Identification of a novel DR4 allele, DRB1*0442

A new DRB1 allele encoding DR4, DRB1*0442, was identified in three Caucasia n siblings by reverse in-line hybridization and defined by sequencing based typing. The DRB1*0442 allele differs from DRB1*0404 by a single nucleotide at position 227 (T -->A) of codon 47 in exon 2. At the amino add level, th is substitution results in a change from tyrosine to phenylalanine. Serolog ically, the new allele appears to retain the DR4 antigenicity; however, thi s substitution may affect peptide-binding specificity.