Intronic Polymorphisms in the CDKN2B-AS1 Gene Are Strongly Associated with the Risk of Myocardial Infarction and Coronary Artery Disease in the Saudi Population.

Recent genome-wide association studies identified single nucleotide polymorphisms (SNPs) on the chromosome 9p21.3 conferring the risk for CAD (coronary artery disease) in individuals of Caucasian ancestry. We performed a genetic association study to investigate the effect of 12 candidate SNPs within 9p21.3 locus on the risk of CAD in the Saudi population of the Eastern Province of Saudi Arabia. A total of 250 Saudi CAD patients who had experienced an myocardial infarction (MI) and 252 Saudi age-matched healthy controls were genotyped using TaqMan assay. Controls with evidenced lack of CAD provided 90% of statistical power at the type I error rate of 0.05. Five percent of the results were rechecked for quality control using Sanger sequencing, the results of which concurred with the TaqMan genotyping results. Association analysis of 12 SNPs indicated a significant difference in the genotype distribution for four SNPs between cases and controls (rs564398 p = 0.0315, χ² = 4.6, odds ratio (OD) = 1.5; rs4977574 p = 0.0336, χ² = 4.5, OD = 1.4; rs2891168 p = 1.85 × 10 - 10, χ² = 40.6, OD = 2.1 and rs1333042 p = 5.14 × 10 - 9, χ² = 34.1, OD = 2.2). The study identified three protective haplotypes (TAAG p = 1.00 × 10 - 4; AGTA p = 0.022 and GGGCC p = 0.0175) and a risk haplotype (TGGA p = 2.86 × 10 - 10) for the development of CAD. This study is in line with others that indicated that the SNPs located in the intronic region of the CDKN2B-AS1 gene are associated with CAD.

Co-inheritance of novel ATRX gene mutation and globin (α & ß) gene mutations in transfusion dependent beta-thalassemia patients.

α-Thalassemia X-linked mental retardation syndrome is a rare inherited intellectual disability disorder due to mutations in the ATRX gene. In our previous study of the prevalence of ß-thalassemia mutations in the Eastern Province of Saudi Arabia, we confirmed the widespread coinheritance of α-thalassemia mutation. Some of these subjects have a family history of mental retardation, the cause of which is unknown. Therefore, we investigated the presence or absence of mutations in the ATRX gene in these patients. Three exons of the ATRX gene and their flanking regions were directly sequenced. Only four female transfusion dependent ß-thalassemia patients were found to be carriers of a novel mutation in the ATRX gene. Two of the ATRX gene mutations, c.623delA and c.848T>C were present in patients homozygous for IVS I-5(G→C) and homozygous for Cd39(C → T) ß-thalassemia mutation, respectively. While the other two that were located in the intronic region (flanking regions), were present in patients homozygous for Cd39(C → T) ß-thalassemia mutation. The two subjects with the mutations in the coding region had family members with mental retardation, which suggests that the novel frame shift mutation and the missense mutation at coding region of ATRX gene are involved in ATRX syndrome.