Clinical and mutational features of Vietnamese children with X-linked agammaglobulinemia.

Background: X-linked agammaglobulinemia (XLA) is a primary immune deficiency characterized by recurrent bacterial infections and profoundly depressed serum immunoglobulin levels and circulating mature B cells. It is caused by mutations of the Bruton tyrosine kinase (BTK) gene and is the most common form of inherited antibody deficiency. To our knowledge, this is the first report of XLA from Vietnam.
Methods: We investigated the BTK gene mutations and clinical features of four unrelated Vietnamese children.
Results: The mean ages at onset and at diagnosis were 2.5 and 8 years, respectively. All patients had a medical history of otitis media, pneumonia, and septicemia at the time of diagnosis. Other infections reported included sinusitis, bronchiectasis, arthritis, skin infections, meningitis, and recurrent diarrhea. We identified one previously reported mutation (c.441G >A) and three novel mutations: two frameshifts (c.1770delG and c.1742 delG), and one nonsense (c.1249A >T).
Conclusions: The delayed diagnosis may be attributable to insufficient awareness of this rare disease on the background of frequent infections even in the immunocompetent pediatric population in Vietnam. Our results further support the importance of molecular genetic testing in diagnosis of XLA.