W13.340 A novel non-truncating APOB gene mutation, L343V, causes familial hypobetalipoproteinaemia

Identification of novel APOB mutations by targeted next-generation sequencing for the molecular diagnosis of familial hypobetalipoproteinemia

BACKGROUND AND AIMS

Familial hypobetalipoproteinemia (FHBL) is a co-dominant disorder characterized by decreased plasma levels of LDL-cholesterol and apolipoprotein B (ApoB). Currently, genetic diagnosis in FHBL relies largely on Sanger sequencing to identify APOB and PCSK9 gene mutations and on western blotting to detect truncated ApoB species.

METHODS

Here, we applied targeted enrichment and next-generation sequencing (NGS) on a panel of three FHBL genes and two abetalipoproteinemia genes (APOB, PCSK9, ANGPTL3, MTTP and SAR1B).

RESULTS

In this study, we identified five likely pathogenic heterozygous rare variants. These include four novel nonsense mutations in APOB (p.Gln845*, p.Gln2571*, p.Cys2933* and p.Ser3718*) and a rare variant in PCSK9 (Minor Allele Frequency <0.1%). The affected family members tested were shown to be carriers, suggesting co-segregation with low LDL-C.

CONCLUSIONS

Our study further demonstrates that NGS is a reliable and practical approach for the molecular screening of FHBL-causative genes that may provide a mean for deciphering the genetic basis in FHBL.