Objective: It has been suggested that genotypic variation in the gene which encodes the matrilin-1 (MATN-1) protein may be involved in the development of hip osteoarthritis (OA). We compared genotype frequencies of the MATN-1 gene (1p35) in patients with OA and controls to determine if there is any association between the MATN-1 genotype and OA.
Methods: 73 OA patients and 53 controls from a rheumatology ambulatory center and a university hospital were studied. They were unrelated subjects. Controls were free of clinical OA. OA was defined according to the American College of Rheumatology criteria. The MATN-1 microsatellite in the 3'untranslated region was amplified by PCR. The size of the amplification products was determined by capilar electrophoresis in a DNA Genetic Analizer Genotypic distribution was compared by the chi2 test.
Results: We identified 4 alleles according to their basepair (bp) length: A1 = 110 bp; A2 = 108 bp; A3 = 106 bp and A6 = 104 pb. Six genotypes were found, with an observed heterozygosity of 0.48. The most frequent genotype in OA and controls was A1/A1 (43.8% and 43.4%, respectively). No significant difference in genotype distribution was found between OA - even when discriminating by the affected joint - and controls.
Conclusion: We did not find any difference in the MATN-1 genotype distribution in OA patients and controls. To our knowledge, this would be the first time a MATN-1 allele of 104 bp (A6) has been identified These results do not support a role of the MATN-1 genotypes in the occurrence of clinical OA.