Novel α-1,3-Glucosyltransferase Variants and Their Broad Clinical Polycystic Liver Disease Spectrum

Abstract

Protein-truncating variants in α-1,3-glucosyltransferase (ALG8) are a risk factor for a mild cystic kidney disease phenotype. The association between these variants and liver cysts is limited. We aim to identify pathogenic ALG8 variants in our cohort of autosomal dominant polycystic liver disease (ADPLD) individuals. In order to fine-map the phenotypical spectrum of pathogenic ALG8 variant carriers, we performed targeted ALG8 screening in 478 ADPLD singletons, and exome sequencing in 48 singletons and 4 patients from two large ADPLD families. Eight novel and one previously reported pathogenic variant in ALG8 were discovered in sixteen patients. The ALG8 clinical phenotype ranges from mild to severe polycystic liver disease, and from innumerable small to multiple large hepatic cysts. The presence of ALG8-associated ADPLD has a broad clinical spectrum, including the possibility of developing a small number of renal cysts. This broadens the ADPLD genotype–phenotype spectrum and narrows the gap between liver-specific ADPLD and kidney-specific ADPKD.

Keywords

• ADPLD
• ALG8
• clinical spectrum
• next-generation sequencing
• polycystic liver disease