Increasing the Sensitivity of Single-Strand Conformation Polymorphism Analysis of the LDLR Gene Mutations in Brazilian Patients with Familial Hypercholesterolemia

Abstract

Mutations in the low-density lipoprotein receptor (LDLR) gene cause familial hypercholesterolemia (FH), one of the most common single gene disorders. It is thought that FH affects approximately 1 of 500 individuals in most populations. Single-strand conformation polymorphism (SSCP) analysis is widely used to detect mutations in the LDLR gene. However, several factors such as temperature, pH, running time, gel composition and size of the DNA fragments can influence its sensitivity. We have optimized the electrophoretic conditions to screen mutations in the promoter region and exons 1–18 of the LDLR gene by varying temperature (5 °C, 8 °C, 12 °C and 15 °C), voltage (300 to 600 V), and running time (1 to 4 hours) in the semi-automated GenePhor™ system (Amersham Biosciences). The efficiency of the method was evaluated by using 30 positive controls (DNA samples with mutations and polymorphisms in the LDLR gene, previously characterized) and DNA samples from 90 Brazilian patients with FH. Our results show that the use of two temperatures (5 °C and 15 °C) in combination with other optimized conditions resulted in high mutation detection rate (97%), which was considered appropriate for routine screening. Therefore, this strategy could be useful for the diagnosis of genetic disorders, cancer, and for pharmacogenetic studies.