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1.
Hum Mutat ; 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31646703

RESUMO

We recently described a new neurodevelopmental syndrome (TAF1/MRXS33 intellectual disability syndrome) (MIM# 300966) caused by pathogenic variants involving the X-linked gene TAF1, which participates in RNA polymerase II transcription. The initial study reported eleven families, and the syndrome was defined as presenting early in life with hypotonia, facial dysmorphia, and developmental delay that evolved into intellectual disability (ID) and/or autism spectrum disorder (ASD). We have now identified an additional 27 families through a genotype-first approach. Familial segregation analysis, clinical phenotyping, and bioinformatics were capitalized on to assess potential variant pathogenicity, and molecular modelling was performed for those variants falling within structurally characterized domains of TAF1. A novel phenotypic clustering approach was also applied, in which the phenotypes of affected individuals were classified using 51 standardized Human Phenotype Ontology (HPO) terms. Phenotypes associated with TAF1 variants show considerable pleiotropy and clinical variability, but prominent among previously unreported effects were brain morphological abnormalities, seizures, hearing loss, and heart malformations. Our allelic series broadens the phenotypic spectrum of TAF1/MRXS33 intellectual disability syndrome and the range of TAF1 molecular defects in humans. It also illustrates the challenges for determining the pathogenicity of inherited missense variants, particularly for genes mapping to chromosome X. This article is protected by copyright. All rights reserved.

2.
Neuromuscul Disord ; 29(6): 456-467, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31130376

RESUMO

Myopathies due to recessive MYH7 mutations are exceedingly rare, reported in only two families to date. We describe three patients from two families (from Australia and the UK) with a myopathy caused by recessive mutations in MYH7. The Australian family was homozygous for a c.5134C > T, p.Arg1712Trp mutation, whilst the UK patient was compound heterozygous for a truncating (c.4699C > T; p.Gln1567*) and a missense variant (c.4664A > G; p.Glu1555Gly). All three patients shared key clinical features, including infancy/childhood onset, pronounced axial/proximal weakness, spinal rigidity, severe scoliosis, and normal cardiac function. There was progressive respiratory impairment necessitating non-invasive ventilation despite preserved ambulation, a combination of features often seen in SEPN1- or NEB-related myopathies. On biopsy, the Australian proband showed classical myosin storage myopathy features, while the UK patient showed multi-minicore like areas. To establish pathogenicity of the Arg1712Trp mutation, we expressed mutant MYH7 protein in COS-7 cells, observing abnormal mutant myosin aggregation compared to wild-type. We describe skinned myofiber studies of patient muscle and hypertrophy of type II myofibers, which may be a compensatory mechanism. In summary, we have expanded the phenotype of ultra-rare recessive MYH7 disease, and provide novel insights into associated changes in muscle physiology.

3.
J Med Genet ; 55(12): 837-846, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30323018

RESUMO

BACKGROUND: Wiedemann-Rautenstrauch syndrome (WRS) is a form of segmental progeria presenting neonatally, characterised by growth retardation, sparse scalp hair, generalised lipodystrophy with characteristic local fatty tissue accumulations and unusual face. We aimed to understand its molecular cause. METHODS: We performed exome sequencing in two families, targeted sequencing in 10 other families and performed in silico modelling studies and transcript processing analyses to explore the structural and functional consequences of the identified variants. RESULTS: Biallelic POLR3A variants were identified in eight affected individuals and monoallelic variants of the same gene in four other individuals. In the latter, lack of genetic material precluded further analyses. Multiple variants were found to affect POLR3A transcript processing and were mostly located in deep intronic regions, making clinical suspicion fundamental to detection. While biallelic POLR3A variants have been previously reported in 4H syndrome and adolescent-onset progressive spastic ataxia, recurrent haplotypes specifically occurring in individuals with WRS were detected. All WRS-associated POLR3A amino acid changes were predicted to perturb substantially POLR3A structure/function. CONCLUSION: Biallelic mutations in POLR3A, which encodes for the largest subunit of the DNA-dependent RNA polymerase III, underlie WRS. No isolated functional sites in POLR3A explain the phenotype variability in POLR3A-related disorders. We suggest that specific combinations of compound heterozygous variants must be present to cause the WRS phenotype. Our findings expand the molecular mechanisms contributing to progeroid disorders.

