornos de Aprendizagem/diagnóstico , Imagem por Ressonância Magnética , Modelos Moleculares , Fenótipo , Conformação Proteica , Fatores de Transcrição/química
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