Mutations of Bruton's tyrosine kinase gene in Brazilian patients with X-linked agammaglobulinemia.
Mutations in Bruton's tyrosine kinase (BTK) gene are responsible for X-linked agammaglobulinemia (XLA), which is characterized by recurrent bacterial infections, profound hypogammaglobulinemia, and decreased numbers of mature B cells in peripheral blood. We evaluated 5 male Brazilian patients, ranging from 3 to 10 years of age, from unrelated families, whose diagnosis was based on recurrent infections, markedly reduced levels of IgM, IgG and IgA, and circulating B cell numbers <2%. BTK gene analysis was carried out using PCR-SSCP followed by sequencing. We detected three novel (Ala347fsX55, I355T, and Thr324fsX24) and two previously reported mutations (Q196X and E441X). Flow cytometry revealed a reduced expression of BTK protein in patients and a mosaic pattern of BTK expression was obtained from mothers, indicating that they were XLA carriers.
Ramalho
V D
VD
Centro de Investigação em Pediatria, Departamento de Pediatria, Universidade Estadual de Campinas, SP, Brasil.
Oliveira Júnior
E B
EB
Tani
S M
SM
Roxo Júnior
P
P
Vilela
M M S
MM
D000077329:Agammaglobulinaemia Tyrosine Kinase; D000361:Agammaglobulinemia / Q000201:enzymology / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry; D040181:Genetic Diseases, X-Linked / Q000201:enzymology / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011505:Protein-Tyrosine Kinases / Q000235:genetics*
D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human