The group of hereditary immune disorders predominantly involving T-lymphocytes (their number or function) or both T- and B-lymphocytes is so-called T-cell and B-cell combined deficiencies. In general, these immunodeficiencies are more serious than isolated antibody deficiencies and compose 20% of all severe hereditary immune disorders.
The majority of these diseases are autosomal recessive. The disease manifestation occurs early after the birth, mostly during the first six months of age.
The recurrent and severe infections caused by intracellular bacteria, viruses, fungi, mycobacteria and opportune pathogens dominate in the clinical picture of severe cellular deficiencies.