This article is more than 5 years old. Information may no longer be current.

Study suggests link between genetic factors, podoconiosis

Researchers conducting a study of patients in Ethiopia with podoconiosis, a noncommunicable lymphedema that results from walking barefoot on red clay, found a link between the disease and human leukocyte antigen class II variants.

The study included a cohort of 194 patients with podoconiosis and a control of 203 older individuals (average age 62 years vs. 24 years) with long-term barefoot exposure to red-clay soil derived from volcanic rock but no evidence of the disease.

Podoconiosis, or endemic nonfilarial elephantiasis, affects several million people in tropical regions of Africa, India, Central America, and South America. The disease causes swelling in the lower legs and mossy lesions that cover various parts of the foot.

Investigators said 5% of the population in southern Ethiopia, where the study was conducted, develops podoconiosis as a result of irritant minerals in the soil that become embedded in the feet. This triggers an immune response by macrophages in the lower limb lymphatic system.

The investigators hypothesized that this response occurs only in patients with certain human leukocyte antigen (HLA) class II variants. All participants contributed 2-mL samples of saliva for genotyping; the samples of 94 patients and 94 controls were then submitted for Luminex xMAP high-definition processing.

Study results indicated a connection between podoconiosis and the HLA class II regions that contain the specific variants HLA-DQA1, HLA-DQB1, and HLA-DRB1.

“The association of HLA class II suggests that podoconiosis is a T-cell–mediated inflammatory disease,” researchers concluded. They recommended additional studies with larger patient populations.