Absence of human chorionic somatomammotropin during pregnancy associated with two types of gene deletion

Abstract

Complete absence of human somatomammotropin (hCS) was demonstrated in two patients experiencing an otherwise uneventful pregnancy. After delivery, DNA was prepared from the neonate blood or from the placenta and the integrity of the hCS-hGH gene cluster was investigated by Southern blotting and hybridization with an hCS cDNA probe. Patient 1 was found to be homozygous for a deletion involving hCS-A, hGH-V, and hCS-B. Patient 2 was a double heterozygote, with one chromosome bearing the same deletion as that of patient 1, while in the other, only the hCS-A gene was missing. Considerations relative to the frequency of the defect are derived from the present results.

Regulation of Maternal Metabolism by Pituitary and Placental Hormones: Roles in Fetal Development and Metabolic Programming

“…These findings suggest that hPL and placental GH may act in concert to regulate maternal metabolism and fetal development. However, fetal growth was normal in two other cases of combined hPL and GH-V gene deletions [32, 33, 39]. …”

Aspects of placental growth hormone physiology

“…Conversely, neither hPL [85][86][87][88], Prl [89] nor GH [90] seem essential for pregnancy. Only a few cases of deletion of the GH-V gene have been reported [88,[91][92][93][94][95]. In these reports, one or both genes encoding hPL (hCS-A and hCS-B) were deleted as well, thus the pregnancies were, when assayed, characterised by unmeasurable levels of hPL and low levels of (pituitary) growth hormone in maternal blood; nevertheless, healthy, normal weight babies were delivered in these reports, apart from the latter two reports in which birth weights were below normal.…”

Ontogeny of Growth Hormone Releasing Hormone and Insulin-Like Growth Factors-I and-II Messenger RNA in Rat Placenta

“…Although production of PL is massive, appears early in human pregnan cy, and increases in parallel with placental weight, its absence in humans does not seem to be detrimental to growth. Infants with complete deletions of the PL genes have normal prenatal growth, despite extremely low levels of this hormone in the maternal circulation (31,32). Although it has both lactogen ic and somatogenic properties (33), it is not potent as a postnatal GH (34).…”