Five Polymorphisms of the Apolipoprotein B Gene in Healthy Bulgarians

Five APOB polymorphisms (I/D in the promoter region, XbaI [codon 2488], MspI [codon 3611], EcoRI [codon 4154], and 3′ VNTRs) were studied in a population sample of 147 healthy normolipemic Bulgarians. For all biallelic loci, the observed genotype distributions do not deviate from Hardy-Weinberg equilibrium. In Bulgaria the insertion allele and the MspI+ allele of APOB presented the highest allelic frequencies (0.793 ± 0.024 and 0.959 ± 0.012, respectively) among the European population groups studied so far. The allele frequencies of the other two biallelic polymorphisms (XbaI and EcoRI) found in the Bulgarian population are similar to those previously described in other Caucasian populations. Analysis of the 3′ VNTR polymorphism revealed 11 different alleles. Like studies in other Caucasian populations, this study found bimodal allele-size distribution and a high level of heterozygosity. The frequency of allele *31 (0.162 ± 0.022) among Bulgarians is higher than that of any other European population group studied so far. Genetic distances between Bulgarians and each of six populations from southeastern Europe for which 3′ VNTR allele frequencies are available showed an increase in the order: Albanian

Elevated levels of DNA methylation at the OPRM1 promoter in blood and sperm from male opioid addicts

OBJECTIVE: The OPRM1 gene was studied for DNA methylation in opioid dependence and possible paternal contribution to epigenetic inheritance of altered methylation profiles. PARTICIPANTS AND METHODS: DNA was extracted from blood and sperm from 13 male opioid addicts and 21 male control subjects. DNA methylation was determined by pyrosequencing in 24 CpG sites at the OPRM1 promoter region. RESULTS: The authors found significantly increased overall methylation in blood DNA from addicted subjects (Kruskal-Wallis [K-W] p = 0.013) Seven CpG sites showed significantly hypermethylated blood DNA from cases when compared with blood DNA controls (p < 0.05 at CpGs 5, 9, 10, 11, 18, 23, and 24). In sperm-derived DNA from addicts, the methylation was significantly increased at CpG 2 (p = 0.012), and overall methylation did not reach significant difference ( K-W p = 0.523). CONCLUSIONS: Increased DNA methylation in the OPRM1 gene is associated with opioid dependence. Hypermethylated CpG sites located in OPRM1 promoter may potentially block the binding of Sp1 and other transcription activators, thus leading to OPRM1 silencing. The increased DNA methylation in sperm may suggest a way of epigenetic heritability of opioid abuse or dependence phenotypes