PCR BASED G3M(11) AND G3M(21) ALLOTYPING AMONGST RHEUMATOID ARTHRITIS PATIENTS

G3m(11) and G3m(21) allotypes have been analyzed in a group of Rheumatoid Arthritis patients and Normal Controls belonging to Punjabi population of North Western India. The PCR amplified DNA fragment, comprising a major portion of the second and third constant region domains CH2 and CH3 of the human IgG3 heavy chain gene, with the help of a pair of primers, was digested with restriction endonuclease Rsa1, and the pattern so generated was analyzed on PAGE (12%) and visualized with silver staining. Individuals homozygous for G3m(11) and G3m(21) and those heterozygous for G3m(11, 21) revealed differences in three codons for the amino acid residues. Individuals homozygous for G3m(11) have Proline, Phenylalanine and Serine at these positions, while those homozygous for G3m(21) showed Leucine, Tyrosine and Asparagine at the corresponding positions. However, the heterozygous G3m(11, 21) individuals displayed the mixed pattern for, both G3m(11) and G3m(21) codons. In the present study, G3m(11) and G3m(21) allotypic analysis revealed frequencies of Gm11 & Gm21alleles to be 0.483 & 0.516 amongst the patients and 0.446 & 0.554 amongst the controls. Chi-square analysis, however, revealed statistically nonsignificant differences between the two series.