Unique nonsense mutations are identified in patients HLH-SM and HLH-MP.

(A) Automated sequence analysis of exon 2 reveals a C462T nucleotide substitution (shown with an arrow) in patient HLH-SM (lower left-hand panel), that is predicted to substitute a stop codon for Arg55. Similarly, sequence analysis of exon 3 reveals a T527A nucleotide change in patient HLH-MP (lower right-hand panel), changing Tyr76 to a stop codon. (B) Schematic representation of the full-length SH2D1A complementary DNA and protein, and the location of both point mutations that are predicted to result in premature truncation within the SH2D1A SH2 domain.