Evaluation of apolipoprotein A5 variants: A cohort of patients with severe hypertriglyceridemia from Turkiye

• Published in: Journal of clinical lipidology 2024-05, Vol.18 (3), p.e423-e429
• Main Authors: Cakmak, B., Yeral, S., Ozcan, B., Pariltay, E., Ozgul, S., Simsir, I.Y., Hegele, R.A.
• Format: Article
• Language: English
• Subjects: Apolipoprotein A-V; Hypertriglyceridemia; Obesity; Overweight; Pancreatitis
• ISSN: 1933-2874; 1876-4789
• DOI: 10.1016/j.jacl.2023.09.015

•Hypertriglyceridemia is a common biochemical phenotype that affects about 5 % of adults.•Polygenic hypertriglyceridemia is the most common cause of hypertriglyceridemia.•Apo A-V is a triglyceride modulator that hydrolyzes triglyceride-rich lipoproteins.•Heterozygous mutations of APOA5 do not directly cause severe hypertriglyceridemia. This study aims to show the clinical and biochemical features in patients with severe hypertriglyceridemia (HTG) associated with rare variants in the apolipoprotein A-V (APOA5) gene. Demographics, blood lipid levels, body mass index (BMI) and APOA5 mutation subtypes were collected from the endocrinology clinic registry and analyzed for a retrospective cohort study of ten patients with severe HTG and APOA5 gene variants. Of the 10 cases, four were female, and six were male. The median age was 45.0 years (min-max: 21–60 years), the median triglyceride was 2429.5 mg/dL (27.5 mmol/L) (min-max: 1351–4087 mg/dL, 15.3–46.2 mmol/L), and the mean BMI was calculated as 30.4 ± 4.4 kg/m2 (min-max: 24.9–41.0 kg/m2). Four cases had diabetes mellitus (DM); two were on intensive insulin therapy, and two were on basal insulin therapy. The mean hemoglobin A1c was 9.2 ± 1.2 % (min-max: 8.3–11.0 %). Among the study group, eight different APOA5 gene mutations were detected. These variants were heterozygous in 2 patients and homozygous (bi-allelic) in 8 patients. One patient was homozygous for APOA5 p.Ser19Trp, a relatively common polymorphism that is a risk variant for HTG. We report a cohort of patients with biallelic and single copy APOA5 variants, who were diagnosed later in life. Most had secondary factors, such as DM or obesity with increased BMI. Most rare APOA5 variants found in our patients were of uncertain significance. Our results add to the growing evidence that rare variants in certain candidate genes may predispose to developing HTG, together with secondary factors such as obesity. The genetic basis of HTG in many other patients is still unknown and remains the subject of further investigation.