The Roma (Gypsies) are a transnational minority, founder population characterized by unique genetic background modeled by culturally determined endogamy. The present study explores whether the widely found cardiovascular diseases (CVD) risk effects of ACE I/D, APOE (ε2, ε3, ε4), eNOS-VNTR and LEP G2548A polymorphisms can be replicated in this specific population. The community-based study was carried on 208 adult Bayash Roma living in rural settlements of eastern and northern Croatia. Risk effect of four CVD candidate polymorphisms are related to the most prominent classical CVD risk phenotypes: obesity indicators (body mass index and waist circumference), hypertension and hyperlipidemia (triglycerides, HDL and LDL cholesterol). For all of them the standard risk cut-offs were applied. The extent to which the phenotypic status is related to genotype was assessed by logistic regression analysis. The strongest associations were found for ε2 allele of the APOE as a predictor of waist circumference (OR 3.301; 95%CI 1.254-8.688; p = 0.016) as well as for BMI (OR 3.547; 95%CI 1.471-8.557; p = 0.005). It is notable that ε3 allele of APOE gene turned out to be a protective genetic factor determining low lipid levels. The strength of the relation and the similarity of the results obtained for both tested indicators of obesity provide firm evidence that APOE plays an important role in obesity development in the Roma population.

The products of the polymorphic ADME genes are involved in Absorption, Distribution, Metabolism, and Excretion of drugs. The pharmacogenetic data have been studied extensively due to their clinical importance in the appropriate drug prescription, but such data from the isolated populations are rather scarce. We analyzed the distribution of 95 polymorphisms in 31 core ADME genes in 20 populations worldwide and in newly genotyped samples from the Roma (Gypsy) population living in Croatia. Global distribution of ADME core gene loci differentiated three major clusters; (1) African, (2) East Asian, and (3) joint European, South Asian and South American cluster. The SLCO1B3 (rs4149117) and CYP3A4 (rs2242480) genes differentiated at the highest level the African group of populations, while NAT2 gene loci (rs1208, rs1801280, and rs1799929) and VKORC1 (rs9923231) differentiated East Asian populations. The VKORC1 rs9923231 was among the investigated loci the one with the largest global minor allele frequency (MAF) range; its MAF ranged from 0.027 in Nigeria to 0.924 in Han Chinese. The distribution of the investigated gene loci positions Roma population within the joined European and South Asian clusters, suggesting that their ADME gene pool is a combination of ancestral (Indian) and more recent (European) surrounding, as it was already implied by other genetic markers. However, when compared to the populations worldwide, the Croatian Roma have extreme MAF values in 10 out of the 95 investigated ADME core gene loci. Among loci which have extraordinary MAFs in Roma population two have strong proof of clinical importance: rs1799853 (CYP2C9) for warfarin dosage, and rs12248560 (CYP2C19) for clopidogrel dosage, efficacy and toxicity. This finding confirms the importance of taking the Roma as well as the other isolated populations`genetic profiles into account in pharmaco-therapeutic practice.

A significant portion of the variability in complex features, such as drug response, is likely caused by human genetic diversity. One of the highly polymorphic pharmacogenes is CYP2D6, encoding an enzyme involved in the metabolism of about 25% of commonly prescribed drugs. In a directed search of the 1000 Genomes Phase III variation data, 86 single nucleotide polymorphisms (SNPs) in the CYP2D6 gene were extracted from the genotypes of 2504 individuals from 26 populations, and then used to reconstruct haplotypes. Analyses were performed using Haploview, Phase, and Arlequin softwares. Haplotype and nucleotide diversity were high in all populations, but highest in populations of African ancestry. Pairwise F_ST showed significant results for eleven SNPs, six of which were characteristic of African populations, while four SNPs were most common in East Asian populations. A principal component analysis of CYP2D6 haplotypes showed that African populations form one cluster, Asian populations form another cluster with East and South Asian populations separated, while European populations form the third cluster. Linkage disequilibrium showed that all African populations have three or more haplotype blocks within the CYP2D6 gene, while other world populations have one, except for Chinese Dai and Punjabi in Pakistan populations, which have two.