Deep resequencing identifies candidate functional genes in leprosy GWAS loci

PLoS Negl Trop Dis. 2021 Dec 8;15(12):e0010029. doi: 10.1371/journal.pntd.0010029. eCollection 2021 Dec.

Abstract

Leprosy is the second most prevalent mycobacterial disease globally. Despite the existence of an effective therapy, leprosy incidence has consistently remained above 200,000 cases per year since 2010. Numerous host genetic factors have been identified for leprosy that contribute to the persistently high case numbers. In the past decade, genetic epidemiology approaches, including genome-wide association studies (GWAS), identified more than 30 loci contributing to leprosy susceptibility. However, GWAS loci commonly encompass multiple genes, which poses a challenge to define causal candidates for each locus. To address this problem, we hypothesized that genes contributing to leprosy susceptibility differ in their frequencies of rare protein-altering variants between cases and controls. Using deep resequencing we assessed protein-coding variants for 34 genes located in GWAS or linkage loci in 555 Vietnamese leprosy cases and 500 healthy controls. We observed 234 nonsynonymous mutations in the targeted genes. A significant depletion of protein-altering variants was detected for the IL18R1 and BCL10 genes in leprosy cases. The IL18R1 gene is clustered with IL18RAP and IL1RL1 in the leprosy GWAS locus on chromosome 2q12.1. Moreover, in a recent GWAS we identified an HLA-independent signal of association with leprosy on chromosome 6p21. Here, we report amino acid changes in the CDSN and PSORS1C2 genes depleted in leprosy cases, indicating them as candidate genes in the chromosome 6p21 locus. Our results show that deep resequencing can identify leprosy candidate susceptibility genes that had been missed by classic linkage and association approaches.

MeSH terms

  • Adolescent
  • Adult
  • B-Cell CLL-Lymphoma 10 Protein / genetics
  • Female
  • Genetic Linkage
  • Genetic Predisposition to Disease*
  • Genome-Wide Association Study*
  • High-Throughput Nucleotide Sequencing
  • Humans
  • Interleukin-18 Receptor alpha Subunit / genetics
  • Interleukin-18 Receptor beta Subunit / genetics
  • Leprosy / genetics*
  • Male
  • Young Adult

Substances

  • B-Cell CLL-Lymphoma 10 Protein
  • BCL10 protein, human
  • IL18R1 protein, human
  • IL18RAP protein, human
  • Interleukin-18 Receptor alpha Subunit
  • Interleukin-18 Receptor beta Subunit

Grants and funding

This work was supported by a Foundation grant from the Canadian Institutes of Health Research (CIHR) to ES (FDN-143332). This research was supported through resource allocation in the Cedar high performance computing cluster by Compute Canada to ES and VMF (www.computecanada.ca) / Calcul Québec (www.calculquebec.ca). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.