O alelo Trp3 do SNP rs61734651 do gene COL9A3 aumenta o risco relativo para a Hérnia de Disco Lombar em indivíduos de uma amostra populacional de Goiânia (Brasil)

Abstract

About 80% of the world population suffer from back pain. The most common causes of this pain are spinal disc herniation, which could happen anywhere along the spine, but it is most frequent at the lumbar region, known as Herniated Lumbar Disc (HLD). They could be produced as consequence of environmental factors, such as chronic smoking, life style, aging, occupation. Genetic factors also contribute to the development of HLD. In Brazil, a very few studies have addressed the genetic influence on HLD occurrence, and no reports of the roll of SNPs in the susceptibility of this disease have been published for a Brazilian population. The current study investigated the potential association between polymorphic variants in rs2294984 and rs61734651 from the COL9A3 gene and HDL. The study included 118 residents from Goiânia-GO (Brazil) divided in two groups. A total of 40 people comprised the group of cases and 78 comprised the control group. From each participant, 4mL of peripheral blood was collected in EDTA. DNA was isolated from biological samples using the commercial kit IlustraBloodGenomicPrepMini Spin® (GE Healthcare, UK), following the manufacturer’s instructions. Isolated DNA was stored at -20oC. The SNPs were genotyped using TaqMan Real Time PCR® (SNP Genotyping kit, da AppliedBiosystems, EUA). Data was annotated in spreadsheets for the statistical analyses. Among cases, there were 17 women and 23 men whose average age was 42.2 years old. For controls, a total of 34 women and 44 men contributed to an average age of 42.6 years old. For SNP s2294984, no statistical defences were observed for either allelic and genotypic frequencies between cases and controls. However, for SNP rs61734651, a significant reduction (about 3x) in the frequency of the C allele was detected among cases. This reduction skewed the distribution of both allelic and genotypic frequencies from CC to CT and TT. The difference between cases and controls was statistically significant (p< 0,05) and the substitution of C for T caused the replacement of the aminoacid arginine by tryptophan in the codon 103 of the α3 chain (Trp3) of collagen IX. The results of the current study indicated the genotype TT was associated with HDL development in adults from central Brazil. The allele Trp3 increased 11% the chance of HDL among cases, when compare to controls. Thus, this study pointed out the need to further investigate the contribution of individual genetic makeup on the development of adult onset HDL.