Novel BTK mutation in X-linked agammaglobulinemia: Report of a 17-year-old male.

INTRODUCTION AND OBJECTIVES: X-linked agammaglobulinemia (XLA), the first known primary immunodeficiency, is caused by rare mutations in Bruton's tyrosine kinase (BTK) gene. Mutations in the BTK gene lead to a failure in the development and maturation of B-cell linage. A decreased number of B-cells results in agammaglobulinemia and increased susceptibility to a variety of infections. Therefore, patients with XLA usually manifest with repetitive bacterial infections, such as upper respiratory tract infections, septic arthritis, osteomyelitis, and urinary tract infections, since their infancy. PATIENTS: We report a 17-year-old Iranian boy with XLA, referred to us with a history of severe and recurrent episodes of bacterial infections for a period of six years. RESULTS: Genetic analysis using the whole Exome sequencing revealed a hemizygous missense mutation in the BTK gene (c.428 A > T, p.His143Leu). CONCLUSION: To our knowledge, c.428 A > T has not been reported in the BTK gene.

A novel homozygous RAG1 mutation is associated with severe combined immunodeficiency and neurological presentations.

INTRODUCTION AND OBJECTIVES: Severe combined immunodeficiency (SCID) is a subset of primary immunodeficiency diseases caused by a hereditary deficiency of the adaptive immune system. Mutation in recombination activating gene (RAG) is known as the underlying genetic cause of SCID. RAG protein plays a pivotal role in V(D)J recombination which is the main process to assemble lymphocyte antigen receptors during T- and B-cell development. The patients are characterized by recurrent infections, failure to thrive, chronic diarrhea, and fever, in early infancy. Herein, we present a case of SCID with rare neurological manifestations affected by a mutation in RAG1. PATIENTS AND METHODS: The patient was a 15-month-old infant born to a consanguineous family. She was presented with neurological abnormalities including facial nerve palsy, seizure, and decreased consciousness. Next-generation sequencing (NGS)-based primary immunodeficiency disease (PID)-gene panel screen and Sanger sequencing were performed to identify the genetic mutation. RESULTS: We found a novel homozygous missense mutation in RAG1, c.1210C>T,p.Arg404Trp, which was predicted to be deleterious (combined annotation dependent depletion, CADD score of 27.4). Both parents were heterozygous carriers for this mutation. According to her laboratory data, both T cell and B cell numbers were decreased and the patient was diagnosed as RAG1- SCID. CONCLUSIONS: SCID is a pediatric emergency with a variety of manifestations in infants. Therefore, accurate diagnosis importantly in the case of rare manifestations must be considered in these patients. Our findings point toward the importance of genetic assessment for early diagnosis and timely treatment of this disorder.