Identifying new associated pleiotropic SNPs with lipids by simultaneous test of multiple longitudinal traits: An Iranian family-based study.

A number of genome-wide association studies (GWASs) have identified several genetic determinants of plasma lipids in European populations, in which analytical approaches have often been based on the linear regression models and the association test between a SNP and each lipid component individually in cross-sectional designs. Since lipid variations are correlated, the consideration of pleiotropy is necessary and using methods that can perform simultaneous association test of multiple longitudinal traits provides more information about the recognition of the pleiotropic variants. To identify new pleiotropic variants and to determine whether loci identified in previous GWASs can also exert the same effect on lipid concentrations in Iranian population, longitudinal measurements of lipid variations were used in a sample of Iranian population (16,353 individuals within 3100 families) that followed up every 3 years and using a two-step model, the associations of 20,036 available SNPs on chromosome 16 were assessed. Twenty variants within the AC009035.1, SLC12A3, CETP, NLRC5, ESRP2 and, C16orf95 genes showed strong evidence for association with HDL-C, cholesterol, and triglycerides with p-values ranging from 1.7 × 10 to 6.6 × 10. Since many genetic variants associated with lipids still remain to be determined, the results of the present study may provide valuable information on identifying the associations of new genetic loci with lipid variations in other populations.