Risk Factors Affecting the Phenotypic Expression of Heterozygous Familial Hypercholesterolemia in Pakistani Population

Abstract

Familial hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism recognized by high plasma concentrations of low-density lipoprotein cholesterol (LDL-C), tendon xanthomas, and high risk of early coronary heart disease. The phenotypic expression of FH is variable and several genetic and other risk factors contribute to such variability in clinical expression of the disease. FH is an autosomal disorder characterized by increased levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and tendinous xanthmata (TX). Clinical phenotype of FH has previously been shown to be associated with increased coronary heart disease (CHD) and premature death. The present study was carried out in a Pakistani population to examine the contribution of environmental factors on the expression of this disease. A detailed examination of the physical and biochemical features of the FH was performed in a cohort of 335 individuals (202 males, 133 females) from Pakistan. Our results indicate that Pakistani females with FH had high levels of TC and LDL-C as compared to Pakistani males. Overall the concentrations of high density lipoprotein cholesterol (HDL-C) were significantly lower for both sexes as compared to the controls (normal). We have also found that high cholesterol levels were associated with increased incidence of CHD in FH Pakistani population where both male and female individuals showed 69% and 31% CHD, respectively. The mean onset age for coronary symptoms was about 38 years in males as compared to 45 years in females. A greater risk of developing CHD has been linked with levels of TC along with a history of smoking in males and presence of hypertension (HTN) in females. Our results indicate that these risk factors possibly affect and contribute in the phenotypic expression of FH in Pakistani population.