Isolated growth hormone deficiency (IGHD) is conditions associated with childhood growth failure due to lack of growth hormone (GH) action, and not necessarily associated with other pituitary hormone deficiencies or with an organic lesion. About 5-30% of patients are found to have affected first-degree relatives, suggesting genetic causes. IGHD has been classified into three types. IGHD type 1, characterized by autosomal recessive transmission, is further separated into subtypes 1A and 1B. The phenotype of IGHD type 1B is milder than that of IGHD type 1A. IGHD type 2 is inherited in an autosomal dominant pattern. IGHD type 3 is an X-linked recessive disorder with a highly variable phenotype. Some individuals have an associated agammaglobulinemia.
