AN EFFICIENT SCREENING-PROCEDURE DETECTING 6 NOVEL MUTATIONS IN THE LDL-RECEPTOR GENE IN SWEDISH CHILDREN WITH HYPERCHOLESTEROLEMIA

Familial hypercholesterolemia (FH) is an autosomal semi-dominant disor der caused by defects in the low density lipoprotein receptor (LDLR) g ene and is a well-documented risk factor for developing cardiovascular disease. The LDLR genes of five Swedish children with FH were examine d in this study. Initial mutation screening was performed by denaturin g gradient gel electrophoresis (DGGE) with enzymatically amplified exo n-sized fragments, each containing a tailing GC-rich requence. The GC- clamped fragments had been synthesized with a restriction site adjacen t to the intron-corresponding sequence to allow detachment of the clam ps, thereby rendering the fragments suitable for subsequent analysis b y single-strand conformation polymorphism (SSCP) analysis of samples f rom patients with no DGGE-detectable mutations. In addition, all the L DLR genes of the patients were screened for large alterations by restr iction fragment length polymorphism analysis. Following this strategy, seven different, potentially disease-causing mutations were detected in the five children with FH. Six of the alterations, five single-base substitutions and one dinucleotide deletion, have not previously been described. DGGE detected six of the mutations and SSCP the seventh.