A new HLA-A1 mutation: a novel, null variant allele.

From an unusually informative family of 8 with near identical parental haplotypes (a and c), which differed by a single nucleotide substitution, we identified a new HLA-A1 null variant. While serologic antigen typing initially showed a "blank" allele in maternal haplotype "c" and 2 male offspring, more sophisticated DNA molecular HLA typing subsequently revealed the presence of a novel HLA-A0101 allele. Sequence-based typing showed a point mutation consisting of a nucleotide substitution of a cytosine for a guanine at nucleotide 215 yielding an amino acid change of arginine to proline at codon 48 in exon 2 (R48P).