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1.
Genet Med ; 2021 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-33564150

RESUMO

PURPOSE: Noninvasive prenatal screening (NIPS) using cell-free DNA has transformed prenatal care. Belgium was the first country to implement and fully reimburse NIPS as a first-tier screening test offered to all pregnant women. A consortium consisting of all Belgian genetic centers report the outcome of two years genome-wide NIPS implementation. METHODS: The performance for the common trisomies and for secondary findings was evaluated based on 153,575 genome-wide NIP tests. Furthermore, the evolution of the number of invasive tests and the incidence of Down syndrome live births was registered. RESULTS: Trisomies 21, 18, and 13 were detected in respectively 0.32%, 0.07%, and 0.06% of cases, with overall positive predictive values (PPVs) of 92.4%, 84.6%, and 43.9%. Rare autosomal trisomies and fetal segmental imbalances were detected in respectively 0.23% and 0.07% of cases with PPVs of 4.1% and 47%. The number of invasive obstetric procedures decreased by 52%. The number of trisomy 21 live births dropped to 0.04%. CONCLUSION: Expanding the scope of NIPS beyond trisomy 21 fetal screening allows the implementation of personalized genomic medicine for the obstetric population. This genome-wide NIPS approach has been embedded successfully in prenatal genetic care in Belgium and might serve as a framework for other countries offering NIPS.

2.
J Bone Miner Res ; 2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32916022

RESUMO

Spondyloepimetaphyseal dysplasias (SEMDs) are a heterogeneous group of disorders with variable growth failure and skeletal impairments affecting the spine and long bone epiphyses and metaphyses. Here we report on four unrelated families with SEMD in which we identified two monoallelic missense variants and one monoallelic splice site variant in RPL13, encoding the ribosomal protein eL13. In two out of four families, we observed autosomal dominant inheritance with incomplete penetrance and variable clinical expressivity; the phenotypes of the mutation-positive subjects ranged from normal height with or without hip dysplasia to severe SEMD with severe short stature and marked skeletal dysplasia. In vitro studies on patient-derived dermal fibroblasts harboring RPL13 missense mutations demonstrated normal eL13 expression, with proper subcellular localization but reduced colocalization with eL28 (p < 0.001). Cellular functional defects in fibroblasts from mutation-positive subjects indicated a significant increase in the ratio of 60S subunits to 80S ribosomes (p = 0.007) and attenuated global translation (p = 0.017). In line with the human phenotype, our rpl13 mutant zebrafish model, generated by CRISPR-Cas9 editing, showed cartilage deformities at embryonic and juvenile stages. These findings extend the genetic spectrum of RPL13 mutations causing this novel human ribosomopathy with variable skeletal features. Our study underscores for the first time incomplete penetrance and broad phenotypic variability in SEMD-RPL13 type and confirms impaired ribosomal function. Furthermore, the newly generated rpl13 mutant zebrafish model corroborates the role of eL13 in skeletogenesis. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)..

3.
Artigo em Inglês | MEDLINE | ID: mdl-32601802

RESUMO

PURPOSE: To evaluate cerebral amyloid-ß(Aß) pathology in older adults with cognitive complaints, visual assessment of PET images is approved as the routine method for image interpretation. In research studies however, Aß-PET semi-quantitative measures are associated with greater risk of progression to dementia; but until recently, these measures lacked standardization. Therefore, the Centiloid scale, providing standardized Aß-PET semi-quantitation, was recently validated. We aimed to determine the predictive values of visual assessments and Centiloids in non-demented patients, using long-term progression to dementia as our standard of truth. METHODS: One hundred sixty non-demented participants (age, 54-86) were enrolled in a monocentric [18F] flutemetamol Aß-PET study. Flutemetamol images were interpreted visually following the manufacturers recommendations. SUVr values were converted to the Centiloid scale using the GAAIN guidelines. Ninety-eight persons were followed until dementia diagnosis or were clinically stable for a median of 6 years (min = 4.0; max = 8.0). Twenty-five patients with short follow-up (median = 2.0 years; min = 0.8; max = 3.9) and 37 patients with no follow-up were excluded. We computed ROC curves predicting subsequent dementia using baseline PET data and calculated negative (NPV) and positive (PPV) predictive values. RESULTS: In the 98 participants with long follow-up, Centiloid = 26 provided the highest overall predictive value = 87% (NPV = 85%, PPV = 88%). Visual assessment corresponded to Centiloid = 40, which predicted dementia with an overall predictive value = 86% (NPV = 81%, PPV = 92%). Inclusion of the 25 patients who only had a 2-year follow-up decreased the PPV = 67% (NPV = 88%), reflecting the many positive cases that did not progress to dementia after short follow-ups. CONCLUSION: A Centiloid threshold = 26 optimally predicts progression to dementia 6 years after PET. Visual assessment provides similar predictive value, with higher specificity and lower sensitivity. TRIAL REGISTRATION: Eudra-CT number: 2011-001756-12.

