RESUMO
Variants in CLCN4, which encodes the chloride/hydrogen ion exchanger CIC-4 prominently expressed in brain, were recently described to cause X-linked intellectual disability and epilepsy. We present detailed phenotypic information on 52 individuals from 16 families with CLCN4-related disorder: 5 affected females and 2 affected males with a de novo variant in CLCN4 (6 individuals previously unreported) and 27 affected males, 3 affected females and 15 asymptomatic female carriers from 9 families with inherited CLCN4 variants (4 families previously unreported). Intellectual disability ranged from borderline to profound. Behavioral and psychiatric disorders were common in both child- and adulthood, and included autistic features, mood disorders, obsessive-compulsive behaviors and hetero- and autoaggression. Epilepsy was common, with severity ranging from epileptic encephalopathy to well-controlled seizures. Several affected individuals showed white matter changes on cerebral neuroimaging and progressive neurological symptoms, including movement disorders and spasticity. Heterozygous females can be as severely affected as males. The variability of symptoms in females is not correlated with the X inactivation pattern studied in their blood. The mutation spectrum includes frameshift, missense and splice site variants and one single-exon deletion. All missense variants were predicted to affect CLCN4's function based on in silico tools and either segregated with the phenotype in the family or were de novo. Pathogenicity of all previously unreported missense variants was further supported by electrophysiological studies in Xenopus laevis oocytes. We compare CLCN4-related disorder with conditions related to dysfunction of other members of the CLC family.
Assuntos
Canais de Cloreto/genética , Síndromes Epilépticas/genética , Deficiência Intelectual/genética , Adolescente , Adulto , Idoso , Animais , Criança , Pré-Escolar , Canais de Cloreto/metabolismo , Epilepsia/genética , Síndromes Epilépticas/fisiopatologia , Família , Feminino , Genes Ligados ao Cromossomo X , Doenças Genéticas Ligadas ao Cromossomo X/genética , Mutação em Linhagem Germinativa , Humanos , Deficiência Intelectual/metabolismo , Masculino , Pessoa de Meia-Idade , Mutação , Oócitos , Linhagem , Fenótipo , Síndrome , Substância Branca/fisiopatologia , Xenopus laevisRESUMO
X-linked creatine transport (CRTR) deficiency, caused by mutations in the SLC6A8 gene, leads to intellectual disability, speech delay, epilepsy, and autistic behavior in hemizygous males. Additional diagnostic features are depleted brain creatine levels and increased creatine/creatinine ratio (cr/crn) in urine. In heterozygous females the phenotype is highly variable and diagnostic hallmarks might be inconclusive. This survey aims to explore the intrafamilial variability of clinical and brain proton Magnetic Resonance Spectroscopy (MRS) findings in males and females with CRTR deficiency. X-chromosome exome sequencing identified a novel missense mutation in the SLC6A8 gene (p.G351R) in a large family with X-linked intellectual disability. Detailed clinical investigations including neuropsychological assessment, measurement of in vivo brain creatine concentrations using quantitative MRS, and analyses of creatine metabolites in urine were performed in five clinically affected family members including three heterozygous females and one hemizygous male confirming the diagnosis of CRTR deficiency. The severe phenotype of the hemizygous male was accompanied by most distinct aberrations of brain creatine concentrations (-83% in gray and -79% in white matter of age-matched normal controls) and urinary creatine/creatinine ratio. In contrast, the heterozygous females showed varying albeit generally milder phenotypes with less severe brain creatine (-50% to -33% in gray and -45% to none in white matter) and biochemical urine abnormalities. An intrafamilial correlation between female phenotype, brain creatine depletion, and urinary creatine abnormalities was observed. The combination of powerful new technologies like exome-next-generation sequencing with thorough systematic evaluation of patients will further expand the clinical spectrum of neurometabolic diseases.
