Focused panel sequencing points to genetic predisposition in non-cirrhotic intrahepatic portal hypertension patients in India.

Objective: Non-cirrhotic intrahepatic portal hypertension (NCIPH), a portal microangiopathy affecting small portal vein radicles, is a disease of Indian sub-continent. NCIPH appears to be a complex disease with interactions between inherited and acquired factors, though the exact pathophysiological mechanism is unknown. We aimed at investigating the genetic variants that might contribute to susceptibility to NCIPH.

Methods: In this case-control study, we analyzed genes associated with microangiopathy-VWF-ADAMTS13 (von Willebrand factor and its cleavase enzyme - a disintegrin and matrix metalloprotease with thrombospondin type-1 motifs member 13) and alternative complement system vitamin B metabolism and with familial NCIPH.

Result: Eighty-four Indian patients with liver biopsy-proven NCIPH (cases) and 103 healthy controls (matched for residential region of India) were included in the study. Targeted next-generation sequencing (NGS) panel, comprising 11 genes of interest, was done on 54 cases. Genotyping of selected variants was performed in 84 cases and 103 healthy controls. We identified variants in MBL2, CD46 and VWF genes either associated or predisposing to NCIPH. We also identified a single case with a novel compound heterozygous mutation in MBL2 gene, possibly contributing to development of NCIPH.

Conclusion: In this first of a kind comprehensive gene panel study, multiple variants of significance have been noted, especially in ADAMTS13-VWF and complement pathways in NCIPH patients in India. Functional significance of these variants needs to be further studied.