4.
Hum Mutat ; 41(9): 1615-1628, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32579715

RESUMO

Serine biosynthesis disorders comprise a spectrum of very rare autosomal recessive inborn errors of metabolism with wide phenotypic variability. Neu-Laxova syndrome represents the most severe expression and is characterized by multiple congenital anomalies and pre- or perinatal lethality. Here, we present the mutation spectrum and a detailed phenotypic analysis in 15 unrelated families with severe types of serine biosynthesis disorders. We identified likely disease-causing variants in the PHGDH and PSAT1 genes, several of which have not been reported previously. Phenotype analysis and a comprehensive review of the literature corroborates the evidence that serine biosynthesis disorders represent a continuum with varying degrees of phenotypic expression and suggest that even gradual differences at the severe end of the spectrum may be correlated with particular genotypes. We postulate that the individual residual enzyme activity of mutant proteins is the major determinant of the phenotypic variability, but further functional studies are needed to explore effects at the enzyme protein level.

5.
Eur J Med Genet ; 63(9): 103991, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32562872

RESUMO

Malformations of cortical development (MCD) represent a large group of brain cortical anomalies characterized by distinctive MRI findings. This 'radiologically-based' classification required re evaluation over time on identified underlying mechanisms (cytogenetic and/or molecular). The understanding of genotype findings (nature of cytogenetic/molecular mutation, cellular pathways consequences, timing, …) draw line of evidence on these distinctive group of conditions whereas sometimes precise and constant recurrent genotype/phenotype correlation may not be present. The clinical diagnosis of MCD is often difficult due to variability and rarity of individual types of malformations. Recent studies have established a relationship between lissencephaly and pathogenic variants in genes involved in the kinesin/tubulin pathways, as the KIF5C gene. Pathogenic variants in the KIF5C gene are a more recently discovered cause of severe developmental delay with epilepsy, characterized by specific malformation of cortical development such as pachygyria. Only seven children have been described to date. We report the natural history of a sixteen years old patient identified carrier of a KIF5C gene mutation who developed infantile epilepsy. We then gather phenotype description and molecular results of all reported patients so far in order to better define this entity.

6.
Prenat Diagn ; 40(10): 1272-1283, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32436253

RESUMO

OBJECTIVE: Belgian genetic centers established a database containing data on all chromosomal microarrays performed in a prenatal context. A study was initiated to evaluate postnatal development in children diagnosed prenatally with a non-benign copy number variant (CNV). METHODS: All children diagnosed with a prenatally detected non-benign CNV in a Belgian genetic center between May 2013 and February 2015 were included in the patient population. The control population consisted of children who had undergone an invasive procedure during pregnancy, with no or only benign CNVs. Child development was evaluated at 36 months using three (3) questionnaires: Ages and Stages Questionnaire Third edition, Ages and Stages Questionnaire Social-Emotional Second Edition and a general questionnaire. RESULTS: A significant difference in communication and personal-social development was detected between children with a reported susceptibility CNV and both children with an unreported susceptibility CNV and the control population. The outcome of children with a particular CNV is discussed in a case-by-case manner. CONCLUSION: Our postnatal follow-up project of children with a prenatally detected non-benign CNV is the first nationwide project of its kind. A higher number of cases for each CNV category is however needed to confirm our findings.

