Interethnic variability of CYP4F2 (V433M) in admixed population of Roma and Hungarians.

AIMS: Pharmacogenetic based dosing recommendations are provided in FDA-approved warfarin label for Caucasians. Evidence of notable difference in dosing algorithms of under-represented populations forced us to explore the genetic variability of CYP4F2 gene in Roma and Hungarian populations. PATIENTS AND METHODS: 484 Roma, 493 Hungarian untreated subjects were genotyped for the CYP4F2*3 (rs2108622) variant by PCR-RFLP assay. RESULTS AND DISCUSSION: We firstly report, that frequencies of the CYP4F2 rs2108622 GG, GA, AA genotypes and A allele in the Roma population were 46.5%, 42.6%, 10.9% and 32.2%; in Hungarians 50.1%, 42.2%, 7.7% and 22.8%, respectively. Bearing of two minor alleles of CYP4F2 missense variant (AA genotype) modestly explains inter-ethnic differences of studied populations (p<0.08). CYP4F2*3 (V433M) risk allele frequency of Roma (0.32) was in higher range, and of Hungarians (0.23) in lower range, as compared with other world populations. CONCLUSIONS: Roma have an elevated chance for higher mean warfarin dose, besides a decreased risk of major bleeding events in long-term warfarin use.

MARVELD2 (DFNB49) mutations in the hearing impaired Central European Roma population--prevalence, clinical impact and the common origin.

BACKGROUND: In the present study we aimed: 1) To establish the prevalence and clinical impact of DFNB49 mutations in deaf Roma from 2 Central European countries (Slovakia and Hungary), and 2) to analyze a possible common origin of the c.1331+2T>C mutation among Roma and Pakistani mutation carriers identified in the present and previous studies. METHODS: We sequenced 6 exons of the MARVELD2 gene in a group of 143 unrelated hearing impaired Slovak Roma patients. Simultaneously, we used RFLP to detect the c.1331+2T>C mutation in 85 Hungarian deaf Roma patients, control groups of 702 normal hearing Romanies from both countries and 375 hearing impaired Slovak Caucasians. We analyzed the haplotype using 21 SNPs spanning a 5.34Mb around the mutation c.1331+2T>C. RESULTS: One pathogenic mutation (c.1331+2T>C) was identified in 12 homozygous hearing impaired Roma patients. Allele frequency of this mutation was higher in Hungarian (10%) than in Slovak (3.85%) Roma patients. The identified common haplotype in Roma patients was defined by 18 SNP markers (3.89 Mb). Fourteen common SNPs were also shared among Pakistani and Roma homozygotes. Biallelic mutation carriers suffered from prelingual bilateral moderate to profound sensorineural hearing loss. CONCLUSIONS: We demonstrate different frequencies of the c.1331+2T>C mutation in hearing impaired Romanies from 3 Central European countries. In addition, our results provide support for the hypothesis of a possible common ancestor of the Slovak, Hungarian and Czech Roma as well as Pakistani deaf patients. Testing for the c.1331+2T>C mutation may be recommended in GJB2 negative Roma cases with early-onset sensorineural hearing loss.

Functional variants of lipid level modifier MLXIPL, GCKR, GALNT2, CILP2, ANGPTL3 and TRIB1 genes in healthy Roma and Hungarian populations.

