(HealthDay News) – Genetic variants in the HLA class II region are associated with podoconiosis, a tropical lymphedema resulting from long-term barefoot exposure to soil derived from volcanic rock.

Fasil Tekola Ayele, PhD, MPH, of the National Human Genome Research Institute in Bethesda, MD, and colleagues conducted a genome-wide association study of 194 case patients and 203 controls from southern Ethiopia. Findings were validated by family-based association testing in 202 family trios and HLA typing in 94 case patients and 94 controls.

The researchers found that there was a significant genome-wide association between podoconiosis with the single nucleotide polymorphism (SNP) rs17612858, located 5.8kb from the HLA-DQA1 locus (in the allelic model: odds ratio [OR], 2.44; in the additive model: OR, 2.19) and suggestive significant associations with seven other SNPs in or near HLA-DQB1, HLA-DQA1, and HLA-DRB1. These associations were confirmed using family-based association testing. HLA typing showed that the alleles HLA-DRB1*0701 (OR, 2.00), DQA1*0201 (OR, 1.91), and DQB1*0202 (OR, 1.79) and the HLA-DRB1*07017-DQB1*0202 haplotype (OR, 1.92) were risk variants for podoconiosis.

“Association between variants in HLA class II loci with podoconiosis (a noncommunicable disease) suggests that the condition may be a T-cell-mediated inflammatory disease and is a model for gene-environment interactions that may be relevant to other complex genetic disorders,” the authors write.

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