NRG1 variant effects in patients with Hirschsprung disease

Background: Hirschsprung disease (HSCR) is a heterogeneous genetic disorder characterized by absence of ganglion cells along the intestines resulting in functional bowel obstruction. Mutations in neuregulin 1 (NRG1) gene have been implicated in some cases of intestinal aganglionosis. This study aims to investigate the contribution of the NRG1 gene to HSCR development in an Indonesian population.

Methods: We analyzed the entire coding region of the NRG1 gene in 54 histopathologically diagnosed HSCR patients.

Results: All patients were sporadic non-syndromic HSCR with 53/54 (98%) short-segment and 1/54 (2%) long-segment patients. NRG1 gene analysis identified one rare variant, c.397G > C (p.V133 L), and three common variants, rs7834206, rs3735774, and rs75155858. The p.V133 L variant was predicted to reside within a region of high mammalian conservation, overlapping with the promoter and enhancer histone marks of relevant tissues such as digestive and smooth muscle tissues and potentially altering the AP-4_2, BDP1_disc3, Egr-1_known1, Egr-1_known4, HEN1_2 transcription factor binding motifs. This p.V133 L variant was absent in 92 non-HSCR controls. Furthermore, the rs7834206 polymorphism was associated with HSCR by case-control analysis (p = 0.037).

Conclusions: This study is the first report of a NRG1 rare variant associated with HSCR patients of South-East Asian ancestry and provides further insights into the contribution of NRG1 in the molecular genetic pathogenesis of HSCR.