Combined immunodeficiency due to T-cell immunodeficiency, with genital alopecia and absent thymus, lymphopenia, and normal or increased immunoglobulin levels. Multiple recurrent infections and failure to thrive are common clinical features. Other features include reduced lymphoid tissue, thymus abnormalities, and antibody synthesis irregularities. Also called thymic aplasia with normal immunoglobulins. Autosomal recessive or X-linked recessive inheritance. Immune defect due to absence of thymus. Recurrent infections may present as life-threatening events, particularly in infants, and include bronchiectasis, chronic bronchitis, candidiasis, diarrhea, urinary tract infection, varicella, skin and pulmonary infections, and gram-negative sepsis. Onset is at birth or in infancy.