7.
Am J Med Genet C Semin Med Genet ; 181(4): 638-643, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31714006

RESUMO

BRWD3 has been described as a cause of X-linked intellectual disability, but relatively little is known about the specific phenotype. We report the largest BRWD3 patient series to date, comprising 17 males with 12 distinct null variants and 2 partial gene deletions. All patients presented with intellectual disability, which was classified as moderate (65%) or mild (35%). Behavioral issues were present in 75% of patients, including aggressive behavior, attention deficit/hyperactivity and/or autistic spectrum disorders. Mean head circumference was +2.8 SD (2.8 standard deviations above the mean), and mean BMI was +2.0 SD (in the context of a mean height of +1.3 SD), indicating a predominant macrocephaly/obesity phenotype. Shared facial features included a tall chin, prognathism, broad forehead, and prominent supraorbital ridge. Additional features, reported in a minority (<30%) of patients included cryptorchidism, neonatal hypotonia, and small joint hypermobility. This study delineates the clinical features associated with BRWD3 null variants and partial gene deletions, and suggests that BRWD3 should be included in the differential diagnosis of patients with an overgrowth-intellectual disability (OGID) phenotype, particularly in male patients with a mild or moderate intellectual disability associated with macrocephaly and/or obesity.


Assuntos
Deleção de Genes , Doenças Genéticas Ligadas ao Cromossomo X/genética , Deficiência Intelectual/genética , Megalencefalia/genética , Obesidade/genética , Fatores de Transcrição/genética , Adolescente , Criança , Humanos , Masculino , Índice de Gravidade de Doença , Síndrome
8.
Eur J Obstet Gynecol Reprod Biol ; 240: 232-241, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31336229

RESUMO

Antenatal diagnosis of cardio-facio-cutaneous syndrome: prenatal characteristics and contribution of fetal facial dysmorphic signs in utero. This paper is a case study and review of literature. "RASopathies" is the term coined for a group of genetic diseases that share modulation inside the MAPKinase pathway. Mutations inside the coding sequence of any of these genes may be responsible for the upregulation of the RAS pathway, leading on the clinical level to Type 1 Neurofibromatosis (NF1), Noonan syndrome (NS), Costello syndrome (CS), Multiple Lentigines, Loose Anagen Hair syndrome, Cardio-Facio-Cutaneous syndrome (CFCS), and, more recently, Legius syndrome. While the postnatal presentation of this group is well-known, prenatal findings are less well recognized. The presence of a RASopathy during the prenatal period can be suspected on account of non-specific abnormalities: polyhydramnios, cystic hygroma or high nuchal translucency, macrosomia with proportionate short long bones, macrocephaly, renal, lymphatic, or cardiac defects. The current case report underlines the characteristic dysmorphic facial features on 3D-ultrasound (hypertelorism, down-slanting palpebral fissures, a long and marked philtrum, and low-set posteriorly rotated ears) that allow for a "RASopathy" to be postulated. After detecting a copy number variation (CNV) absence on a CGH array, we performed a RASopathy gene panel analysis, which identified a so-far unreported heterozygous de novo mutation in the BRAF gene (namely NM_004333.4 : c.1396 G > C ; p.Gly466Arg). Genetic counseling has, therefore, focused on the diagnosis of a RASopathy and predictable phenotype of CFCS, a distinct entity characterized by an increased risk of intellectual disability and early-onset feeding problems. We suggest that a more detailed prenatal facial evaluation should be performed in fetuses presenting high nuchal thickness, heart defects, or unusual findings, along with the absence of a CNV on a CGH array. Due to the dysmorphic facial features, targeted RASopathy genes are presumed to likely to be responsible for NS, CFCS, and CS.


Assuntos
Displasia Ectodérmica/diagnóstico por imagem , Insuficiência de Crescimento/diagnóstico por imagem , Cardiopatias Congênitas/diagnóstico por imagem , Mutação , Proteínas Proto-Oncogênicas B-raf/genética , Adulto , Variações do Número de Cópias de DNA , Displasia Ectodérmica/genética , Facies , Insuficiência de Crescimento/genética , Feminino , Cardiopatias Congênitas/genética , Humanos , Gravidez , Diagnóstico Pré-Natal , Ultrassonografia Pré-Natal
9.
J Neuromuscul Dis ; 6(2): 241-258, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31127727

