A comprehensive study of phenylalanine hydroxylase gene mutations in the Iranian phenylketonuria patients.

Phenylketonuria (PKU) is a metabolic disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene. After thalassemia, PKU is considered as the most common autosomal recessive diseases in the Iranian population. Therefore, an efficient diagnostic strategy is required to identify disease-causing mutations in this population. Following our first report in 2003, here we presented a comprehensive study on the mutation spectrum of the PAH gene in the Iranian population. This study was performed on 280 unrelated chromosomes from 140 Iranian patients with classic PKU. All 13 exons as well as exon-intron boundaries of the PAH gene were analyzed by direct DNA sequencing. Thirty four different mutations were identified by a mutation detection rate of 100%. IVS10-11G > A, p.P281L, R261Q, p.F39del and IVS11+1G > C were the most prevalent mutations with frequencies of 26.07%, 19.3%, 12.86%, 6.07 and 3.93%, respectively. All other mutations represented a relative frequency less than 3.5%. The data from this study provided a comprehensive spectrum of the PAH gene mutations which can facilitate carrier detection and prenatal diagnosis of PKU disease in the Iranian population.

Characterization and specification of microsatellite markers in the HLA-DRB1 gene region: a revision to major histocompatibility complex database.

Association between HLA-DRB1 and a large number of diseases such as multiple sclerosis, type I diabetes and rheumatoid arthritis has been demonstrated. In the present study, we attempted to identify and characterize potential microsatellites in the HLA-DRB1 gene region to find specific markers for genotyping and linkage analysis of this gene. The microsatellites including M2_3_22, M2_2_36, D6S2878, D6S2805, D6S2879 and D6S2880 were selected from microsatellite resource in the Major Histocompatibility Complex database (dbMHC). In silico analysis showed that only M2_3_22 was specific for HLA-DRB1. Moreover, our findings revealed some more accurate characteristics of the other investigated microsatellites. M2_3_22 existed as a single copy in all the MHC haplotype sequences and was located next to HLA-DRB1. Therefore, a new set of primers compatible with all the last published MHC haplotype sequences were designed and used to amplify M2_3_22 in 164 DNA samples obtained from unrelated Iranian individuals. M2_3_22 was successfully amplified in all DNA samples and three different alleles were identified. This locus was found in the Hardy-Weinberg equilibrium (P>0.05) in the studied population. Together, the findings suggested that M2_3_22 could be introduced as a specific locus in the HLA-DRB1 gene region for linkage analysis and disease association studies.