Assuntos
Craniossinostoses , Displasia Ectodérmica , Proteínas/genética , Osso e Ossos/anormalidades , Osso e Ossos/fisiopatologia , Criança , Craniossinostoses/genética , Craniossinostoses/fisiopatologia , Proteínas do Citoesqueleto , Displasia Ectodérmica/genética , Displasia Ectodérmica/fisiopatologia , Feminino , Proteínas Hedgehog , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , MutaçãoRESUMO
Attention-deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurodevelopmental syndrome characterized by hyperactivity, inattention and increased impulsivity. To detect micro-deletions and micro-duplications that may have a role in the pathogenesis of ADHD, we carried out a genome-wide screen for copy number variations (CNVs) in a cohort of 99 children and adolescents with severe ADHD. Using high-resolution array comparative genomic hybridization (aCGH), a total of 17 potentially syndrome-associated CNVs were identified. The aberrations comprise 4 deletions and 13 duplications with approximate sizes ranging from 110 kb to 3 Mb. Two CNVs occurred de novo and nine were inherited from a parent with ADHD, whereas five are transmitted by an unaffected parent. Candidates include genes expressing acetylcholine-metabolizing butyrylcholinesterase (BCHE), contained in a de novo chromosome 3q26.1 deletion, and a brain-specific pleckstrin homology domain-containing protein (PLEKHB1), with an established function in primary sensory neurons, in two siblings carrying a 11q13.4 duplication inherited from their affected mother. Other genes potentially influencing ADHD-related psychopathology and involved in aberrations inherited from affected parents are the genes for the mitochondrial NADH dehydrogenase 1 α subcomplex assembly factor 2 (NDUFAF2), the brain-specific phosphodiesterase 4D isoform 6 (PDE4D6) and the neuronal glucose transporter 3 (SLC2A3). The gene encoding neuropeptide Y (NPY) was included in a â¼3 Mb duplication on chromosome 7p15.2-15.3, and investigation of additional family members showed a nominally significant association of this 7p15 duplication with increased NPY plasma concentrations (empirical family-based association test, P=0.023). Lower activation of the left ventral striatum and left posterior insula during anticipation of large rewards or losses elicited by functional magnetic resonance imaging links gene dose-dependent increases in NPY to reward and emotion processing in duplication carriers. These findings implicate CNVs of behaviour-related genes in the pathogenesis of ADHD and are consistent with the notion that both frequent and rare variants influence the development of this common multifactorial syndrome.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Variações do Número de Cópias de DNA/genética , Dosagem de Genes/genética , Neuropeptídeo Y/genética , Linhagem , Adolescente , Transtorno do Deficit de Atenção com Hiperatividade/patologia , Encéfalo/irrigação sanguínea , Encéfalo/patologia , Criança , Mapeamento Cromossômico/métodos , Cromossomos Humanos Par 7/genética , Estudos de Coortes , Hibridização Genômica Comparativa/métodos , Saúde da Família , Feminino , Estudo de Associação Genômica Ampla/métodos , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética/métodos , Masculino , Neuropeptídeo Y/sangue , Oxigênio/sangue , FenótipoRESUMO
We report on a 30-year-old man with azoospermia, primary hypogonadism and minor dysmorphic features who carried a balanced insertional chromosome translocation inv ins (2p24;4q28.3q31.22)de novo. Molecular cytogenetic analyses of the chromosome breakpoints revealed the localization of the breakpoint in 4q28.3 between BACs RP11-143E9 and RP11-285A15, an interval that harbours the PCDH10 gene. In 4q31.22, a breakpoint-spanning clone (RP11-6L6) was identified which contains the genes LSM6 and SLC10A7. On chromosome 2, BACs RP11-531P14 and RP11-360O18 flank the breakpoint in 2p24, a region void of known genes. In conclusion, the chromosome aberration of this patient suggests a gene locus for primary hypogonadism in 2p24, 4q28.3 or 4q31.2, and three possible candidate genes (LSM6, SLC10A7 and PCDH10) were identified by breakpoint analyses.
Assuntos
Cromossomos Humanos Par 2/genética , Cromossomos Humanos Par 4/genética , Hipogonadismo/genética , Adulto , Caderinas/genética , Humanos , Hibridização in Situ Fluorescente , Masculino , Transportadores de Ânions Orgânicos Dependentes de Sódio/genética , Protocaderinas , Proteínas de Ligação a RNA/genética , Simportadores/genética , Translocação GenéticaRESUMO
BACKGROUND: Congenital heart disease (CHD) is the most common birth defect and affects nearly 1% of newborns. The aetiology of CHD is largely unknown and only a small percentage can be assigned to environmental risk factors such as maternal diseases or exposure to mutagenic agents during pregnancy. Chromosomal imbalances have been identified in many forms of syndromic CHD, but very little is known about the impact of DNA copy number changes in non-syndromic CHD. METHOD: A sub-megabase resolution array comparative genome hybridisation (CGH) screen was carried out on 105 patients with CHD as the sole abnormality at the time of diagnosis. RESULTS: There were 18 chromosomal changes detected, which do not coincide with common DNA copy number variants, including one de novo deletion, two de novo duplications and eight familial copy number variations (one deletion and seven duplications). CONCLUSIONS: Our data show that submicroscopic deletions and duplications play an important role in the aetiology of this condition, either as direct causes or as genetic risk factors for CHD. These findings have immediate consequences for genetic counselling and should pave the way for the elucidation of the pathogenetic mechanisms underlying CHD.