6.
J Bone Miner Res ; 33(7): 1260-1271, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29669177

RESUMO

Osteogenesis imperfecta (OI) is a genetic bone disorder characterized by fractures, low bone mass, and skeletal fragility. It most commonly arises from dominantly inherited mutations in the genes COL1A1 and COL1A2 that encode the chains of type I collagen. A number of recent reports have suggested that mutations affecting the carboxyl-terminal propeptide cleavage site in the products of either COL1A1 or COL1A2 give rise to a form of OI characterized by unusually dense bones. We have assembled clinical, biochemical, and molecular data from 29 individuals from 8 families with 7 different mutations affecting the C-propeptide cleavage site. The phenotype was generally mild: The median height was ∼33th centile. Eighty percent of subjects had their first fracture by the age of 10 years, and one-third had a femoral or tibial fracture by the age of 25 years. Fractures continued into adulthood, though rates varied considerably. Healing was normal and rarely resulted in long bone deformity. One-third of subjects older than 15 years had scoliosis. The teeth and hearing were normal in most, and blue sclerae were not observed. Other features noted included fibro-osseous dysplasia of the mandible and Achilles tendon calcification. The mean spinal bone mineral density Z-score was +2.9 (SD 2.1) compared with -2.2 (0.7) in subjects with COL1A1 haploinsufficiency mutations. Bone mineral density distribution, assessed by quantitative backscattered electron imaging in bone showed higher levels of mineralization than found in any other disorder. Bone histology showed high trabecular volume and increased cortical thickness, with hyperosteoidosis and delayed mineralization. In vitro studies with cultured skin fibroblasts suggested that these mutations interfere with processing of the chain in which the sequence alteration occurs, but the C-propeptide is eventually cleaved (and detectable in blood), suggesting there are alternative sites of cleavage. The precise mechanism of the bony pathology is not yet clear. © 2018 American Society for Bone and Mineral Research.

7.
J Clin Endocrinol Metab ; 103(5): 1834-1841, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29409041

RESUMO

Context: Bardet-Biedl syndrome (BBS) is a rare autosomal recessive disorder in which previous reports have described obesity and a metabolic syndrome. Objective: We describe the endocrine and metabolic characteristics of a large BBS population compared with matched control subjects. Design: We performed a case-control study. Setting: This study was performed at a hospital clinic. Patients: Study patients had a clinical or genetic diagnosis of BBS. Main Outcome Measurements: Our study determined the prevalence of a metabolic syndrome in our cohort. Results: A total of 152 subjects were studied. Eighty-four (55.3%) were male. Mean (± standard deviation) age was 33.2 ± 1.0 years. Compared with age-, sex-, and body mass index-matched control subjects, fasting glucose and insulin levels were significantly higher in subjects with BBS (glucose: BBS, 5.2 ± 1.2 mmol/L vs control, 4.9 ± 0.9 mmol/L, P = 0.04; insulin: BBS, 24.2 ± 17.0 pmol/L vs control, 14.2 ± 14.8 pmol/L, P < 0.001). Serum triglycerides were significantly higher in subjects with BBS (2.0 ± 1.2 mmol/L) compared with control subjects (1.3 ± 0.8 mmol/L; P < 0.001), but total cholesterol, high-density lipoprotein, and low-density lipoprotein were similar in both groups. Systolic blood pressure was higher in the BBS group (BBS, 135 ± 18 mm Hg vs control subjects, 129 ± 16 mm Hg; P = 0.02). Alanine transaminase was raised in 34 (26.8%) subjects with BBS, compared with five (8.9%) control subjects (P = 0.01). The rate of metabolic syndrome, determined using International Diabetes Federation criteria, was significantly higher in the BBS group (54.3%) compared with control subjects (26% P < 0.001). Twenty-six (19.5%) of male subjects with BBS were hypogonadal (serum testosterone, 9.9 ± 5.3 mmol/L), but significant pituitary abnormalities were uncommon. Subclinical hypothyroidism was present in 24 of 125 (19.4%) patients with BBS, compared with 3 of 65 (4.6%) control subjects (P = 0.01). Conclusions: Insulin resistance and the metabolic syndrome are increased in adult patients with BBS compared with matched control subjects. Increased subclinical hypothyroidism in the BBS cohort needs further investigation.

