A rare autosomal recessive primary immunodeficiency characterised by absence of HLA class II molecules on the surface of immune cells, leading to severely impaired cellular and humoral immune response to foreign antigens, severe CD4+ T-cell lymphopenia, and hypogammaglobulinaemia. The disease clinically manifests with early onset of severe and recurrent infections mainly of the respiratory and gastrointestinal tract, protracted diarrhoea with failure to thrive, and autoimmune disease, and is frequently fatal in childhood. [from
SNOMEDCT_US]