RESUMO

BACKGROUND: Neuromuscular disorders (NMDs) are clinically and genetically heterogeneous. Accurate molecular genetic diagnosis can improve clinical management, provides appropriate genetic counseling and testing of relatives, and allows potential therapeutic trials. OBJECTIVE: To establish the clinical utility of panel-based whole exome sequencing (WES) in NMDs in a population with children and adults with various neuromuscular symptoms. METHODS: Clinical exome sequencing, followed by diagnostic interpretation of variants in genes associated with NMDs, was performed in a cohort of 396 patients suspected of having a genetic cause with a variable age of onset, neuromuscular phenotype, and inheritance pattern. Many had previously undergone targeted gene testing without results. RESULTS: Disease-causing variants were identified in 75/396 patients (19%), with variants in the three COL6-genes (COL6A1, COL6A2 and COL6A3) as the most common cause of the identified muscle disorder, followed by variants in the RYR1 gene. Together, these four genes account for almost 25% of cases in whom a definite genetic cause was identified. Furthermore, likely pathogenic variants and/or variants of uncertain significance were identified in 95 of the patients (24%), in whom functional and/or segregation analysis should be used to confirm or reject the pathogenicity. In 18% of the cases with a disease-causing variant of which we received additional clinical information, we identified a genetic cause in genes of which the associated phenotypes did not match that of the patients. Hence, the advantage of panel-based WES is its unbiased approach. CONCLUSION: Whole exome sequencing, followed by filtering for NMD genes, offers an unbiased approach for the genetic diagnostics of NMD patients. This approach could be used as a first-tier test in neuromuscular disorders with a high suspicion of a genetic cause. With uncertain results, functional testing and segregation analysis are needed to complete the evidence.


Assuntos
Doenças Neuromusculares/diagnóstico , Doenças Neuromusculares/genética , Sequenciamento Completo do Exoma/métodos , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Adulto Jovem
10.
Genet Med ; 21(8): 1761-1771, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30670881

RESUMO

PURPOSE: ABCA4-associated disease, a recessive retinal dystrophy, is hallmarked by a large proportion of patients with only one pathogenic ABCA4 variant, suggestive for missing heritability. METHODS: By locus-specific analysis of ABCA4, combined with extensive functional studies, we aimed to unravel the missing alleles in a cohort of 67 patients (p), with one (p = 64) or no (p = 3) identified coding pathogenic variants of ABCA4. RESULTS: We identified eight pathogenic (deep-)intronic ABCA4 splice variants, of which five are novel and six structural variants, four of which are novel, including two duplications. Together, these variants account for the missing alleles in 40.3% of patients. Furthermore, two novel variants with a putative cis-regulatory effect were identified. The common hypomorphic variant c.5603A>T p.(Asn1868Ile) was found as a candidate second allele in 43.3% of patients. Overall, we have elucidated the missing heritability in 83.6% of our cohort. In addition, we successfully rescued three deep-intronic variants using antisense oligonucleotide (AON)-mediated treatment in HEK 293-T cells and in patient-derived fibroblast cells. CONCLUSION: Noncoding pathogenic variants, novel structural variants, and a common hypomorphic allele of the ABCA4 gene explain the majority of unsolved cases with ABCA4-associated disease, rendering this retinopathy a model for missing heritability in autosomal recessive disorders.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Genes Recessivos/genética , Oligonucleotídeos Antissenso/genética , Distrofias Retinianas/genética , Adulto , Alelos , Estudos de Coortes , Éxons/genética , Feminino , Frequência do Gene , Células HEK293 , Humanos , Íntrons/genética , Masculino , Pessoa de Meia-Idade , Mutação/genética , Oligonucleotídeos Antissenso/farmacologia , Linhagem , Fenótipo , Distrofias Retinianas/patologia
11.
Prenat Diagn ; 38(13): 1120-1128, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30334587

RESUMO

OBJECTIVE: With the replacement of karyotyping by chromosomal microarray (CMA) in invasive prenatal diagnosis, new challenges have arisen. By building a national database, we standardize the classification and reporting of prenatally detected copy number variants (CNVs) across Belgian genetic centers. This database, which will link genetic and ultrasound findings with postnatal development, forms a unique resource to investigate the pathogenicity of variants of uncertain significance and to refine the phenotypic spectrum of pathogenic and susceptibility CNVs. METHODS: The Belgian MicroArray Prenatal (BEMAPRE) consortium is a collaboration of all genetic centers in Belgium. We collected data from all invasive prenatal procedures performed between May 2013 and July 2016. RESULTS: In this three-year period, 13 266 prenatal CMAs were performed. By national agreement, a limited number of susceptibility CNVs and no variants of uncertain significance were reported. Added values for using CMA versus conventional karyotyping were 1.8% in the general invasive population and 2.7% in cases with an ultrasound anomaly. Of the reported CNVs, 31.5% would have remained undetected with non-invasive prenatal test as the first-tier test. CONCLUSION: The establishment of a national database for prenatal CNV data allows for a uniform reporting policy and the investigation of the prenatal and postnatal genotype-phenotype correlation.


