1 Department of Core Clinical Pathology and Biochemistry, PathWest Laboratory Medicine WA;
2 School of Surgery and Pathology;
3 School of Medicine and Pharmacology, University of Western Australia, Royal Perth Hospital, GPO Box X2213, Perth, WA 6847, Australia
Corresponding author: Dr John R Burnett, Department of Core Clinical Pathology and Biochemistry, PathWest Laboratory Medicine WA, Royal Perth Hospital, GPO Box X2213, Perth, WA 6847, Australia. Email: john.burnett{at}health.wa.gov.au
Lipoprotein lipase (LPL) is the key enzyme in the catabolism of triglyceride-rich lipoproteins in the circulation. Familial LPL deficiency is characterized by hypertriglyceridaemia and absence of LPL activity. We report a case of LPL deficiency in a 43-year-old woman, who initially presented in childhood with chylomicronaemia syndrome. At that time, her plasma triglyceride concentration was
30 mmol/L and post-heparin lipolytic activity was very low. In addition to having the known missense mutation LPL G188E, the patient was also found to have a novel nonsense mutation in exon 8, namely LPL W394X. The novel substitution in exon 8 (c.1262G > A) predicts a truncated protein product of 393 amino acids that lacks the carboxyl-terminal 12% of the mature LPL. Trp394 is part of a cluster of exposed tryptophan residues in the carboxyl-terminal domain of LPL important for binding lipid substrate. Of 11 members from her three-generation family, three were heterozygotes for G188E (mean plasma triglyceride, 3.5 ± 2.0 mmol/L), whereas six were heterozygotes for W394X (triglyceride, 4.3 ± 1.8 mmol/L). In summary, we describe a case of familial LPL deficiency caused by compound heterozygosity for known (G188E) and novel (W394X) LPL gene mutations.
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