RESUMEN
Wiskott-Aldrich syndrome (WAS), is an X-linked immunodeficiency disease caused by mutations of the WAS protein (WASP) gene, characterized by thrombocytopenia, eczema and recurrent infections. X-linked thrombocytopenia (XLT) is a milder form with only platelet abnormalities. Cumulative mutation data have revealed that WASP genotypes are highly variable among WAS patients. By SSCP analysis, we determined the location of the mutation in 23 WAS patients from 17 unrelated families with variable clinical phenotypes. Direct sequence analysis of genomic DNA showed 9 novel mutations (Q52H, G70W, 393del7, Ex 7 Ex11del, IVS 8+1G-->C, 925delG, 959ins38, 1380del8, and IVS 2+2T-->C) and 8 known mutations distributed throughout the WAS gene. This is the first report of WAS gene mutations from a Latin American country.
Asunto(s)
Mutación/genética , Proteínas/genética , Síndrome de Wiskott-Aldrich/genética , Argentina/epidemiología , Análisis Mutacional de ADN , Exones/genética , Pruebas Genéticas , Genotipo , Humanos , Intrones/genética , Masculino , Fenotipo , Polimorfismo Conformacional Retorcido-Simple , Síndrome de Wiskott-Aldrich/epidemiología , Síndrome de Wiskott-Aldrich/fisiopatología , Proteína del Síndrome de Wiskott-AldrichRESUMEN
The block in differentiation from pro-B to pre-B cells results in a selective defect in the humoral immune response characteristic of human X-linked agammaglobulinemia (XLA). Mutations of Bruton tyrosine kinase (BTK) gene have been identified as the cause of XLA. Mutation detection is the most reliable method for making a definitive diagnosis, except when clinical and laboratory findings are distinctive and coupled with history of X-linked inheritance. To provide a definitive diagnosis to 40 families incorporated in the Argentinian Primary Immunodeficiencies Registry we analysed the BTK gene by SSCP analysis as screening method for XLA, followed by direct sequencing. The molecular defect was localized in 45 patients from 34 unrelated families. From the 34 independent mutations identified, 16 were previously undescribed, 31 were unique mutations, 22 were exonic single nucleotide changes (16 missense and 6 nonsense) and four intronic mutations. Because five families had clinical, immunological and inheritance data sufficient for a definitive diagnosis, our study allowed 37 patients from 29 families previously categorized probable/ possible XLA, have now definitive diagnosis leading to appropriate genetic counseling.