Association of Adam 12 variants with osteoarthritis in an urban South African population

Abstract

Background: Osteoarthritis (OA) is a multifactorial, progressive, and degenerative disease of the synovial joints. A disintegrin and metalloproteinase domain 12 (ADAM12) gene variants have been associated with OA in Asians and Europeans, but not in the African populations. We therefore examined the association of OA with ADAM12 gene variants rs1278279, rs3740199, rs1044122 and rs1871054 in the South African population.
Methods: A cross-sectional, case-control study was conducted amongst 377 South Africans, consisting of 136 OA cases and 241 non-OA controls.  A questionnaire was used to collect demographic data. Anthropometry variables were measured using standard methods. DNA samples were genotyped using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. (MALDI-TOF MS.) The standard models of genetic association were used to evaluate the effect of ADAM12 variants on OA risk. A multivariate test using logistic regression was conducted on selected variants while adjusting for age, sex and BMI.
Results: A unit increase in body mass index (BMI) increased the likelihood of OA among black (odds ration[OR] = 1.12 times; p<0.001) and white (OR = 1.13 times; p= 0.026) participants. A unit increase in age increased the likelihood of OA by 1.10 times (p<0.001) among black participants. Also, the male gender was significantly associated with reduced risk of OA (OR= 0.42; p=0.010) among black participants. Of the four ADAM12 variants, rs1871054 was associated with an increase in OA risk among white South Africans participants, before (p=0.008) and after (p=0.036), adjusting for age, gender and BMI only.
Conclusion: The findings of this study suggest the need for ethnic-specific variants to assess the genetic susceptibility of OA among the black South African population.