A missense mutation (Ala334-->Thr) in exon 7 of the lipoprotein lipase gene in a case with type I hyperlipidemia.

The patient is a 34-year-old female. Her fasting plasma triglyceride and cholesterol levels were 7523 mg/dl and 818 mg/dl, respectively, at 35 weeks' gestation. The lipoprotein lipase (LPL) activity and mass from postheparin plasma of the proband were 0.02 (normal range: 5.51 +/- 1.12 mu mol/ml/h) and 168 ng/ml (normal range: 220 +/- 42 ng/ml), respectively, indicating that the LPL of the patient would be functionally defective LPL. DNA sequence analysis of the LPL gene from the patient revealed a homozygous nucleotide change: a G--> A transition at nucleotide position of 1255 resulting in an amino acid substitution of Thr for Ala 334. This is the first natural missense mutation identified in exon 7 of the LPL gene.