Assuntos
Aberrações Cromossômicas , Anormalidades Congênitas/genética , Variações do Número de Cópias de DNA/genética , Haploinsuficiência/genética , Análise em Microsséries/métodos , Adulto , Artrogripose/diagnóstico , Artrogripose/genética , Bélgica , Doença de Charcot-Marie-Tooth/diagnóstico , Doença de Charcot-Marie-Tooth/genética , Hibridização Genômica Comparativa , Anormalidades Congênitas/diagnóstico , Bases de Dados Genéticas , Síndrome de DiGeorge/diagnóstico , Síndrome de DiGeorge/genética , Feminino , Predisposição Genética para Doença , Neuropatia Hereditária Motora e Sensorial/diagnóstico , Neuropatia Hereditária Motora e Sensorial/genética , Humanos , Ictiose Ligada ao Cromossomo X/diagnóstico , Ictiose Ligada ao Cromossomo X/genética , Cariotipagem , Gravidez , Diagnóstico Pré-Natal
12.
Horm Res Paediatr ; 89(6): 423-433, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29909407

RESUMO

Cushing syndrome (CS) is a rare disease in children, frequently associated with subtle or periodic symptoms that may delay its diagnosis. Weight gain and growth failure, the hallmarks of hypercortisolism in pediatrics, may be inconsistent, especially in ACTH-independent forms of CS. Primary pigmented nodular adrenocortical disease (PPNAD) is the rarest form of ACTH-independent CS, and can be associated with endocrine and nonendocrine tumors, forming the Carney complex (CNC). Recently, phenotype/genotype correlations have been described with particular forms of CNC where PPNAD is isolated or associated only with skin lesions. We present four familial series of CS due to isolated PPNAD, and compare them to available data from the literature. We discuss the clinical and molecular findings, and underline challenges in diagnosing PPNAD in childhood.


Assuntos
Doenças do Córtex Suprarrenal , Síndrome de Cushing , Adolescente , Doenças do Córtex Suprarrenal/diagnóstico , Doenças do Córtex Suprarrenal/genética , Doenças do Córtex Suprarrenal/patologia , Adulto , Criança , Pré-Escolar , Síndrome de Cushing/diagnóstico , Síndrome de Cushing/genética , Síndrome de Cushing/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
14.
Dermatol Pract Concept ; 8(1): 59-62, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29445579

RESUMO

LEOPARD syndrome, also known as Gorlin syndrome II, cardiocutaneous syndrome, lentiginosis profusa syndrome, Moynahan syndrome, was more recently coined as Noonan syndrome with multiple lentigines (NSML), inside the RASopathies. Historically, the acronym LEOPARD refers to the presence of distinctive clinical features such as: lentigines (L), electrocardiographic/conduction abnormalities (E), ocular hypertelorism (O), pulmonary stenosis (P), genital abnormalities (A), retardation of growth (R), and sensorineural deafness (D). This condition is identified in 85% of patients with phenotype hallmarks caused by presence a germline point mutation in PTPN11 gene. Association of melanoma to NSML seems to be rare: to our knowledge, two patients so far were reported in the literature. We herein present a patient diagnosed with LEOPARD syndrome, in whom molecular investigation confirmed the presence of the c.1403C>T mutation in exon 12 of the PTPN11 gene, who developed four superficial spreading melanomas and three atypical lentiginous hyperplasias. Three of the melanomas were achromic or hypochromic, three were in situ, and one had a Breslow index under 0.5 mm. Dermoscopic examination showed some characteristic white structures in most of the lesions, which were a signature pattern and a key for the diagnosis.

