OBJECTIVETo identify the mutation of low density lipoprotein receptor(LDLR) gene in a large Chinese family with familial hypercholesterolemia(F H) and make a discussion on the pathogenesis of FH at the molecular level.

METHODSInvestigations were made on a patient with the clinical phenotype of homozygous FH and his parents for mutations of promoter and all 18 exons of LDLR gene. Screening was carried out using Touch down PCR and a g arose gel electrophoresis, combined with DNA sequence analysis. The results were compared with the normal sequences in GenBank and FH database (www.ucl.uk/fh) t o find the mutation. Then the mutation was identified in other members of the family. In addition, the authors screened the apolipoprotein B(100) (apoB(100)) gene f or known mutations (R3500Q) that cause familial defective apoB(100) (FDB) by PCR-RFLP.

RESULTSA novel homozygous IN III 5' GT --> AT mutation in the splice donor of LDLR intron 3 was detected in the homozygote propositus with FH. The mutation was also identified in four heterozygous carriers in his family. No mutations R3500Q of apoB(100)were observed.

CONCLUSIONA homozygous G --> A splice mutation in LDLR gene was first reported. The change of the splice donor in LDLR intron 3 may cause skipping of exon 3, which is responsible for FH. Perhaps it is a particular pathogenesis for Chinese people.