Cryptogenic cirrhosis in a patient with familial hypocholesterolemia due to a new truncated form of apolipoprotein B

Abstract

Familial hypobetalipoproteinemia (FHBL) is an autosomal codominantly inherited disorder of lipoprotein metabolism characterized by decreased concentrations of low-density lipoprotein-cholesterol and of apolipoprotein B (apoB). Mutations of APOB gene lead to the formation of truncated forms of apoB. The study aimed at determining the truncated form of apoB responsible for FHBL associated with liver cirrhosis in a 27-year-old man. Analysis of the patient's lipoproteins has been performed by SDS-PAGE electrophoresis followed by immunoblotting with monoclonal antibodies. DNA of the family (proband, daughter, wife, father, and mother) was extracted, and PCR amplification was realized; amplicons were screened and sequenced. Electrophoresis allowed us to identify a truncated form of apoB (close to apoB 59%), associated with a new heterozygous apoB variant, 8402 C>G. This mutation creates a stop codon (TAC>TAG, Y2807X) and predicts to generate a truncated protein (apoB-61.9%). No other causes of cirrhosis were established by comprehensive clinical and biological investigations. We described here an unusual clinical observation of a patient with FHBL and early development of liver cirrhosis due to a new truncated form of apoB.