MHC class II deficiency
Immunodeficiency by defective expression of HLA class 2 is a rare primary genetic immunodeficiency disorder characterized by partial or complete absence of human leukocyte antigen class 2 expression resulting in severe defect in both cellular and humoral immune response to antigens. The disorder presents clinically as marked susceptibility to infections, severe malabsorption and failure to thrive and is often fatal in early childhood.