The role of triglyceride metabolism in different diseases, such as cardiovascular or cerebrovascular diseases is still under extensive investigations. In genome-wide studies several polymorphisms have been reported, which are highly associated with plasma lipid level changes. Our goal was to examine eight variants: rs12130333 at the ANGPTL3, rs16996148 at the CILP2, rs17321515 at the TRIB1, rs17145738 and rs3812316 of the MLXIPL, rs4846914 at GALNT2, rs1260326 and rs780094 residing at the GCKR loci. A total of 399 Roma (Gypsy) and 404 Hungarian population samples were genotyped using PCR-RFLP method. Significant differences were found between Roma and Hungarian population samples in both MLXIPL variants (C allele frequency of rs17145738: 94.1% vs. 85.6%, C allele frequency of rs3812316: 94.2% vs. 86.8% in Romas vs. in Hungarians, p < 0.05), in ANGPTL3 (T allele frequency of rs1213033: 12.2% vs. 18.5% in Romas vs. Hungarians, p < 0.05) and GALNT2 (G allele frequency of rs4846914: 46.6% vs. 54.5% Romas vs. in Hungarians, p < 0.05), while no differences over SNPs could be verified and the known minor alleles showed no correlation with triglyceride levels in any population samples. The current study revealed fundamental differences of known triglyceride modifying SNPs in Roma population. Failure of finding evidence for affected triglyceride metabolism shows that these susceptibility genes are much less effective compared for example to the apolipoprotein A5 gene.

Significant interethnic differencies in functional variants of PON1 and P2RY12 genes in Roma and Hungarian population samples.

Antiplatelet therapy with clopidogrel is one of the most common therapies given to patients worldwide. However, the clinical efficacy and toxicity of clopidogrel is not constant in every patient due to interindividual variations. There are several factors that contribute to these interindividual differencies such as SNPs in genes of specific receptors and enzymes. PON1 (paraoxonase 1) plays an important role in the bioactivation of clopidogrel. Single nucleotide polymorphisms of this gene decrease the activity of paraoxonase enzyme and lead to an unefficient clopidogrel effect. P2RY12 (purinergic receptor P2Y, G-protein coupled, 12) gene is coding a receptor, which is situated on the surface of the platelets and plays a role in ADP-induced platelet aggregation. In this study we investigated 2 functional SNPs of PON1 gene (rs662 and rs854560) and 3 variants of the P2RY12 gene (rs2046934, rs6798347, rs6801273) in samples pooled from average Hungarian Roma and Hungarian population samples with PCR-RFLP method. For the PON1 variants we detected that the R allele frequency was significantly lower in the Roma group compared to the Hungarian population. (0.249 vs 0.318 p < 0.001). By contrast, the frequency of the M allele was significantly higher in Roma than in Hungarians (0.332 vs 0.290 p < 0.05). For the 3 P2RY12 variants we could find significant differencies only in rs2046934: the frequency of the CC genotype is 7 times higher in Hungarians than in Romas (1.4 vs 0.2 %, p < 0.05). The data presented here represent a unique genetic profile in Roma people that has not been reported for other populations.

Retrospective assessment of the most common mitochondrial DNA mutations in a large Hungarian cohort of suspect mitochondrial cases.

Prevalence estimations for mitochondrial disorders still vary widely and only few epidemiologic studies have been carried out so far. With the present work we aim to give a comprehensive overview about frequencies of the most common mitochondrial mutations in Hungarian patients. A total of 1328 patients were tested between 1999 and 2012. Among them, 882 were screened for the m.3243A > G, m.8344A > G, m.8993T > C/G mutations and deletions, 446 for LHON primary mutations. The mutation frequency in our cohort was 2.61% for the m.3243A > G, 1.47% for the m.8344A > G, 17.94% for Leber's Hereditary Optic Neuropathy (m.3460G > A, m.11778G > A, m.14484T > C) and 0.45% for the m.8993T > C/G substitutions. Single mtDNA deletions were detected in 14.97%, while multiple deletions in 6.01% of the cases. The mutation frequency in Hungarian patients suggestive of mitochondrial disease was similar to other Caucasian populations. Further retrospective studies of different populations are needed in order to accurately assess the importance of mitochondrial diseases and manage these patients.

Lower carrier rate of GJB2 W24X ancestral Indian mutation in Roma samples from Hungary: implication for public health intervention.

