(a) Sequences of the TAP1 gene of KMW, the mother (UTT), and a healthy control. cDNA sequences of the TAP1 gene revealed KMW to be homozygous for TAP1*0102N, an allele with a G deletion in codon 200. Genomic DNA sequencing of the TAP1 gene also revealed a point mutation of G→A on 536 bp in intron 1 of the TAP1*0102N of KMW and the family members (partially filled symbols in Fig. 1b are heterozygous for TAP1*0102N, and only the sequence of the mother is shown). PCR products of the TAP1 gene were sequenced by automated sequencing as described in Methods. (b) Sequences of the TAP1*0101 and TAP1*0102N. G was substituted to A on 536 bp in intron 1 of the TAP1*0102N, which resulted in an altered splice acceptor site and deletion of G in codon 200 of mRNA. This deletion caused a frameshift and resulted in the premature appearance of a stop codon at 228 and the synthesis of a truncated TAP1 protein. (GenBank accession numbers: TAP1*0102N cDNA sequence, AB012644; TAP1*0102N genomic sequence, AB012645.) TAP, transporter associated with antigen processing.