A NEW B18 SEQUENCE (B-ASTERISK-1802) FROM ASIAN INDIVIDUALS

A new HLA-B18 allele (B(*)1802) derived from a Thai individual was sequenced. Comparison of this B18 nucleotide sequence with the published B(*)1801 sequence indicated that this Asian B18 allele has a nucleotide sequence different from that of B(*)1801. Three nucleotide changes were observed in exon 3, in which two substitutions at codon 97, AGG in B(*)1801 to AAT in the B(*)1802, result in an amino acid change from arginine to asparagine. The residue (97)Asn has also been described in some B27 subtypes. A silent mutation was also observed at codon 99, TAC in B(*)1801 to TAT in the B(*)1802. This sequence has been reported in many class I alleles published so far. Moreover, 18 HLA-B18-positive samples were examined by the PCR-SSO method using specific probes for B(*)1801 and B(*)1802. The results demonstrated that three Asian samples possess B(*)1802 and share HLA-Cw7, DR12, and DQ7.