The purpose of this work was to characterise the W24X mutation of the GJB2 gene in order to provide more representative and geographicaly relevant carrier rates of healthy Roma subisolates and the Hungarian population. 493 Roma and 498 Hungarian healthy subjects were genotyped for the GJB2 c.71G>A (rs104894396, W24X) mutation by PCR-RFLP assay and direct sequencing. This is the first report on GJB2 W24X mutation in geographically subisolated Roma population of Hungary compared to local Hungarians. Comparing the genotype and allele frequencies of GJB2 rs104894396 mutation, significant difference was found in GG (98.4 vs. 99.8 %), GA (1.62 vs. 0.20 %) genotypes and A (0.8 vs. 0.1 %) allele between the Roma and Hungarian populations, respectively (p < 0.02). None of the subjects of Roma and Hungarian samples carried the GJB2 W24X AA genotype. Considerable result of our study, that the proportion of GJB2 W24X GA heterozygotes and the A allele frequency was eight times higher in Roma than in Hungarians. Considering the results, the mutant allele frequency both in Roma (0.8 %) and in Hungarian (0.1 %) populations is lower than expected from previous results, likely reflecting local differentiated subisolates of these populations and a suspected lower risk for GJB2 mutation related deafness. However, the significant difference in GJB2 W24X carrier rates between the Roma and Hungarians may initiate individual diagnostic investigations and effective public health interventions.

High prevalence of CYP2C19*2 allele in Roma samples: study on Roma and Hungarian population samples with review of the literature.

The purpose of our study was to characterise the CYP2C19*2 and CYP2C19*3 alleles in healthy Roma and Hungarian populations. DNA of 500 Roma and 370 Hungarian subjects were genotyped for CYP2C19*2 (G681A, rs4244285) and CYP2C19*3 (G636A, rs4986893) by PCR-RFLP assay and direct sequencing. Significant differences were found comparing the Roma and Hungarian populations in CYP2C19 681 GG (63.6 vs. 75.9%), GA (31.8 vs. 23.0%), AA (4.6 vs. 1.1%), GA+AA (36.4 vs. 24.1%) and A allele frequencies (0.205 vs. 0.125) (p<0.004). Striking differences were found between Roma and Hungarian samples in CYP2C19*1 (79.5 vs. 87.4%) and CYP2C19*2 (20.5 vs. 12.6%) alleles, respectively (p<0.001). None of the subjects was found to carry the CYP2C19*3 allele. Frequencies of the intermedier metabolizer phenotype defined by the *1/*2 genotype (0.318 vs. 0.230, p<0.005) and poor metabolizer predicted by the *2/*2 genotype (0.046 vs. 0.011, p<0.005) was significantly higher in Roma than in Hungarians, respectively. Genotype distribution of the Roma population was similar to those of the population of North India, however, a major difference was found in the frequency of the CYP2C19*2 allele, which is likely a result of admixture with European lineages. In conclusion, the frequencies of the CYP2C19 alleles, genotypes and corresponding extensive, intermediate and poor metabolizer phenotypes studied here in the Hungarian population are similar to those of other European Caucasian populations, but display clear differences when compared to the Roma population.

Common functional variants of APOA5 and GCKR accumulate gradually in association with triglyceride increase in metabolic syndrome patients.

