Mutación de novo en el gen BTK en agammaglobulinemia ligada a X. Reporte de un caso del estado Mérida, Venezuela

De novo mutation in BTK gene in X-linked agammaglobulinaemia. A case report in Mérida, Venezuela. The Primary Immunodeficiencies (PIDs) are a group of diseases characterized by defects in the development or function of the immune system due to genetic abnormalities in any of its components. Humoralimmunodeficiencies are the most common PIDs and the congenital agammaglobulinemia represents 10%, and 85% linked to the X chromosome. Also there exist autosomal recessive forms. X-Linked agammaglobulinemia (XLA) is characterized by almost a total absence of B-lymphocytes, causing inability to produce antibodies and a high susceptibility to infection and diminished or absent response to vaccine. We reported an 8 year-old male child who presented repeatedly infection by extracellular encapsulated bacteria since 5 months of life. The laboratory studies revealed persistent hipogammaglobulinemia with diminished B-lymphocytes subpopulation and normal T-lymphocytes cell in peripheral blood. The molecular study showed a mutation R525X in the 16-exon of Bruton´s tyrosine kinase (BTK) gene in both child and mother, but not in grandmother, thus confirming the XLA diagnostic and allowing to conclude that a de novo mutation had occurred in mother. Actually, the patient receives intravenous immunoglobulin treatment and the infections have diminished in both frequency and severity. Early diagnostic through recognition of the warning signs of PIDs next to the appropriate treatment and monitoring is the best tool for the proper management of patients with PIDs, achieving a reduction of that inflammatory process, infections and damage as well as a better quality of life and survival. Las inmunodeficiencias primarias (IDPs) son un conjunto de enfermedades caracterizadas por defectos en el desarrollo y/o función del sistema inmune debido a anomalías genéticas en cualquiera de sus componentes. Las deficiencias de anticuerpos son las IDPs más comunes y dentro de estas la agammaglobulinemia congénita representa el 10%, siendo un 85% ligada al cromosoma X, existiendo también formas autosómicas recesivas. La agammaglobulinemia ligada a X (ALX) consiste en la ausencia casi absoluta de linfocitos B, ocasionando incapacidad de sintetizar anticuerpos y una alta susceptibilidad a la adquisición de infecciones, con respuesta a vacunas disminuida o ausente. Se presenta el caso de un escolar masculino de 8 años de edad quien desde los 5 meses presentó infecciones a repetición principalmente por