Nucleotide sequence analysis of amplified cDNA from an SH(+) individual. The region of the autoradiograph shown here includes the sequence from base 257 to 275. The nucleotide change from a C to an A (arrow) at position 266 in the SH(+) individual results in an alanine (GCT) to an aspartic acid (GAT) amino acid substitution at residue 78 of the FcγRIIIb polypeptide.