The common functional variants of the apolipoprotein A5 (APOA5) and the glucokinase regulatory protein genes (GCKR) have been shown to associate with increased fasting triglyceride (TG) levels. Albeit the basic association has been extensively investigated in several populations of different origin, less is known about quantitative traits of them. In our study accumulation rates of four APOA5 (T-1131, IVS3 + G476A, T1259C and C56G) and two GCKR (C1337T and rs780094) functional SNPs were analyzed in patients stratified into four TG quartile groups. Randomly selected 325 metabolic syndrome patients were separated into four quartile (q) groups based on the TG levels as follows q1: TG <1.38 mmol/l; q2: 1.38-1.93 mmol/l; q3: 1.94-2.83 mmol/l; and q4: TG >2.83 mmol/l. We observed significant stepwise increase of prevalence rates of minor allele frequencies in the four plasma TG quartiles for three APOA5 SNPs: -1131C (q1: 4.94%; q2: 8.64%; q3: 11.6%; q4: 12.3%), IVS3 + 476A (q1: 4.32%; q2: 7.4%; q3: 10.36%; q4: 11.1%), and 1259C (q1: 4.94%; q2: 7.41%; q3: 10.4%; q4: 11.7%). The haplotype analysis revealed, that the frequency of APOA5*2 haplotype gradually increased in q2, q3 and q4 (q1: 9.87%; q2: 14.8%; q3: 18.3%; q4: 21%). The distribution of the homozygotes of the two analyzed GCKR variants resembled to the APOA5 pattern. Contrary to the hypothetically predictable linear association coming from the current knowledge about the APOA5 and GCKR functions, the findings presented here revealed a unique, TG raise dependent gradual accumulation of the functional variants of in MS patients. Thus, the findings of the current study serve indirect evidence for the existence of rare APOA5 and GCKR haplotypes in metabolic syndrome patients with higher TG levels, which contribute to the complex lipid metabolism alteration in this disease.

Stepwise positive association between APOA5 minor allele frequencies and increasing plasma triglyceride quartiles in random patients with hypertriglyceridemia of unclarified origin.

Apolipoprotein A5 (ApoA5) gene and its protein product play a central role in the complex regulation of circulating triglyceride levels in humans. Naturally occurring variants of the apolipoprotein A5 gene have been associated with increased triglyceride levels and have been found to confer risk for cardiovascular diseases. In our study, four polymorphisms, the T-1131C, IVS3+G476A, T1259C, and C56G alleles of APOA5 were analyzed in a total of 436 patients by polymerase chain reaction-restriction fragment length polymorphism methods. The randomly selected patients were classified into four quartile (q) groups based on triglyceride levels (q1: TG<1.31 mmol/l; q2: 1.31-2.90 mmol/l; q3: 2.91-4.85 mmol/l; q4: TG>4.85 mmol/l). We observed significant stepwise increasing association between the four APOA5 minor allele carrier frequencies and plasma triglyceride quartiles: -1131C (q1: 4.44%; q2: 8.95%; q3: 12.9%; q4: 20.6%), IVS3 + 476A (q1: 4.44%; q2: 5.79%; q3: 11.1%; q4: 19.7%), 1259C (q1: 4.44%; q2: 6.84%; q3: 11.1%; q4: 20.6%) and 56G (q1: 5.64%; q2: 6.31%; q3: 11.16%; q4: 11.9%). The serum total cholesterol and high density lipoprotein-cholesterol levels also showed allele-dependent differences in the quartiles. The findings presented here revealed a special arrangement of APOA5 minor alleles in patients with different serum triglyceride ranges in Hungarians.

Functional variants of glucokinase regulatory protein and apolipoprotein A5 genes in ischemic stroke.

Both the natural variants of the apolipoprotein A5 (APOA5) and the glucokinase regulatory protein gene (GCKR) have been shown to associate with increased fasting triglyceride levels. Here, we investigated the possible association of the functional variants of these two genes with non-fasting triglyceride levels and their susceptibility nature in ischemic stroke. A total of 513 stroke patients and 172 healthy controls were genotyped. All the APOA5 variants (T-1131C, IVS3 + G476A, C56G, and T1259C) were associated with increased triglyceride levels in all stroke patients and controls; except for T1259C, they all conferred risk for the disease. No such association was found for the examined GCKR rs1260326 (C1337T) variant. Furthermore, we examined the effects of specific combinations of the GCKR rs1260326 and APOA5 polymorphisms. Our findings confirmed the previous results regarding the association of APOA5 variants with triglyceride-level increase and stroke susceptibility of these alleles. By contrast, we could not detect any association of the studied GCKR allele with triglyceride levels or with the susceptibility of stroke in the same cohort of patients. In addition, the effect of APOA5 did not change significantly when specific combinations of the two genes were present.