Diagnostic criteria were based on recommendations by the Pan-American Group for Immunodeficiency and the European Society for Immunodeficiencies, which included failure to thrive, persistent diarrhea, respiratory symptoms, and oral candidiasis, or Pneumocystis pneumonia, severe bacterial infections, and disseminated Bacillus Calmette-Guérin (BCG) infection during the first 2 to 7 months of life.