Influence of Transcobalamin II (TCN2) and its receptor (CD320) gene polymorphisms on circulating TCN2 and CD320...

Vitamin B12 deficiency is a health concern leading to neurological and hematological disorders with genetic factors. This study investigated the effects of polymorphisms in the Transcobalamin II (TCN2, rs1801198) gene and its receptor CD320 (rs2336573) on serum vitamin B12 levels, circulating TCN2 and CD320 levels, and basic hematological parameters.

Patients with vitamin B12 deficiency and healthy controls were included in the study. Genotyping was performed using the TaqMan SNP method, and serum TCN2 and CD320 concentrations were measured by ELISA. Vitamin B12 and hematological parameters were measured via autoanalyzer.

Genotype and allele frequencies of TCN2 and CD320 polymorphisms did not differ significantly between patients and controls. Among individuals with vitamin B12 deficiency, carriers of the TCN2 CG genotype showed higher mean corpuscular volume (MCV) and lower total iron-binding capacity (TIBC), whereas those with the CC genotype had reduced CD320 levels. Carriers of the CD320 CC genotype showed lower CD320 and TIBC levels compared with controls. In individuals with B12 deficiency and the TCN2 CC genotype, B12 levels were inversely related to MCV and positively correlated with TCN2 and CD320 levels. Likewise, in CD320 CC carriers, CD320 levels showed a positive correlation with both vitamin B12 and TCN2.

Although no direct genetic association with B12 deficiency was identified, observed reductions in TCN2 and CD320 levels, along with alterations in related biochemical parameters, suggest a potential role of these genes in B12 metabolism. More extensive studies are needed to confirm these findings.