Assuntos
Aberrações Cromossômicas/estatística & dados numéricos , Hibridização Genômica Comparativa/métodos , Cardiopatias Congênitas/genética , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Criança , Deleção Cromossômica , Análise Citogenética , Feminino , Dosagem de Genes , Duplicação Gênica , Genoma Humano , Humanos , Lactente , Recém-Nascido , Masculino , FenótipoAssuntos
Alopecia/genética , Deficiência Intelectual/genética , Criança , Feminino , Ligação Genética , Humanos , Masculino , Linhagem , SíndromeRESUMO
Low copy repeats (LCRs) are stretches of duplicated DNA that are more than 1 kb in size and share a sequence similarity that exceeds 90%. Non-allelic homologous recombination (NAHR) between highly similar LCRs has been implicated in numerous genomic disorders. This study aimed at defining the impact of LCRs on the generation of balanced and unbalanced chromosomal rearrangements in mentally retarded patients. A cohort of 22 patients, preselected for the presence of submicroscopic imbalances, was analysed using submegabase resolution tiling path array CGH and the results were compared with a set of 41 patients with balanced translocations and breakpoints that were mapped to the BAC level by FISH. Our data indicate an accumulation of LCRs at breakpoints of both balanced and unbalanced rearrangements. LCRs with high sequence similarity in both breakpoint regions, suggesting NAHR as the most likely cause of rearrangement, were observed in 6/22 patients with chromosomal imbalances, but not in any of the balanced translocation cases studied. In case of chromosomal imbalances, the likelihood of NAHR seems to be inversely related to the size of the aberration. Our data also suggest the presence of additional mechanisms coinciding with or dependent on the presence of LCRs that may induce an increased instability at these chromosomal sites.
Assuntos
Aberrações Cromossômicas , Duplicação Gênica , Deficiência Intelectual/genética , Cromossomos Artificiais Bacterianos , Estudos de Coortes , Biologia Computacional/métodos , Genoma Humano , Humanos , Hibridização in Situ Fluorescente , Cariotipagem , Hibridização de Ácido Nucleico , Recombinação Genética , Translocação GenéticaRESUMO
We report a familial cryptic reciprocal translocation between 4q35 and 10p15 leading to deletion of the terminal long arm of chromosome 4 and duplication of the terminal short arm of chromosome 10 in two family members who both have immunological disturbances and a similar facial appearance. The precise location and extent of the deletion and duplication was determined by fluorescence in situ hybridization (FISH). Furthermore, we investigated the deletion breakpoint of a previously reported patient with 4q34.3-qter deletion [Van Buggenhout et al. (2004); Am J Med Genet Part A 131A:186-189].
Assuntos
Anormalidades Múltiplas/genética , Cromossomos Humanos Par 10/genética , Cromossomos Humanos Par 4/genética , Síndromes de Imunodeficiência/genética , Deficiência Intelectual/genética , Fenótipo , Translocação Genética/genética , Anormalidades Múltiplas/patologia , Adolescente , Adulto , Feminino , Humanos , Hibridização in Situ Fluorescente , Deficiência Intelectual/patologia , LinhagemAssuntos
Doenças Renais Císticas/patologia , Doenças Renais Císticas/fisiopatologia , Fenótipo , Adolescente , Cromossomos Humanos Par 17 , DNA/genética , Deleção de Genes , Fator 1-beta Nuclear de Hepatócito/genética , Humanos , Hibridização in Situ Fluorescente , Doenças Renais Císticas/genética , Masculino , Hibridização de Ácido Nucleico/métodosRESUMO
BACKGROUND: Characterisation of disease associated balanced chromosome rearrangements is a promising starting point in the search for candidate genes and regulatory elements. METHODS: We have identified and investigated three patients with limb abnormalities and breakpoints involving chromosome 2q31. Patient 1 with severe brachydactyly and syndactyly, mental retardation, hypoplasia of the cerebellum, scoliosis, and ectopic anus, carries a balanced t(2;10)(q31.1;q26.3) translocation. Patient 2, with translocation t(2;10)(q31.1;q23.33), has aplasia of the ulna, shortening of the radius, finger anomalies, and scoliosis. Patient 3 carries a pericentric inversion of chromosome 2, inv(2)(p15q31). Her phenotype is characterised by bilateral aplasia of the fibula and the radius, bilateral hypoplasia of the ulna, unossified carpal bones, and hypoplasia and dislocation of both tibiae. RESULTS: By fluorescence in situ hybridisation, we have mapped the breakpoints to intervals of approximately 170 kb or less. None of the three 2q31 breakpoints, which all mapped close to the HOXD cluster, disrupted any known genes. CONCLUSIONS: Hoxd gene expression in the mouse is regulated by cis-acting DNA elements acting over distances of several hundred kilobases. Moreover, Hoxd genes play an established role in bone development. It is therefore very likely that the three rearrangements disturb normal HOXD gene regulation by position effects.
