CASE-REPORT Association between an ACAN gene variable number tandem repeat polymorphism and lumbar disc herniation: a case control study.
We investigated the association between an aggrecan gene (ACAN) polymorphism and lumbar disc herniation (LDH). This was a case-control study with quinquennial age and gender groups. The study comprised 119 men and women aged between 20 and 60 from Goiânia (Brazil). Of these, 39 were allocated to the case group (Ca) and 80 to the control group (Ct). We gathered sociodemographic and clinical data, and peripheral blood samples. DNA was isolated for genotyping the ACAN variable number tandem repeat (VNTR) via conventional polymerase chain reaction (PCR). Data were statistically analyzed using the chi-square test, multiple comparison analysis, the Student t-test, and odds ratios, with a level of significance set at 5% (P ≤ 0.05). The groups were homogenous in terms of sociodemographic, anthropometric, and life style variables. The allele score for the ACAN VNTR was significantly lower in volunteers with LDH; the A22 allele was significantly more prevalent in this same group; the Ca group presented greater frequency of short alleles A13-A25, whereas the Ct group presented a higher frequency of long alleles. However, this difference was not statistically significant. In both groups, the most common alleles were A28, A27, and A29, and the A26/A26 genotype was significantly more common in the Ca group. The results showed an association between short alleles and LDH among the investigated adults (Ca), corroborating the hypothesis that aggrecan with shorter repeat lengths can lead to a reduction in the physiological proteoglycan function of intervertebral disc hydration and, consequently, increased individual susceptibility to LDH.