Severe combined immunodeficiency: A tale of two brothers.

Correspondence: Canadian Paediatric Surveillance Program, 2305 St Laurent Boulevard, Ottawa, Ontario K1G 4J8. Telephone 613-526-9397 ext 239, fax 613-526-3332, e-mail [email protected] Accepted for publication April 16, 2008 Amale infant presented at five months of age with eventually fatal respiratory syncytial virus infection, and a history of chronic oral candidiasis and failure to thrive. A blood count to investigate neonatal jaundice had demonstrated lymphopenia (0.9×109/L), but this was not followed up in the newborn period. The clinical diagnosis of severe combined immunodeficiency (SCID) was confirmed by hypogammaglobulinemia and a deficiency of T cell numbers and function. X-linked SCID was suspected from the infant’s family history, which showed that three maternal uncles died in infancy, and it was confirmed by mutation analysis (1). The mother became pregnant again. Genetic testing on a chorionic villous sample showed an affected fetus. Chorionic villous sample human leukocyte antigen tissue typing results submitted to the bone marrow registry found a stem cell donor. The baby was delivered expectantly into conditions that were kept as sterile as possible, was treated with prophylactic antibiotics against Pneumocystis jiroveci, previously known as Pneumocystis carinii (a common pathogen in severe immunodeficiency), and was kept in protective isolation until he underwent a transplant two weeks after delivery. He was discharged home after three weeks, with early signs of bone marrow engraftment. He has had a full recovery, with a normally functioning immune system. He requires no ongoing therapy and should enjoy a normal life.