Assuntos
Quebra Cromossômica/genética , Proteínas de Homeodomínio/genética , Deformidades Congênitas dos Membros/genética , Família Multigênica/genética , Adolescente , Adulto , Mapeamento Cromossômico , Cromossomos Humanos Par 2/genética , Biologia Computacional , Feminino , Humanos , Hibridização in Situ Fluorescente , Recém-Nascido , Cariotipagem , Masculino , Mutação/genética , Fatores de Transcrição/genéticaRESUMO
Truncating mutations were found in the PHF8 gene (encoding the PHD finger protein 8) in two unrelated families with X linked mental retardation (XLMR) associated with cleft lip/palate (MIM 300263). Expression studies showed that this gene is ubiquitously transcribed, with strong expression of the mouse orthologue Phf8 in embryonic and adult brain structures. The coded PHF8 protein harbours two functional domains, a PHD finger and a JmjC (Jumonji-like C terminus) domain, implicating it in transcriptional regulation and chromatin remodelling. The association of XLMR and cleft lip/palate in these patients with mutations in PHF8 suggests an important function of PHF8 in midline formation and in the development of cognitive abilities, and links this gene to XLMR associated with cleft lip/palate. Further studies will explore the specific mechanisms whereby PHF8 alterations lead to mental retardation and midline defects.
Assuntos
Cromossomos Humanos X , Fenda Labial/genética , Fissura Palatina/genética , Deficiência Intelectual Ligada ao Cromossomo X/genética , Fatores de Transcrição/genética , Animais , Histona Desmetilases , Humanos , Camundongos , Dados de Sequência Molecular , Estrutura Terciária de Proteína , Transcrição GênicaRESUMO
The sex determination system in mammals creates an imbalance between males and females in the number of X chromosomes. This imbalance is compensated through transcriptional silencing of one of the two X chromosomes in female diploid cells by epigenetic modifications. Although common for mammals, X inactivation shows marked species-specific differences in mechanisms and end results, and provides a unique opportunity to study epigenetic regulation of gene expression. The aim of the present study was to establish the expression pattern of selected X-linked genes in bovine fetal muscle tissue and muscle fibroblast cultures in order to follow possible modifications at the transcriptional level attributable to in vitro culture. We used heterologous cDNA microarray hybridization and quantitative real-time PCR to study the pattern of expression of X-linked genes including SLC25A6, GAB3, MECP2, RPS4X, JARID1C, UBE1, BIRC4 and SLC16A2. Quantitative real-time PCR analysis in fetal bovine muscle showed higher transcript levels in females for all X-linked genes tested with the exception of SLC25A6, with differences being significant for RPS4X, JARID1C and UBE1. The expression in fibroblast cultures derived from the same samples differed, with significantly higher levels for UBE1, GAB3 and BIRC4, while the rest of the panel of X-linked genes remained unchanged. The changed expression pattern in vitro, probably reflecting modifications in the epigenetic mechanisms that regulate transcriptional activity and gene silencing in X inactivation, has important implications for the advancement of new biotechnologies such as somatic cell nuclear transfer and stem cell therapy.
Assuntos
Fibroblastos/fisiologia , Músculo Esquelético/embriologia , Cromossomo X , Animais , Sequência de Bases , Biópsia , Bovinos , Mapeamento Cromossômico , Primers do DNA , DNA Complementar/genética , Feto , Fibroblastos/citologia , Músculo Esquelético/citologia , Músculo Esquelético/fisiologia , Hibridização de Ácido Nucleico , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase , RNA/genética , RNA/isolamento & purificação , Transcrição GênicaAssuntos
Proteínas de Ligação a DNA/genética , Deficiência Intelectual Ligada ao Cromossomo X/genética , Mutação , Fatores de Transcrição/genética , Linhagem Celular , Mapeamento Cromossômico , Cromossomos Humanos X , Análise Mutacional de DNA , Éxons , Feminino , Predisposição Genética para Doença , Humanos , Recém-Nascido , Íntrons , Fatores de Transcrição Kruppel-Like , Dados de Sequência Molecular , RNA Mensageiro/análise , Translocação GenéticaAssuntos
Ataxia Cerebelar/genética , Cromossomos Humanos Par 20/genética , Cromossomos Humanos Par 8/genética , Translocação Genética/genética , Adulto , Idade de Início , Ataxia Cerebelar/fisiopatologia , Criança , Pré-Escolar , Quebra Cromossômica/genética , Progressão da Doença , Feminino , Humanos , Hibridização in Situ Fluorescente , Lactente , Cariotipagem , Masculino , Pessoa de Meia-Idade , Linhagem , Mapeamento Físico do CromossomoRESUMO
Of 85 patients with ALS, the authors identified 3 patients with balanced translocations and 2 patients with pericentric inversions, all affecting distinct chromosomal loci. The high rate of constitutional aberrations (5.9%) suggests that ALS is, in part, associated with recombination-based rearrangements of genomic sequences.