Association Of The Peptidase D Gene Rs731839 Polymorphism And Serum Lipid Levels In The Guangxi Mulao Population

Background:A newly genome-wide association study (GWAS) has displayed the association of the peptidase D (PEPD) gene rs731839 single nucleotide polymorphism (SNP) and lipid traits in the individuals of European ancestry. But the genetic variation has different magnitudes of effects in the different ethnicities. The present study was carried out to detect the association of the PEPD rs731839 SNP and serum lipid levels in the Guangxi Mulao and Han populations.Methods:Totals of 751 subjects of Mulao and 762 subjects of Han Chinese who settled in the Luocheng Mulao Autonomous Country, Guangxi Zhuang Autonomous Region were randomly selected from our previous stratified (age and sex) randomized samples. The epidemiological investigation was carried out following internationally standardized methods. Basic epidemiologic information was collected with standardized questionnaire from all participants. Blood samples were collected after a 12-hour fast for measurement of biochemical parameters and isolation of genomic DNA. Genotyping of the PEPD rs731839 SNP was performed using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). And then the results were verified by direct sequencing.Results:Mualo had significantly lower levels of body weight, body mass index (BMI) and diastolic blood pressure than Han (P< 0.05-0.001), whereas the levels of apolipoprotein (Apo) B and the percentages of individuals who smoked cigarettes in Mulao were markedly higher than in Han (P< 0.05 for both). The frequencies of G and A alleles were 63.8% and 36.2% in Mulao; and 63.3% and 36.7% in Han (P> 0.05); respectively. The frequencies of GG, GA and AA genotypes were 41.9%,43.8% and 14.3% in Mulao; and 39.9%,46.9% and 13.2% in Han. No significant difference was detected in either genotypic or allelic frequencies of the PEPD rs731839 SNP between Mulao and Han (P> 0.05 for both). The genotypic frequencies in Mulao males were different from Mulao females (43.0%,46.0%,11.0% vs 40.9%,41.7%,17.4%; P< 0.05). The A allele carriers had higher serum high-density lipoprotein cholesterol (HDL-C), ApoAI levels and lower triglyceride (TG) levels in Mulao; and higher HDL-C, low-density lipoprotein cholesterol (LDL-C) and ApoAI levels in Han than the A allele non-carriers (P< 0.05-0.001). According to the subgroup analyses, we concluded that the A allele carriers had higher HDL-C, ApoAI levels and lower TG levels in Mulao males but not in females (P< 0.05-0.01); higher total cholesterol (TC), HDL-C, LDL-C and ApoAI levels in Han males; and higher TG, HDL-C and ApoAI levels in Han females than the A allele non-carriers (P < 0.05 for all). The levels of serum HDL-C and ApoAI were correlated with genotypes in both Mulao and Han population. Serum lipid parameters were also correlated with several environmental factors (age, sex, alcohol consumption, cigarette smoking, etc.) in Mulao and Han populations, or in males and females in both ethnic groups (P< 0.05-0.001 for all).Conclusions:The association of the PEPD rs731839 SNP and serum lipid levels was different between the Mulao and Han populations, and between males and females in the both ethnic groups. There may be an ethnic- and/or sex-specific association of the PEPD rs731839 SNP and serum lipid levels in our study populations.