POU1F1 (Pit-1; Gene ID 5449) is an anterior pituitary transcriptional factor, and POU1F1 mutation is known to cause anterior pituitary hypoplasia, growth hormone and prolactin deficiency and various degree of hypothyroidism.
The genetic abnormalities include mutations within: (1) Hesx1 (IGHD, SOD or CPHD); (2) Lhx3 (CPHD with preservation of cortisol secretion and a short stiff neck); (3) Lhx4 (GH, TSH and ACTH deficiency with cerebellar hypoplasia); (4) Prop1 (variable CPHD often associated with pituitary masses); (5) POU1F1 (GH, prolactin and TSH deficiency); (6) GHRHR (IGHD) and (7) GH1 (IGHD).
However, as the involvement of PIT1 mutation is rare in Russia, the other negative cases need to be analyzed for another candidate gene responsible for combined GH/Pr/TSH deficiency.
Fetomaternal Pit-1 deficiency resulted in unmitigated fetal hypothyroidism that unmasked thyroid hormone as a potent endogenous drive of fetal maturation and revealed placental transfer of maternal T4 as a rescue mechanism for infants with congenital hypothyroidism, preventing fetal and neonatal symptoms of thyroid deficiency and safeguarding developmental potential.