Total deficiency of plasma cholesteryl ester transfer protein in subjects homozygous and heterozygous for the intron 14 splicing defect.

The molecular basis of cholesteryl ester transfer protein (CETP) deficiency was investigated in 4 unrelated CETP-deficient families. The high density lipoprotein-cholesterol levels of the probands exceeded 150 mg/dl. The plasma of the probands was totally deficient in CETP activity and mass. The genomic DNA of the patients was amplified by polymerase chain reaction, using two oligonucleotide primers located in the intron 12 and 14 of the CETP gene, and the amplified products were directly sequenced. Two patients were homozygous for a G-to-A change at the 5'-splice donor site of the intron 14. The G-to-A change would cause impaired splicing of pre-messenger RNA. The other two probands were heterozygous for the mutation, but totally lacked CETP. Their lipoprotein patterns were also similar to those of the two homozygotes. Thus, other genetic defects or metabolic factors influencing CETP expression are implicated. The data suggest that the G-to-A mutation may be common in human plasma CETP deficiency. Furthermore, there could be compound heterozygotes who totally lack plasma CETP and have lipoprotein profiles similar to those of homozygotes.