8.
Epilepsy Res ; 140: 166-170, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29367179

RESUMO

Bainbridge-Ropers syndrome is a genetic syndrome caused by heterozygous loss-of-function pathogenic variants in ASXL3, which encodes a protein involved in transcriptional regulation. Affected individuals have multiple abnormalities including developmental impairment, hypotonia and characteristic facial features. Seizures are reported in approximately a third of cases; however, the epileptology has not been thoroughly studied. We identified three patients with pathogenic ASXL3 variants and seizures at Austin Health and in the DECIPHER database. These three patients had novel de novo ASXL3 pathogenic variants, two with truncation variants and one with a splice site variant. All three had childhood-onset generalized epilepsy with generalized tonic-clonic seizures, with one also having atypical absence seizures. We also reviewed available clinical data on five published patients with Bainbridge-Ropers syndrome and seizures. Of the five previously published patients, three also had generalized tonic-clonic seizures, one of whom also had possible absence seizures; a fourth patient had absence seizures and possible focal seizures. EEG typically showed features consistent with generalized epilepsy including generalized spike-wave, photoparoxysmal response, and occipital intermittent rhythmic epileptiform activity. Bainbridge-Ropers syndrome is associated with childhood-onset generalized epilepsy with generalized tonic-clonic seizures and/or atypical absence seizures.

9.
Genet Med ; 20(10): 1236-1245, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29323665

RESUMO

PURPOSE: We delineate the clinical spectrum and describe the histology in arterial tortuosity syndrome (ATS), a rare connective tissue disorder characterized by tortuosity of the large and medium-sized arteries, caused by mutations in SLC2A10. METHODS: We retrospectively characterized 40 novel ATS families (50 patients) and reviewed the 52 previously reported patients. We performed histology and electron microscopy (EM) on skin and vascular biopsies and evaluated TGF-ß signaling with immunohistochemistry for pSMAD2 and CTGF. RESULTS: Stenoses, tortuosity, and aneurysm formation are widespread occurrences. Severe but rare vascular complications include early and aggressive aortic root aneurysms, neonatal intracranial bleeding, ischemic stroke, and gastric perforation. Thus far, no reports unequivocally document vascular dissections or ruptures. Of note, diaphragmatic hernia and infant respiratory distress syndrome (IRDS) are frequently observed. Skin and vascular biopsies show fragmented elastic fibers (EF) and increased collagen deposition. EM of skin EF shows a fragmented elastin core and a peripheral mantle of microfibrils of random directionality. Skin and end-stage diseased vascular tissue do not indicate increased TGF-ß signaling. CONCLUSION: Our findings warrant attention for IRDS and diaphragmatic hernia, close monitoring of the aortic root early in life, and extensive vascular imaging afterwards. EM on skin biopsies shows disease-specific abnormalities.

