Genetic Causes of Putative Autosomal Recessive Intellectual Disability Cases in Hamedan Province

Objective: The aim of this study was to investigate the genetic causes of autosomal recessive intellectual disabilities (AR-ID) in Hamadan province of Iran. Materials & Methods: In this descriptive-analytical cross-sectional study, 25 families with more than one affected with putative autosomal recessive intellectual disability were chosen with collaboration of Welfare Organization of Hamadan province. Families were included a total of 60 patients (39 male and 21 female) whose intellectual disability had been confirmed by Raven IQ test. Each family was asked for clinical examination and getting consent form. Blood sample was collected from each family. One proband from each family was tested for CGG repeat expansion in FMR1 gene, chromosomal abnormalities and inborn errors of metabolism. We also performed homozygosity mapping based on STR markers for seven known MCPH loci in families with primary microcephaly and AR-ID. Results: Five families had full mutation of Fragile X syndrome. No chromosomal abnormalities were identified. Metabolic screening revealed one family with Medium Chain Acyl CoA Dehydrogenase deficiency. None of three families with primary microcephaly and AR-ID showed linkage to any of known seven MCPH loci. Conclusion: The main causes of ID in Hamadan province were Fragile X syndrome and Autosomal Recessive Primary Microcephaly with the frequencies of 20% and 12%, respectively

Genetic Causes of Mental Retardation in Bushehr Province

Objective: About 50% of severe to profound intellectual disabilities (ID) are caused by genetic factors. In this study we decided to investigate the genetic causes of ID in 69 Bushehrian families to provide information for genetic counseling, carrier detection, and prenatal diagnosis. Materials & Methods: In this study we excluded known chromosomal abnormalities. The majority of families had more than two affected individuals. Karyotyping for each proband with physical malformations was performed. One affected member from each family was tested for FMR1 mutation and metabolic screening. Families with ID and primary microcephaly were checked for 7 known MCPH genes by linkage analysis. Results: Chromosomal abnormality was not found in any of the families. One family had full mutation of CGG repeat of Fragile-X syndrome. Six out of 18 families with MCPH showed linkage to one of the MCPH loci. One family had a syndrome associated with microcephaly. Two families with microcephaly and one family with a non-syndromic form of mental retardation without microcephaly showed an autosomal dominant mode of inheritance. Conclusion: According to our results genetic causes of ID are very heterogeneous and autosomal recessive primary microcephaly has an extremely high prevalence (26.09%) in Bushehr province of Iran