Genetic variation of NEDD4L is associated with essential hypertension in female Kazakh general population: a case-control study

Background: Hypertension affects > 18.8% of adults in China. Indeed, hypertension is the most prevalent risk factor for cardiovascular morbidity and mortality worldwide. Genetic variation is thought to contribute to the etiology of hypertension. NEDD4L is a candidate gene for hypertension, both functionally and genetically. The purpose of the current study was to investigate the relationship between the variation in NEDD4L and essential hypertension in Kazakh, which is a relatively isolated population with a pure genetic background and is an ideal population to study genetic mechanisms of hypertension. Methods: We screened the promoter and exons of NEDD4L in 94 Kazakh hypertensive individuals to identify representative variations. Then, by genotyping the representative variations in the Kazakh general population, a case-control study was conducted. Results: By systemically screening variations of NEDD4L, we did not identify any functional mutations in NEDD4L. A new common variation (296921-296923delTTG), which is not found in the NCBI database, was identified. Three representative variations (296921-296923delTTG, rs2288774, and rs2288775) were successfully genotyped in the Kazakh general population. The distribution of the dominant model (AA vs. AG+GG) of rs2288775, the additive model, and the recessive model (II+ID vs. DD) of 296921-296923delTTG differed significantly between the casesand controls in females (P=0.040, P=0.024, and P=0.007, respectively). After adjusting for confounding factors, logistic regression analysis showed that rs2288775 (in the dominant model) and 296921-296923delTTG (in the recessive model) were significantly associated with hypertension (rs2288775: OR=1.479, 95% CI=1.011-2.064, p=0.044; and 296921-296923delTTG: OR=1.908, 95% CI=1.020-3.568, p=0.043) in females. The frequency of the DCG haplotype was significantly higher for cases than for controls in females (P=0.020). There was a significant interaction between the NEDD4L genotype and gender (P for interaction: 0.045 for rs2288775 and 0.064 for 296921-296923delTTG), but there was no significant interaction between the NEDD4L genotype and smoking (P for interaction: 0.616 for rs2288775 and 0.447 for 296921-296923delTTG). For females and total participants, the urinary Na excretion rate was significantly lower in the DD than the I/I+I/D individuals (P=0.032 and P=0.027 respectively). Conclusion: The genetic variations of NEDD4L may be associated with essential hypertension in females in the Kazakh general population.