title: The respiratory presentation of severe combined immunodeficiency in two Mennonite children at a tertiary centre highlighting the importance of recognizing this pediatric emergency.
abstract: Severe combined immunodeficiency (SCID) is considered to be a pediatric emergency, with respiratory distress being the most common presenting symptom. The authors present two cases of SCID in children <4 months of age with respiratory distress at a tertiary care centre due to a recently described homozygous CD3 delta mutation found only in the Mexican Mennonite population. Failure to respond to broad-spectrum antibiotics prompted investigation for possible SCID. Bronchial alveolar lavage fluid from both patients grew Pneumocystis jiroveci, and flow cytometry revealed absent T cells. The CD3 delta gene is believed to be important in T cell differentiation and maturation. The present article reminds pediatricians and pediatric respirologists that the key to diagnosing SCID is to have a high index of suspicion if there is poor response to conventional therapies.
authors.forename: Simon
authors.initials: S
authors.lastname: Lam
authors.forename: Fotini Dimitriou
authors.initials: FD
authors.lastname: Kavadas
authors.forename: Seemab
authors.initials: S
authors.lastname: Haider
authors.forename: Mary Elizabeth
authors.initials: ME
authors.lastname: Noseworthy
mesh_terms: D017252:CD3 Complex / Q000235:genetics*; D002170:Canada; D006801:Humans; D007223:Infant; D008297:Male; D008800:Mexico / Q000208:ethnology; D011859:Radiography; D012141:Respiratory Tract Infections / Q000000981:diagnostic imaging* / Q000276:immunology; D016511:Severe Combined Immunodeficiency / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology; D062606:Tertiary Care Centers
chemical_list: D017252:CD3 Complex; C472562:CD3delta antigen