When is LDL Cholesterol Too Low?

Abstract

Background: Familial hypobetalipoproteinemia (FHBL) is a rare genetic disorder that causes unusually low levels of LDL-C and apolipoprotein B (apoB). There are higher incidences of FHBL in pediatric patients with fatty liver disease than the general population and they tend to have more severe hepatic steatosis. Case Presentation: A 6-year-old Caucasian male presented with his mother as a referral with an LDL-C of 25 mg/dL, well below the 5th percentile for age and sex. No pertinent past medical history is recorded. Per mother, his maternal grandfather had a history of low LDL-C with no known heart disease. Mother is well without recorded LDL-C. Father's health status in unknown. A lipid panel of the patient revealed: total cholesterol of 82 mg/dL, triglycerides (TG) of 31 mg/dL, HDL-C of 55 mg/dL and a direct LDL-C of 24 mg/dL. The patient's apoB levels was < 30 mg/dL (RR 52-109 mg/dL) and apoA1 was 134 mg/dL (RR 94-136 mg/dL). Additionally, liver function tests (LFTs) were performed: AST of 23 U/L (RR 12-32 U/L) and ALT 24 U/L (RR 8-32 U/L). APOB sequencing revealed a heterozygous mutation (c.10848delT). A lipid panel of the patient's 8-year-old brother showed a total cholesterol of 91 mg/dL, TG of 37 mg/dL, HDL-C of 54 mg/dL, and an LDL-C of 30 mg/dL. Conclusions: Follow-up recommendations for FHBL include laboratory testing of lipids and LFTs every year with clinical evaluation every 6-12 months.