10.
Am J Hum Genet ; 101(3): 466-477, 2017 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-28886345

RESUMO

RAC1 is a widely studied Rho GTPase, a class of molecules that modulate numerous cellular functions essential for normal development. RAC1 is highly conserved across species and is under strict mutational constraint. We report seven individuals with distinct de novo missense RAC1 mutations and varying degrees of developmental delay, brain malformations, and additional phenotypes. Four individuals, each harboring one of c.53G>A (p.Cys18Tyr), c.116A>G (p.Asn39Ser), c.218C>T (p.Pro73Leu), and c.470G>A (p.Cys157Tyr) variants, were microcephalic, with head circumferences between -2.5 to -5 SD. In contrast, two individuals with c.151G>A (p.Val51Met) and c.151G>C (p.Val51Leu) alleles were macrocephalic with head circumferences of +4.16 and +4.5 SD. One individual harboring a c.190T>G (p.Tyr64Asp) allele had head circumference in the normal range. Collectively, we observed an extraordinary spread of ∼10 SD of head circumferences orchestrated by distinct mutations in the same gene. In silico modeling, mouse fibroblasts spreading assays, and in vivo overexpression assays using zebrafish as a surrogate model demonstrated that the p.Cys18Tyr and p.Asn39Ser RAC1 variants function as dominant-negative alleles and result in microcephaly, reduced neuronal proliferation, and cerebellar abnormalities in vivo. Conversely, the p.Tyr64Asp substitution is constitutively active. The remaining mutations are probably weakly dominant negative or their effects are context dependent. These findings highlight the importance of RAC1 in neuronal development. Along with TRIO and HACE1, a sub-category of rare developmental disorders is emerging with RAC1 as the central player. We show that ultra-rare disorders caused by private, non-recurrent missense mutations that result in varying phenotypes are challenging to dissect, but can be delineated through focused international collaboration.


Assuntos
Encefalopatias/genética , Deficiências do Desenvolvimento/genética , Microcefalia/genética , Mutação de Sentido Incorreto , Proteínas rac1 de Ligação ao GTP/genética , Adolescente , Sequência de Aminoácidos , Animais , Encefalopatias/patologia , Criança , Pré-Escolar , Deficiências do Desenvolvimento/patologia , Embrião não Mamífero/metabolismo , Embrião não Mamífero/patologia , Feminino , Humanos , Lactente , Masculino , Camundongos , Microcefalia/patologia , Linhagem , Fenótipo , Peixe-Zebra/genética , Peixe-Zebra/crescimento & desenvolvimento
11.
Am J Med Genet A ; 173(9): 2522-2527, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28748650

RESUMO

Vici syndrome is one of the most extensive inherited human multisystem disorders and due to recessive mutations in EPG5 encoding a key autophagy regulator with a crucial role in autophagosome-lysosome fusion. The condition presents usually early in life, with features of severe global developmental delay, profound failure to thrive, (acquired) microcephaly, callosal agenesis, cataracts, cardiomyopathy, hypopigmentation, and combined immunodeficiency. Clinical course is variable but usually progressive and associated with high mortality. Here, we present a fetus, offspring of consanguineous parents, in whom callosal agenesis and other developmental brain abnormalities were detected on fetal ultrasound scan (US) and subsequent MRI scan in the second trimester. Postmortem examination performed after medically indicated termination of pregnancy confirmed CNS abnormalities and provided additional evidence for skin hypopigmentation, nascent cataracts, and hypertrophic cardiomyopathy. Genetic testing prompted by a suggestive combination of features revealed a homozygous EPG5 mutation (c.5870-1G>A) predicted to cause aberrant splicing of the EPG5 transcript. Our findings expand the phenotypical spectrum of EPG5-related Vici syndrome and suggest that this severe condition may already present in utero. While callosal agenesis is not an uncommon finding in fetal medicine, additional presence of hypopigmentation, cataracts and cardiomyopathy is rare and should prompt EPG5 testing.


Assuntos
Agenesia do Corpo Caloso/genética , Síndrome de Aicardi/genética , Catarata/genética , Síndromes de Imunodeficiência/genética , Proteínas/genética , Idade de Início , Agenesia do Corpo Caloso/diagnóstico por imagem , Agenesia do Corpo Caloso/fisiopatologia , Síndrome de Aicardi/fisiopatologia , Autopsia , Catarata/diagnóstico por imagem , Catarata/fisiopatologia , Consanguinidade , Feto/diagnóstico por imagem , Feto/fisiopatologia , Humanos , Hipopigmentação/genética , Hipopigmentação/fisiopatologia , Síndromes de Imunodeficiência/diagnóstico por imagem , Síndromes de Imunodeficiência/fisiopatologia , Imagem por Ressonância Magnética , Mutação , Fenótipo , Diagnóstico Pré-Natal
12.
Metabolism ; 71: 213-225, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28521875

