SAT-082 Severe Hypertriglyceridemia Associated with a PRKAA1 Gene Mutation Coding for the Alpha1-Subunit of AMPK

Abstract

Background: AMP-activated protein kinase (AMPK) is implicated in several aspects of lipid metabolism including the suppression of de novo lipogenesis, promotion of fatty acid oxidation, and regulation of adipose tissue biology. We report a patient with severe hypertriglyceridemia harboring a heterozygous mutation in the PRKAA1 gene which codes for the α1-subunit of AMPK. Clinical case: A 22-year-old Mexican woman with history of morbid obesity and T2DM presented with eruptive xanthomas in the upper and lower extremities, back, and chest. VS:141/80, P 86, RR 20, 122 kg BMI 43.42 kg/m2. She was misdiagnosed on multiple occasions and had been treated with steroids until a biopsy revealed foamy histiocytes consistent with xanthomas. A lipid panel showed Triglycerides 8,513 mg/dl (0-150 mg/dl) Cholesterol 555 mg/dl (0-199 mg/dl) HDL 29 mg/dl (≥ 41 mg/dl) Direct LDL 44 (0-99). There was no family history of hyperlipidemia. After ~24-months of follow-up abnormal lipid levels persisted: Triglycerides 4527-8513 mg/dl (0-150 mg/dl) Cholesterol 408-555 mg/dl (0-199 mg/dl) HDL 22-29 mg/dl (≥ 41 mg/dl). She had microalbuminuria 87.7 mcg/mg (0-29.9 mcg/mg) and an HbA1c of 7.8%. She endorsed depression and was inconsistent with her diet due to insatiable appetite but reported medication compliance. Lipoprotein electrophoresis showed a pattern consistent with type IV Hyperlipoproteinemia. Sequencing of lipid metabolism genes revealed no abnormalities but upon whole exome scanning she was found to have a heterozygous nonsense variant in PRKAA1 (exon4:c.C394T:p.Q132X) which codes for the α1-subunit of AMPK resulting in a premature stop codon. We hypothesize that this variant results in defective AMPK activity, and given the role of AMPK in lipid and adipose tissue metabolism, it may result in disinhibition of lipogenesis, reduced fatty acid oxidation, and altered adipose tissue biology, together promoting extreme hypertriglyceridemia. Conclusion: This is the first case to implicate a PRKAA1 gene mutation as a cause of severe hypertriglyceridemia in humans.