Final answer:
Severe combined immunodeficiency (SCID) is an inherited condition caused by various genetic defects that impair B-cells and T-cells, preventing the development of an effective adaptive immune response.
Step-by-step explanation:
An inborn disease called severe combined immunodeficiency disease (SCID) is caused by various genetic defects that result in the impairment of both B-cell and T-cell functions. This condition prevents the development of an effective adaptive immune response, as patients with SCID have defects in T-cell dependent antibody responses and cell-mediated immune responses.
They are also unable to develop immunological memory, rendering vaccines ineffective for them. A notable form of SCID is X-linked SCID, accounting for about 50% of cases and primarily affecting males. Without adequate treatment, which may include bone marrow transplants, individuals with SCID are at risk of developing severe, often fatal, opportunistic infections.