RESUMO

BACKGROUND: Mandibular hypoplasia, deafness, progeroid features, and lipodystrophy syndrome (MDPL) is an autosomal dominant systemic disorder characterized by prominent loss of subcutaneous fat, a characteristic facial appearance and metabolic abnormalities. This syndrome is caused by heterozygous de novo mutations in the POLD1 gene. To date, 19 patients with MDPL have been reported in the literature and among them 14 patients have been characterized at the molecular level. Twelve unrelated patients carried a recurrent in-frame deletion of a single codon (p.Ser605del) and two other patients carried a novel heterozygous mutation in exon 13 (p.Arg507Cys). Additionally and interestingly, germline mutations of the same gene have been involved in familial polyposis and colorectal cancer (CRC) predisposition. PATIENTS AND METHODS: We describe a male and a female patient with MDPL respectively affected with mild and severe phenotypes. Both of them showed mandibular hypoplasia, a beaked nose with bird-like facies, prominent eyes, a small mouth, growth retardation, muscle and skin atrophy, but the female patient showed such a severe and early phenotype that a first working diagnosis of Hutchinson-Gilford Progeria was made. The exploration was performed by direct sequencing of POLD1 gene exon 15 in the male patient with a classical MDPL phenotype and by whole exome sequencing in the female patient and her unaffected parents. RESULTS: Exome sequencing identified in the latter patient a de novo heterozygous undescribed mutation in the POLD1 gene (NM_002691.3: c.3209T>A), predicted to cause the missense change p.Ile1070Asn in the ZnF2 (Zinc Finger 2) domain of the protein. This mutation was not reported in the 1000 Genome Project, dbSNP and Exome sequencing databases. Furthermore, the Isoleucine1070 residue of POLD1 is highly conserved among various species, suggesting that this substitution may cause a major impairment of POLD1 activity. For the second patient, affected with a typical MDPL phenotype, direct sequencing of POLD1 exon 15 revealed the recurrent in-frame deletion (c.1812_1814del, p.S605del). CONCLUSION: Our work highlights that mutations in different POLD1 domains can lead to phenotypic variability, ranging from dominantly inherited cancer predisposition syndromes, to mild MDPL phenotypes without lifespan reduction, to very severe MDPL syndromes with major premature aging features. These results also suggest that POLD1 gene testing should be considered in patients presenting with severe progeroid features.


Assuntos
DNA Polimerase III/genética , Surdez/genética , Exoma/genética , Lipodistrofia/genética , Mutação , Progéria/genética , Idade de Início , Criança , Surdez/patologia , Surdez/psicologia , Éxons/genética , Feminino , Deleção de Genes , Humanos , Lipodistrofia/patologia , Lipodistrofia/psicologia , Masculino , Fenótipo , Progéria/patologia , Progéria/psicologia , Análise de Sequência de Proteína , Síndrome , Adulto Jovem
13.
Am J Med Genet A ; 2017 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-28447407

RESUMO

Wiedemann-Rautenstrauch syndrome (WRS) is a neonatal progeroid disorder characterized by growth retardation, lipodystrophy, a distinctive face, and dental anomalies. Patients reported to date demonstrate a remarkable variability in phenotype, which hampers diagnostics. We performed a literature search, and analyzed 51 reported patients, using the originally reported patients as "gold standard." In 15 patients sufficient information and photographic evidence was available to confirm the clinical diagnosis. In 12 patients the diagnosis was suggestive but lack of data prevented a definite diagnosis, and in 24 patients an alternative diagnosis was likely. Core manifestations of the syndrome are marked pre-natal and severe post-natal growth retardation, an unusual face (triangular shape, sparse hair, small mouth, pointed chin), dental anomalies (natal teeth; hypodontia), generalized lipodystrophy with localized fat masses, and-in some cases-progressive ataxia and tremor. It has been suggested that the syndrome might be caused by biallelic variants in POLR3A, identified by exome sequencing in a single patient only. Therefore, we compared the WRS phenotype with characteristics of conditions known to be caused by autosomal recessively inherited POLR3A mutations. There are major differences but there are also similarities in phenotype, which sustain the suggestion that the syndrome can be caused by disturbed POLR3A functioning.

