Around the world, the most common cause of<unk>  is iodine deficiency, but in most of the developed world and areas of adequate environmental iodine, cases are due to a combination of known and unknown causes. Most commonly there is a defect of development of the thyroid gland itself, resulting in an absent (athyreosis) or underdeveloped (hypoplastic) gland. However, recent studies have shown an increase in the number of cases caused by gland in situ (termed dyshormonogenesis when there is a defect in hormone production). A hypoplastic gland may develop higher in the neck or even in the back of the tongue. A gland in the wrong place is referred to as ectopic, and an ectopic gland at the base or back of the tongue is a lingual thyroid. Some of these cases of developmentally abnormal glands result from genetic defects, and some are "sporadic," with no identifiable cause. One Japanese study found a statistical correlation between certain organochlorine insecticides and dioxin-like<unk> emicals in the milk of mothers who had given birth to infants with<unk> . Neonatal<unk>  has been reported in cases of infants exposed to lithium, a mood stabilizer used to treat bipolar disorder, in utero. In some instances,<unk>  detected by screening may be transient. One common cause of this is the presence of maternal antibodies that temporarily impair thyroid function for several weeks. The word "cretinism" is an old term for the state of mental and physical retardation resulting from untreated<unk> , usually due to iodine deficiency from birth because of low iodine levels in the soil and local food sources. The term, like so many other 19th century medical terms, acquired pejorative connotations as it became used in lay speech. It is now deprecated; ICD-10 uses "congenital iodine deficiency syndrome" with additional specifiers for the various types. Genetics<unk>  can also occur due to genetic defects of thyroxine or triiodothyronine synthesis within a structurally normal gland. Among specific defects are thyrotropin (TSH) resistance, iodine trapping defect, organification defect, thyroglobulin, and iodotyrosine deiodinase deficiency. In a small proportion of cases of<unk> , the defect is due to a deficiency of thyroid-stimulating hormone, either isolated or as part of congenital hypopituitarism. Genetic types of nongoitrous<unk>  include: OMIM Name Gene<unk> , nongoitrous 1<unk> NG1 TSHR<unk> NG2 PAX8<unk> NG3 ? at 15q25.3-q26.1<unk> NG4 TSHB<unk> NG5 NKX2-5 Nongoitrous<unk>  has been described as the "most prevalent inborn endocrine disorder".
Congenital hypothyroidism
Congenital iodine deficiency syndrome
Congenital adrenal hyperplasia
Thyroid dysgenesis
Late onset congenital adrenal hyperplasia
Lipoid congenital adrenal hyperplasia
Congenital hyperinsulinism
Isolated growth hormone deficiency