Identification and characterization of a novel splice-site mutation in a patient with Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by immunodeficiency, eczema, and thrombocytopenia with small platelets. A wide spectrum of mutations in the Wiskott-Aldrich syndrome protein ( WASP) gene have been identified as causative of the disease. In the present paper, we report on a family with a boy affected by WAS, with a splice-site mutation caused by a T to G substitution in the +2 position of intron 6 (IVS6+2T>G). Expression studies performed in COS-7 and U-937 cells showed that the mutation affected the normal splicing process. As a consequence, an abnormally long transcript of 38 nucleotides is generated. Such missplicing is probably due to the activation of a cryptic splice donor site located 38 nt downstream of exon 6. The translation of such aberrant mRNA will produce a truncated protein with a premature stop at codon 190. Thus, a novel splice-site mutation is reported in a patient with a mild WAS phenotype.