14.
Genet Med ; 19(8): 900-908, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28151491

RESUMO

PURPOSE: To characterize features associated with de novo mutations affecting SATB2 function in individuals ascertained on the basis of intellectual disability. METHODS: Twenty previously unreported individuals with 19 different SATB2 mutations (11 loss-of-function and 8 missense variants) were studied. Fibroblasts were used to measure mutant protein production. Subcellular localization and mobility of wild-type and mutant SATB2 were assessed using fluorescently tagged protein. RESULTS: Recurrent clinical features included neurodevelopmental impairment (19/19), absent/near absent speech (16/19), normal somatic growth (17/19), cleft palate (9/19), drooling (12/19), and dental anomalies (8/19). Six of eight missense variants clustered in the first CUT domain. Sibling recurrence due to gonadal mosaicism was seen in one family. A nonsense mutation in the last exon resulted in production of a truncated protein retaining all three DNA-binding domains. SATB2 nuclear mobility was mutation-dependent; p.Arg389Cys in CUT1 increased mobility and both p.Gly515Ser in CUT2 and p.Gln566Lys between CUT2 and HOX reduced mobility. The clinical features in individuals with missense variants were indistinguishable from those with loss of function. CONCLUSION: SATB2 haploinsufficiency is a common cause of syndromic intellectual disability. When mutant SATB2 protein is produced, the protein appears functionally inactive with a disrupted pattern of chromatin or matrix association.Genet Med advance online publication 02 February 2017.


Assuntos
Deficiência Intelectual/genética , Mutação com Perda de Função , Proteínas de Ligação à Região de Interação com a Matriz/genética , Mutação de Sentido Incorreto , Fatores de Transcrição/genética , Linhagem Celular , Estudos de Coortes , Estudos de Associação Genética , Haploinsuficiência/genética , Células HeLa , Humanos , Deficiência Intelectual/fisiopatologia , Proteínas de Ligação à Região de Interação com a Matriz/fisiologia , Ligação Proteica/genética , Fatores de Transcrição/fisiologia , Sequenciamento Completo do Genoma
15.
J Am Soc Nephrol ; 28(3): 963-970, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27659767

RESUMO

Bardet-Biedl syndrome is a rare autosomal recessive, multisystem disease characterized by retinal dystrophy, renal malformation, obesity, intellectual disability, polydactyly, and hypogonadism. Nineteen disease-causing genes (BBS1-19) have been identified, of which mutations in BBS1 are most common in North America and Europe. A hallmark of the disease, renal malformation is heterogeneous and is a cause of morbidity and mortality through the development of CKD. We studied the prevalence and severity of CKD in 350 patients with Bardet-Biedl syndrome-related renal disease attending the United Kingdom national Bardet-Biedl syndrome clinics to further elucidate the phenotype and identify risk indicators of CKD. Overall, 31% of children and 42% of adults had CKD; 6% of children and 8% of adults had stage 4-5 CKD. In children, renal disease was often detected within the first year of life. Analysis of the most commonly mutated disease-associated genes revealed that, compared with two truncating mutations, two missense mutations associated with less severe CKD in adults. Moreover, compared with mutations in BBS10, mutations in BBS1 associated with less severe CKD or lack of CKD in adults. Finally, 51% of patients with available ultrasounds had structural renal abnormalities, and 35% of adults were hypertensive. The presence of structural abnormalities or antihypertensive medication also correlated statistically with stage 3b-5 CKD. This study describes the largest reported cohort of patients with renal disease in Bardet-Biedl syndrome and identifies risk factors to be considered in genetic counseling.


