Severe Combined Immunodeficiency (SCID) is a rare genetic disorder that affects the immune system, making it extremely difficult for the body to fight off infections. Individuals with SCID have a deficiency in both T cells and B cells, which are crucial for a healthy immune response. This condition is often diagnosed in infancy, as affected children may experience frequent and severe infections. SCID can be caused by various genetic mutations, and it is typically inherited in an X-linked or autosomal recessive manner. Treatment options include bone marrow transplantation, which can restore immune function, and gene therapy, which aims to correct the underlying genetic defect. Early diagnosis and intervention are critical for improving outcomes in affected individuals.