Immunoglobulin superfamily, member 1 (IGSF1) deficiency syndrome is a rare disorder (1 in 100,000) of central hypothyroidism, testicular enlargement, hypoprolactinemia, and growth hormone dysregulation caused by loss of function mutations in the X-linked IGSF1 gene [1–4]. This evidence concerns the gene IGSF1 and Central hypothyroidism.