HomeIAMURE International Journal of Science and Clinical Laboratoryvol. 5 no. 1 (2014)

Human SNPs Resulting in Novel Mutation of HLA-DRB1 Gene for Salivary sIgA Secretion

Pratiwi Soesilawati | Harianto Notopuro | Istiati Istiati | Afaf Baktir

Discipline: Science



HLA-DRB1 gene is important for controlling antigen peptides presentation to T cell Receptor that encodes salivary sIgA secretion, in turn, preventing Streptococcus mutants’ colonization in dental caries mechanism. The study investigated the Novel Mutation of HLA-DRB1 Gene in Salivary sIgA Secretion. It tested 30 patients high (>300ng/mL) and 30 patients low (<300ng/mL) salivary sIgA level, in high sIgA group: 5 patients match with variant HLA-DRB*1209; 25 with the same SNPs in the Exxon 2 of HLA-DRB1 on nt295 (GC) and nt303(CG) resulting in missense mutation on codon 99 from aspartate to histidine and silent mutation on codon 102. D99H affects protein function. On low salivary sIgA group, 9 patients had two deletions of base 136 and base 153. The frame shift resulted in a premature stop codon 61 amino acids downstream: 10 patients had substitutions of G to T (nucleotide position 313); A to T (nucleotide position 314). This group also had 2 deletions of base 136 and 153, leading to frame shift and premature stop codon; nine patients had substitution of G to T (nucleotide position 312) and A to T (nucleotide 314). The variants produced a truncated protein and the mutations. This confirmed HLA-DRB1 as gene involved in dental caries mechanism and SNPs that may help understand the structure and function of the protein.