Final answer:
The genetic defect in either RAG-1 or RAG-2 genes leads to SCID, which causes impaired T and B cell development, leading to severely compromised immune function.
Step-by-step explanation:
The immunological consequence of severe combined immunodeficiency disease (SCID) caused by a genetic defect in either RAG-1 or RAG-2 genes is impaired T and B cell development
SCID is a condition in which both the B cell and T cell arms of the adaptive immune response are affected. The disease is caused by various genetic defects that result in the failure to produce functional B cells and T cells, making patients highly susceptible to infections. Without functional B and T cells, individuals cannot mount effective immune responses, and as such, they cannot develop immunological memory, rendering vaccines ineffective. This condition can be life-threatening, typically resulting in severe, opportunistic infections shortly after birth.