Assuntos
Síndrome de Bardet-Biedl/complicações , Insuficiência Renal Crônica/epidemiologia , Insuficiência Renal Crônica/etiologia , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Mutação , Prevalência , Insuficiência Renal Crônica/genética , Estudos Retrospectivos , Fatores de Risco , Índice de Gravidade de Doença , Adulto Jovem
16.
Sci Signal ; 9(435): ra68, 2016 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-27382027

RESUMO

Malignant hyperthermia is a potentially fatal hypermetabolic disorder triggered by halogenated anesthetics and the myorelaxant succinylcholine in genetically predisposed individuals. About 50% of susceptible individuals carry dominant, gain-of-function mutations in RYR1 [which encodes ryanodine receptor type 1 (RyR1)], though they have normal muscle function and no overt clinical symptoms. RyR1 is predominantly found in skeletal muscle but also at lower amounts in immune and smooth muscle cells, suggesting that RYR1 mutations may have a wider range of effects than previously suspected. Mild bleeding abnormalities have been described in patients with malignant hyperthermia carrying gain-of-function RYR1 mutations. We sought to determine the frequency and molecular basis for this symptom. We found that some patients with specific RYR1 mutations had abnormally high bleeding scores, whereas their healthy relatives did not. Knock-in mice with the malignant hyperthermia susceptibility RYR1 mutation Y522S (MHS RYR1Y522S) had longer bleeding times than their wild-type littermates. Primary vascular smooth muscle cells from RYR1Y522S knock-in mice exhibited a higher frequency of subplasmalemmal Ca(2+) sparks, leading to a more negative resting membrane potential. The bleeding defect of RYR1Y522S mice and of one patient was reversed by treatment with the RYR1 antagonist dantrolene, and Ca(2+) sparks in primary vascular smooth muscle cells from the MHS RYR1Y522S mice were blocked by ryanodine or dantrolene. Thus, RYR1 mutations may lead to prolonged bleeding by altering vascular smooth muscle cell function. The reversibility of the bleeding phenotype emphasizes the potential therapeutic value of dantrolene in the treatment of such bleeding disorders.


Assuntos
Transtornos da Coagulação Sanguínea/metabolismo , Sinalização do Cálcio , Hipertermia Maligna/metabolismo , Músculo Liso Vascular/metabolismo , Mutação de Sentido Incorreto , Miócitos de Músculo Liso/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Substituição de Aminoácidos , Animais , Transtornos da Coagulação Sanguínea/genética , Transtornos da Coagulação Sanguínea/patologia , Dantroleno/farmacologia , Feminino , Humanos , Masculino , Hipertermia Maligna/genética , Hipertermia Maligna/patologia , Camundongos , Camundongos Mutantes , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/patologia , Canal de Liberação de Cálcio do Receptor de Rianodina/genética
17.
Recent Results Cancer Res ; 205: 1-15, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27075345

RESUMO

The ability to identify genetic mutations causing an increased risk of cancer represents the first widespread example of personalised medicine, in which genetic information is used to inform patients of their cancer risks and direct an appropriate strategy to minimise those risks. Increasingly, an understanding of the genetic basis of many cancers also facilitates selection of the most effective therapeutic options. The technology underlying genetic testing has been revolutionised in the years since the completion of the Human Genome Project in 2001. This has advanced knowledge of the genetic factors underlying familial cancer risk, and has also improved genetic testing capacity allowing a larger number of patients to be tested for a constitutional cancer predisposition. To use these tests safely and effectively, they must be assessed for their ability to provide accurate and useful results, and be requested and interpreted by health professionals with an understanding of their strengths and limitations. Genetic testing is increasing in its scope and ambition with each year that passes, requiring a greater proportion of the healthcare workforce to acquire a working knowledge of genetics and genetic testing to manage their patients safely and sensitively.


