BACKGROUND: The diagnosis of X-linked agammaglobulinemia (XLA) is not always clearcut. Not all XLA conform to the classic phenotype and less than 50% of affected boys have a family history of immunodeficiency. Mutations in the gene for Bruton's tyrosine kinase (BTK) are responsible for the majority of agammaglobulinemia cases. However, a certain proportion of patients may have mutations involving other genes, although they show with an XLA phenotype. We performed BTK gene mutation analysis in 37 males with presumed XLA and analyzed the pattern of X-chromosome inactivation (XCI) in 31 mothers to evaluate the relevance of these approaches to diagnosis and genetic counseling. MATERIALS AND METHODS: Twenty affected males with a sporadic occurrence and 17 familial cases belonging to nine families were enrolled within the framework of the Italian Multicenter Clinical Study on XLA. We used non-isotopic RNase cleavage assay (NIRCA), followed by cDNA sequence determination to screen for BTK mutations and X-chromosome inactivation analysis for carrier detection. RESULTS: Using the cDNA-based approach, the identification of BTK gene abnormalities confirmed the clinical diagnosis of XLA in 31 of 37 affected infants. Missense was the most frequent mutational event and the kinase domain was mostly involved. In addition, nine novel mutations were identified. In sporadic cases, BTK gene abnormalities were identified in 9 out of 10 patients whose mothers had a nonrandom pattern of XCI and in 5 out of 6 patients whose mother had a random pattern of XCI. With the exception of one family, all patients with a familial occurrence and born to mothers with a nonrandom pattern of XCI had mutations of the BTK gene. CONCLUSIONS: Our findings indicate that in sporadic cases BTK gene sequencing is the only reliable tool for a definitive diagnosis of XLA and support XCI as the first diagnostic tool in the mothers of affected males in multiple generations. Furthermore, our molecular analysis confirms that 10-20% of BTK-unaltered patients have disorders caused by defects in other genes.
BACKGROUND: The diagnosis of X-linked agammaglobulinemia (XLA) is not always clearcut. Not all XLA conform to the classic phenotype and less than 50% of affected boys have a family history of immunodeficiency. Mutations in the gene for Bruton's tyrosine kinase (BTK) are responsible for the majority of agammaglobulinemia cases. However, a certain proportion of patients may have mutations involving other genes, although they show with an XLA phenotype. We performed BTK gene mutation analysis in 37 males with presumed XLA and analyzed the pattern of X-chromosome inactivation (XCI) in 31 mothers to evaluate the relevance of these approaches to diagnosis and genetic counseling. MATERIALS AND METHODS: Twenty affected males with a sporadic occurrence and 17 familial cases belonging to nine families were enrolled within the framework of the Italian Multicenter Clinical Study on XLA. We used non-isotopic RNase cleavage assay (NIRCA), followed by cDNA sequence determination to screen for BTK mutations and X-chromosome inactivation analysis for carrier detection. RESULTS: Using the cDNA-based approach, the identification of BTK gene abnormalities confirmed the clinical diagnosis of XLA in 31 of 37 affected infants. Missense was the most frequent mutational event and the kinase domain was mostly involved. In addition, nine novel mutations were identified. In sporadic cases, BTK gene abnormalities were identified in 9 out of 10 patients whose mothers had a nonrandom pattern of XCI and in 5 out of 6 patients whose mother had a random pattern of XCI. With the exception of one family, all patients with a familial occurrence and born to mothers with a nonrandom pattern of XCI had mutations of the BTK gene. CONCLUSIONS: Our findings indicate that in sporadic cases BTK gene sequencing is the only reliable tool for a definitive diagnosis of XLA and support XCI as the first diagnostic tool in the mothers of affected males in multiple generations. Furthermore, our molecular analysis confirms that 10-20% of BTK-unaltered patients have disorders caused by defects in other genes.
Authors: Jeroen G Noordzij; Sandra de Bruin-Versteeg; Nico G Hartwig; Corry M R Weemaes; Egbert J A Gerritsen; Eva Bernatowska; Stefaan van Lierde; Ronald de Groot; Jacques J M van Dongen Journal: J Clin Immunol Date: 2002-09 Impact factor: 8.317
Authors: M C Gagliardi; A Finocchi; P Orlandi; L Cursi; C Cancrini; V Moschese; T Miyawaki; P Rossi Journal: Clin Exp Immunol Date: 2003-07 Impact factor: 4.330
Authors: Zeinab A El-Sayed; Irina Abramova; Juan Carlos Aldave; Waleed Al-Herz; Liliana Bezrodnik; Rachida Boukari; Ahmed Aziz Bousfiha; Caterina Cancrini; Antonio Condino-Neto; Ghassan Dbaibo; Beata Derfalvi; Figen Dogu; J David M Edgar; Brian Eley; Rasha Hasan El-Owaidy; Sara Elva Espinosa-Padilla; Nermeen Galal; Filomeen Haerynck; Rima Hanna-Wakim; Elham Hossny; Aydan Ikinciogullari; Ebtihal Kamal; Hirokazu Kanegane; Nadia Kechout; Yu Lung Lau; Tomohiro Morio; Viviana Moschese; Joao Farela Neves; Monia Ouederni; Roberto Paganelli; Kenneth Paris; Claudio Pignata; Alessandro Plebani; Farah Naz Qamar; Sonia Qureshi; Nita Radhakrishnan; Nima Rezaei; Nelson Rosario; John Routes; Berta Sanchez; Anna Sediva; Mikko Rj Seppanen; Edith Gonzalez Serrano; Anna Shcherbina; Surjit Singh; Sangeetha Siniah; Guiseppe Spadaro; Mimi Tang; Ana Maria Vinet; Alla Volokha; Kathleen E Sullivan Journal: World Allergy Organ J Date: 2019-03-22 Impact factor: 4.084