Association of transcobalamine II gene polymorphisms and serum homocysteine, vitamin B12 and folate levels with ulcerative colitis among Chinese patients

Abstract

To assess the association of transcobalamine II (TCN2) gene polymorphisms and serum levels of homocysteine (Hcy), vitamin B12 and folate with ulcerative colitis (UC) among Chinese patients. For 397 UC patients and 574 controls, two single nucleotide polymorphisms of the TCN2 gene (rs1801198, rs9606756) were tested with an improved multiple ligase detection reaction method. Serum Hcy, vitamin B12 and folate were measured with an enzymatic cycling assay and an chemiluminescence immunoassay, respectively. The allelic and genotypic frequencies of rs1801198 and rs9606756 did not differ significantly between the two groups (all P> 0.05). Compared with those of the control group, the frequencies of G allele and CG+GG genotype of rs1801198 were greater in patients with moderate and severe UC (both P< 0.05). The same conclusion may also be drawn for the G allele and AG genotype of rs9606756 (both P< 0.05). Compared with the controls, average Hcy level was enhanced in UC patients (P< 0.01), whereas average vitamin B12 and folate levels were decreased in UC patients (both P< 0.01). In both groups, the average level of Hcy was lower in individuals carrying CC of (rs1801198) than in those with CG+GG (both P< 0.05). A similar conclusion was also drawn for individuals with AA of rs9606756 when compared with those carrying AG(both P< 0.05). Compared with patients with mild UC, average Hcy level was increased in those with moderate and severe UC (P< 0.01), while average vitamin B12 and folate levels were decreased in those with moderate and severe UC (both P< 0.01). The prevalence of hyperhomocysteinemia(HHcy), vitamin B12 deficiency and folate deficiency was greater in UC patients than in controls (all P< 0.01). In UC patients, the level of Hcy was negatively correlated with those of vitamin B12 (P< 0.01), albumin(P< 0.01), red blood cells(P< 0.01) and platelet (P< 0.05), but positively correlated with white blood cells(P< 0.01) and Mayo score (P< 0.01). Both HHcy and folate deficiency were independent risk factors for UC (OR=4.173, OR=5.206, both P< 0.01). TCN2 (rs1801198, rs9606756) variations, as well as serum levels of Hcy, vitamin B12 and folate, are correlated with UC. Both HHcy and folate deficiency are independent risk factors for UC.