Assuntos
Testes Genéticos , Síndromes Neoplásicas Hereditárias/diagnóstico , Humanos , Síndromes Neoplásicas Hereditárias/genética , Participação do Paciente
18.
Proc Natl Acad Sci U S A ; 113(9): E1236-45, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26884178

RESUMO

Xeroderma pigmentosum (XP) is a rare DNA repair disorder characterized by increased susceptibility to UV radiation (UVR)-induced skin pigmentation, skin cancers, ocular surface disease, and, in some patients, sunburn and neurological degeneration. Genetically, it is assigned to eight complementation groups (XP-A to -G and variant). For the last 5 y, the UK national multidisciplinary XP service has provided follow-up for 89 XP patients, representing most of the XP patients in the United Kingdom. Causative mutations, DNA repair levels, and more than 60 clinical variables relating to dermatology, ophthalmology, and neurology have been measured, using scoring systems to categorize disease severity. This deep phenotyping has revealed unanticipated heterogeneity of clinical features, between and within complementation groups. Skin cancer is most common in XP-C, XP-E, and XP-V patients, previously considered to be the milder groups based on cellular analyses. These patients have normal sunburn reactions and are therefore diagnosed later and are less likely to adhere to UVR protection. XP-C patients are specifically hypersensitive to ocular damage, and XP-F and XP-G patients appear to be much less susceptible to skin cancer than other XP groups. Within XP groups, different mutations confer susceptibility or resistance to neurological damage. Our findings on this large cohort of XP patients under long-term follow-up reveal that XP is more heterogeneous than has previously been appreciated. Our data now enable provision of personalized prognostic information and management advice for each XP patient, as well as providing new insights into the functions of the XP proteins.


Assuntos
Xeroderma Pigmentoso/genética , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Heterogeneidade Genética , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Fenótipo , Reino Unido , Adulto Jovem
20.
Am J Med Genet A ; 167A(10): 2231-7, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26079862

RESUMO

De novo mutations (DNM) in SYNGAP1, encoding Ras/Rap GTPase-activating protein SynGAP, have been reported in individuals with nonsyndromic intellectual disability (ID). We identified 10 previously unreported individuals with SYNGAP1 DNM; seven via the Deciphering Developmental Disorders (DDD) Study, one through clinical analysis for copy number variation and the remaining two (monozygotic twins) via a research multi-gene panel analysis. Seven of the nine heterozygous mutations are likely to result in loss-of-function (3 nonsense; 3 frameshift; 1 whole gene deletion). The remaining two mutations, one of which affected the monozygotic twins, were missense variants. Each individual carrying a DNM in SYNGAP1 had moderate-to-severe ID and 7/10 had epilepsy; typically myoclonic seizures, absences or drop attacks. 8/10 had hypotonia, 5/10 had significant constipation, 7/10 had wide-based/unsteady gait, 3/10 had strabismus, and 2/10 had significant hip dysplasia. A proportion of the affected individuals had a similar, myopathic facial appearance, with broad nasal bridge, relatively long nose and full lower lip vermilion. A distinctive behavioral phenotype was also observed with aggressive/challenging behavior and significant sleep problems being common. 7/10 individuals had MR imaging of the brain each of which was reported as normal. The clinical features of the individuals reported here show significant overlap with those associated with 6p21.3 microdeletions, confirming that haploinsufficiency for SYNGAP1 is responsible for both disorders. © 2015 Wiley Periodicals, Inc.


Assuntos
Heterozigoto , Deficiência Intelectual/genética , Mutação , Proteínas Ativadoras de ras GTPase/genética , Adolescente , Criança , Pré-Escolar , Constipação Intestinal/diagnóstico , Constipação Intestinal/genética , Constipação Intestinal/patologia , Análise Mutacional de DNA , Epilepsias Mioclônicas/diagnóstico , Epilepsias Mioclônicas/genética , Epilepsias Mioclônicas/patologia , Feminino , Transtornos Neurológicos da Marcha/diagnóstico , Transtornos Neurológicos da Marcha/genética , Transtornos Neurológicos da Marcha/patologia , Expressão Gênica , Haploinsuficiência , Luxação do Quadril/diagnóstico , Luxação do Quadril/genética , Luxação do Quadril/patologia , Humanos , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/patologia , Masculino , Hipotonia Muscular/diagnóstico , Hipotonia Muscular/genética , Hipotonia Muscular/patologia , Fenótipo , Estrabismo/diagnóstico , Estrabismo/genética , Estrabismo/patologia , Gêmeos Monozigóticos
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