Definition: "DSACS5" refers to a rare genetic disorder characterized by severe hypothyroidism, associated with an underlying immune deficiency or inflammation. The term "DSACS5" encompasses three distinct disorders: Dysfunctional Somatic Cell Transplantation Syndrome 5 (DCS-5), which causes congenital thyroid hormone deficiency due to abnormal somatic cell transplants, and the specific disorder called DCS-5 Type IV (Type IV DCs) that affects the immune system. These conditions are often caused by genetic abnormalities or autoimmune diseases.