15.
Hum Mutat ; 39(3): 319-332, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29243349

RESUMO

Autosomal recessive microcephaly or microcephaly primary hereditary (MCPH) is a genetically heterogeneous neurodevelopmental disorder characterized by a reduction in brain volume, indirectly measured by an occipitofrontal circumference (OFC) 2 standard deviations or more below the age- and sex-matched mean (-2SD) at birth and -3SD after 6 months, and leading to intellectual disability of variable severity. The abnormal spindle-like microcephaly gene (ASPM), the human ortholog of the Drosophila melanogaster "abnormal spindle" gene (asp), encodes ASPM, a protein localized at the centrosome of apical neuroprogenitor cells and involved in spindle pole positioning during neurogenesis. Loss-of-function mutations in ASPM cause MCPH5, which affects the majority of all MCPH patients worldwide. Here, we report 47 unpublished patients from 39 families carrying 28 new ASPM mutations, and conduct an exhaustive review of the molecular, clinical, neuroradiological, and neuropsychological features of the 282 families previously reported (with 161 distinct ASPM mutations). Furthermore, we show that ASPM-related microcephaly is not systematically associated with intellectual deficiency and discuss the association between the structural brain defects (strong reduction in cortical volume and surface area) that modify the cortical map of these patients and their cognitive abilities.


Assuntos
Microcefalia/genética , Mutação/genética , Proteínas do Tecido Nervoso/genética , Pré-Escolar , Cognição , Estudos de Coortes , Família , Feminino , Estudos de Associação Genética , Geografia , Humanos , Lactente , Imagem por Ressonância Magnética , Masculino , Microcefalia/epidemiologia
16.
Int J Pediatr Otorhinolaryngol ; 104: 191-194, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29287866

RESUMO

CAPOS syndrome (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) is a rare neurological disorder, recently associated with the c.2452G > A hotspot mutation in the ATP1A3 gene, with sensorineural hearing loss as a prominent feature. We herein report on a girl who has experienced hearing loss for three years following an initial encephalitic episode when aged 15 months old. CAPOS was diagnosed only when she was six years old by targeted testing whilst she displayed optic atrophy, cerebellar signs and areflexia. CAPOS syndrome should be considered in the differential diagnosis of acquired childhood deafness, prompting clinicians to search for associated neurological features.


Assuntos
Ataxia Cerebelar/diagnóstico , Deformidades Congênitas do Pé/diagnóstico , Perda Auditiva Neurossensorial/etiologia , Atrofia Óptica/diagnóstico , Ataxia Cerebelar/complicações , Criança , Diagnóstico Diferencial , Feminino , Deformidades Congênitas do Pé/complicações , Perda Auditiva Neurossensorial/complicações , Perda Auditiva Neurossensorial/diagnóstico , Testes Auditivos , Humanos , Mutação , Atrofia Óptica/complicações , Reflexo Anormal , ATPase Trocadora de Sódio-Potássio/genética
17.
Brain ; 140(6): 1579-1594, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28444220

RESUMO

Autosomal dominant cerebellar ataxias have a marked heterogeneous genetic background, with mutations in 34 genes identified so far. This large amount of implicated genes accounts for heterogeneous clinical presentations, making genotype-phenotype correlations a major challenge in the field. While polyglutamine ataxias, linked to CAG repeat expansions in genes such as ATXN1, ATXN2, ATXN3, ATXN7, CACNA1A and TBP, have been extensively characterized in large cohorts, there is a need for comprehensive assessment of frequency and phenotype of more 'conventional' ataxias. After exclusion of CAG/polyglutamine expansions in spinocerebellar ataxia genes in 412 index cases with dominantly inherited cerebellar ataxias, we aimed to establish the relative frequencies of mutations in other genes, with an approach combining panel sequencing and TaqMan® polymerase chain reaction assay. We found relevant genetic variants in 59 patients (14.3%). The most frequently mutated were channel genes [CACNA1A (n = 16), KCND3 (n = 4), KCNC3 (n = 2) and KCNA1 (n = 2)]. Deletions in ITPR1 (n = 11) were followed by biallelic variants in SPG7 (n = 9). Variants in AFG3L2 (n = 7) came next in frequency, and variants were rarely found in STBN2 (n = 2), ELOVL5, FGF14, STUB1 and TTBK2 (n = 1 each). Interestingly, possible risk factor variants were detected in SPG7 and POLG. Clinical comparisons showed that ataxias due to channelopathies had a significantly earlier age at onset with an average of 24.6 years, versus 40.9 years for polyglutamine expansion spinocerebellar ataxias and 37.8 years for SPG7-related forms (P = 0.001). In contrast, disease duration was significantly longer in the former (20.5 years versus 9.3 and 13.7, P=0.001), though for similar functional stages, indicating slower progression of the disease. Of interest, intellectual deficiency was more frequent in channel spinocerebellar ataxias, while cognitive impairment in adulthood was similar among the three groups. Similar differences were found among a single gene group, comparing 23 patients with CACNA1A expansions (spinocerebellar ataxia 6) to 22 patients with CACNA1A point mutations, which had lower average age at onset (25.2 versus 47.3 years) with longer disease duration (18.7 versus 10.9), but lower severity indexes (0.39 versus 0.44), indicating slower progression of the disease. In conclusion, we identified relevant genetic variations in up to 15% of cases after exclusion of polyglutamine expansion spinocerebellar ataxias, and confirmed CACNA1A and SPG7 as major ataxia genes. We could delineate firm genotype-phenotype correlations that are important for genetic counselling and of possible prognostic value.


