Association between C677T/MTHFR genotype and homocysteine concentration in a Kazakh population

We recently suggested that due to insufficient intake of vegetables, low folate status and mild homocysteinemia might exist in the Kazakh population. To clarify the determinants of homocysteine concentrations among this population, we determined concentrations of serum folate, albumin, creatinine, vitamin B12, and the C677T/ MTHFR genotype in 110 Kazakh individuals and compared these with plasma total homocysteine. In Kazakh, after adjustment for age and sex, folate was correlated with plasma total homocysteine, whereas concentrations in those with the TT genotype was almost twice as high as in those with the CC and CT genotypes (19.7+/-1.8 micromol/L vs. 10.7+/-0.5 micromol/L, p<0.001). Our results suggest that the C677T/MTHFR genotype is associated with homocysteine concentrations in this population and this association might be affected by other factors, such as folate status.     

Development of the Kazakhstan Y-chromosome haplotype reference database: analysis of 27 Y-STR in Kazakh population

To improve available databases of forensic interest, all Y-STR haplotypes from Kazakh population were presented in this study. The reference database accumulated almost 3650 samples from academic and citizen science. Additionally, 27 Y-STR from Yfiler Plus System were first analyzed in 300 males from Kazakh (Qazaq) populations residing in Kazakhstan. The data is available in the YHDR under accession numbers YA004316 and YA004322. A total of 270 unique haplotypes were observed. Discrimination capacity was 90%. Obtained Y-STR haplotypes exhibited a high intra-population diversity. Analysis of pairwise genetic distances showed lowest R_ST values from Uighur and Mongolian populations.

     

Mitochondrial and Y-chromosomal profile of the Kazakh population from East Kazakhstan

Aim

To study the genetic relationship of Kazakhs from East Kazakhstan to other Eurasian populations by examining paternal and maternal DNA lineages.

Methods

Whole blood samples were collected in 2010 from 160 unrelated healthy Kazakhs residing in East Kazakhstan. Genomic DNA was extracted with Wizard® genomic DNA Purification Kit. Nucleotide sequence of hypervariable segment I of mitochondrial DNA (mtDNA) was determined and analyzed. Seventeen Y-short tandem repeat (STR) loci were studied in 67 samples with the AmpFiSTR Y-filer PCR Amplification Kit. In addition, mtDNA data for 2701 individuals and Y-STR data for 677 individuals were retrieved from the literature for comparison.

Results

There was a high degree of genetic differentiation on the level of mitochondrial DNA. The majority of maternal lineages belonged to haplogroups common in Central Asia. In contrast, Y-STR data showed very low genetic diversity, with the relative frequency of the predominant haplotype of 0.612.

Conclusion

The results revealed different migration patterns in the population sample, showing there had been more migration among women. mtDNA genetic diversity in this population was equivalent to that in other Central Asian populations. Genetic evidence suggests the existence of a single paternal founder lineage in the population of East Kazakhstan, which is consistent with verbal genealogical data of the local tribes.In terms of population genetics, Central Asia is one of the least studied regions in the world. The studies conducted in the region, based on scarce genetic data, indicate that the Central Asia population is a mix of Eastern and Western populations (1,2). Kazakhstan is a vast country, which has throughout history been inhabited by different nomadic tribes such as the Argyn, Dughlat, Jalayir, Kerei, Kipchak, Madjar, Naiman, and others (3). The Kazakh ethnic group was formed in the 15th century under a huge infulence of the Mongol Empire (4). We expected the genetic profile of Kazakhs to be heterogeneous because of the different tribes and ethnicities (5).The current study focused on the Kazakh population of the East Kazakhstan Province, because recently there have been many reports on the neighboring populations of Xinjiang Uyghur Autonomous Region and Altai regions. East Kazakhstan is populated by the Naiman tribe. Their genealogical narrative, “shezhire,” states that the Naiman people living in Tarbagatay region are descendants of one ancestor, named Toktar-kozha, who came from the territory of modern Uzbekistan and was a Sart by origin. Based on the data from “shezhire,” we formed a hypothesis of uniform paternal descent of the Naiman tribe. The aim of this study was to better understand the origins and differentiation of the Kazakh ethnic group and to investigate the genetic relationship between this population and other Eurasian populations.     

Thyroid function is associated with carotid intima-media thickness in euthyroid subjects

To investigate the relationship between thyroid function and carotid intima-media thickness (CIMT) in a relatively large general population with euthyroid status we initially enrolled 1772 Japanese adults (421 men and 1351 women) who participated in a medical screening program for the general population over 40 years old. To evaluate only euthyroid subjects without vascular diseases and/or its major risk factors, 1129 were excluded and 643 participants (175 men and 468 women) were included for further analysis. Simple and multivariate linear regression analyses were performed to evaluate free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels and other existing parameters, including carotid intima-media thickness. By multivariate linear regression analysis adjusted for age and sex, free thyroxine was significantly correlated with triglycerides (beta=0.07, p=0.015), carotid intima-media thickness (beta=-0.091, p=0.049), and thyroid-stimulating hormone (beta=-0.091, p=0.003). Thyroid-stimulating hormone was significantly correlated with high-density lipoprotein cholesterol (HDL-C) (beta=-0.001, p=0.015), HbA(1c) (beta=0.038, p=0.045), carotid intima-media thickness (beta=0.27, p=0.001), and free thyroxine (beta=-0.15, p=0.003). When adjusted for confounding factors, free thyroxine was significantly correlated only with carotid intima-media thickness (beta=-0.13, p=0.043) and thyroid-stimulating hormone was significantly correlated with HDL-C (beta=-0.001, p<0.001), HbA(1c) (beta=0.04, p=0.021), and carotid intima-media thickness (beta=0.29, p=0.001). We have demonstrated that carotid intima-media thickness is independently associated with thyroid function within the normal reference range, which suggests an increased cardiovascular risk in subjects with low normal thyroid function.     

Kazakhstan: a folate-deficient area?

OBJECTIVE: In the Republic of Kazakhstan, located in central Asia, the traditional diet consists mainly of meat, and vegetable intake tends to be deficient. This eating lifestyle may contribute to folate deficiency, which is closely linked to abnormal homocysteine (HCY) metabolism. SUBJECTS AND METHODS: In order to evaluate current folate status in the healthy Kazakh population, we screened serum folate and plasma HCY in 50 healthy Kazakh adults aged 20-65 years (KZH) and 60 healthy Japanese control subjects aged 27-65 years (JPN). RESULTS: Serum levels of folate were significantly lower in KZH than in JPN (3.1 vs 10.0 ng/ml, P<0.01). Fifty of 61 (82.0%) subjects in KZH but none in JPN showed low concentrations of folate (<3.6 ng/ml). Plasma levels of HCY were significantly higher in KZH than in JPN (13.2 vs 7.8 nmol/ml, P<0.01). CONCLUSIONS: Our findings strongly suggest that owing to the insufficient intake of vegetables, folate deficiency exists in Kazakhstan. Furthermore, hyperhomocysteinemia was observed in this group, probably owing to the secondary effects of folate deficiency.