RESUMO
The rs3129882, a noncoding variant in HLA-DR, was found to be associated with Parkinson's disease (PD) using several genome-wide association studies. The aim of this replication study was to explore the relationship between this variant and PD in Iranian population. Genomic DNA was extracted from peripheral blood samples, and the rs3129882 SNP was genotyped using a PCR-RFLP method in 520 PD patients and 520 healthy Iranian controls. Significant differences were found in allele frequencies between patients and controls (χ(2) = 4.64, P = 0.031). Under additive and dominant models, the association of the SNP with PD risk is significant, where the A allele was observed to be protective. The results suggest that rs3129882 polymorphism may be a risk factor for PD in Iranian. This is the first study reporting such an association in this population. More replication studies are needed to confirm this data.
Assuntos
Estudos de Associação Genética , Predisposição Genética para Doença , Cadeias alfa de HLA-DR/genética , Doença de Parkinson/genética , Alelos , Estudos de Casos e Controles , Feminino , Frequência do Gene/genética , Humanos , Padrões de Herança/genética , Irã (Geográfico) , Masculino , Pessoa de Meia-Idade , Modelos Genéticos , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
BACKGROUND: Primary microcephaly (MCPH) is a genetically heterogeneous disorder showing an autosomal recessive mode of inheritance. Affected individuals present with head circumferences more than three SDs below the age- and sex-matched population mean, associated with mild to severe mental retardation. Five genes (MCPH1, CDK5RAP2, ASPM, CENPJ, STIL) and two genomic loci, MCPH2 and MCPH4, have been identified so far. METHODS AND RESULTS: In this study, we investigated all seven MCPH loci in patients with primary microcephaly from 112 Consanguineous Iranian families. In addition to a thorough clinical characterisation, karyotype analyses were performed for all patients. For Homozygosity mapping, microsatellite markers were selected for each locus and used for genotyping. Our investigation enabled us to detect homozygosity at MCPH1 (Microcephalin) in eight families, at MCPH5 (ASPM) in thirtheen families. Three families showed homozygosity at MCPH2 and five at MCPH6 (CENPJ), and two families were linked to MCPH7 (STIL). The remaining 81 families were not linked to any of the seven known loci. Subsequent sequencing revealed eight, 10 and one novel mutations in Microcephalin, ASPM and CENPJ, respectively. In some families, additional features such as short stature, seizures or congenital hearing loss were observed in the microcephalic patient, which widens the spectrum of clinical manifestations of mutations in known microcephaly genes. CONCLUSION: Our results show that the molecular basis of microcephaly is heterogeneous; thus, the Iranian population may provide a unique source for the identification of further genes underlying this disorder.
Assuntos
Microcefalia/genética , Microcefalia/patologia , Adolescente , Adulto , Idoso , Proteínas de Ciclo Celular , Criança , Pré-Escolar , Proteínas do Citoesqueleto , Análise Mutacional de DNA , Família , Feminino , Genes Recessivos/genética , Loci Gênicos/genética , Genótipo , Humanos , Irã (Geográfico) , Cariotipagem , Masculino , Metáfase/genética , Pessoa de Meia-Idade , Mutação/genética , Proteínas do Tecido Nervoso/genética , Prófase/genética , Adulto JovemRESUMO
BACKGROUND: Intellectual disability (ID) has a worldwide prevalence of 1-3% and results from extraordinary heterogeneous. To shed more light on the causes of ID in Kerman Province, in Southeast Iran, we set out in 2008 to perform systematic clinical studies and homozygosity mapping in large Iranian families with ID. METHODS: Fifty seven families with a minimum of two mentally retarded children from Kerman Province were initially tested for metabolic disorders, by Tandem mass spectrometry. Fragile X testing and standard karyotyping were performed for all probands of families. Cases with autosomal recessive (AR) pattern of inheritance and microcephaly were subjected to homozygosity mapping by using several microsatellite markers for known MCPH loci. RESULTS: Three out of seven families with X-linked pattern of inheritance were positive for fragile X syndrome. Chromosome abnormality was not observed in any of dysmorphic patients and all families were negative for metabolic tests. Among the remaining 50 families of AR ID, six were found to be microcephalic, of which 2 linked to two MCPH loci (33.3%). The rest 4 families were not linked to any of the known loci. CONCLUSION: The results of this study showed that ID with microcephaly comprised 12% of ID cases in Kerman Province. In two families with apparent linkage to the MCPH5 and MCPH6 locus, mutation screening was not successful, which might indicate that either the mutation is located in the regulatory sequences of the gene or that there might be another genes present in these regions, which is mutated in such cases.