Assuntos
Canais de Cálcio/genética , Ataxia Cerebelar/genética , Ataxia Cerebelar/fisiopatologia , Canalopatias/genética , Canalopatias/fisiopatologia , Metaloendopeptidases/genética , ATPases Associadas a Diversas Atividades Celulares , Adolescente , Adulto , Idade de Início , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Genes Dominantes , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Adulto Jovem
18.
J Clin Invest ; 127(3): 912-928, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28165339

RESUMO

Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in SGPL1, which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representing SGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficient dpl1Δ yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown of Sgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. In Drosophila, Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WT Sply, but not the disease-associated variants, rescued this phenotype. Together, these results indicate that SGPL1 mutations cause a syndromic form of SRNS.


Assuntos
Aldeído Liases , Movimento Celular/genética , Ictiose Lamelar , Células Mesangiais/enzimologia , Mutação , Síndrome Nefrótica , Aldeído Liases/genética , Aldeído Liases/metabolismo , Animais , Linhagem Celular , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Feminino , Humanos , Ictiose Lamelar/enzimologia , Ictiose Lamelar/genética , Ictiose Lamelar/patologia , Masculino , Células Mesangiais/patologia , Camundongos , Camundongos Knockout , Síndrome Nefrótica/enzimologia , Síndrome Nefrótica/genética , Síndrome Nefrótica/patologia , Transporte Proteico/genética , Ratos
20.
Hum Mutat ; 38(5): 581-593, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28236341

RESUMO

Waardenburg syndrome (WS) is a genetic disorder characterized by sensorineural hearing loss and pigmentation anomalies. The clinical definition of four WS types is based on additional features due to defects in structures mostly arising from the neural crest, with type I and type II being the most frequent. While type I is tightly associated to PAX3 mutations, WS type II (WS2) remains partly enigmatic with mutations in known genes (MITF, SOX10) accounting for only 30% of the cases. We performed exome sequencing in a WS2 index case and identified a heterozygous missense variation in EDNRB. Interestingly, homozygous (and very rare heterozygous) EDNRB mutations are already described in type IV WS (i.e., in association with Hirschsprung disease [HD]) and heterozygous mutations in isolated HD. Screening of a WS2 cohort led to the identification of an overall of six heterozygous EDNRB variations. Clinical phenotypes, pedigrees and molecular segregation investigations unraveled a dominant mode of inheritance with incomplete penetrance. In parallel, cellular and functional studies showed that each of the mutations impairs the subcellular localization of the receptor or induces a defective downstream signaling pathway. Based on our results, we now estimate EDNRB mutations to be responsible for 5%-6% of WS2.


Assuntos
Estudos de Associação Genética , Heterozigoto , Mutação , Receptor de Endotelina B/genética , Síndrome de Waardenburg/diagnóstico , Síndrome de Waardenburg/genética , Adolescente , Adulto , Substituição de Aminoácidos , Criança , Pré-Escolar , Biologia Computacional/métodos , Análise Mutacional de DNA , Exoma , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Espaço Intracelular/metabolismo , Iris , Masculino , Taxa de Mutação , Linhagem , Fenótipo , Transporte Proteico , Sítios de Splice de RNA , Receptor de Endotelina B/metabolismo , Adulto Jovem
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