title: Is there heterozygote expression of growth hormone receptor deficiency?
abstract: Expression of heterozygosity for the defect in the growth hormone (GH) receptor has been proposed to be reflected in stature, and in GH binding protein (GHBP) and insulin-like growth factor I (IGF-I) levels in parents and other relatives of patients with GH receptor deficiency (GHRD; Laron syndrome). The Ecuadorean population with GHRD, in which heterozygosity can be accurately determined in clinically unaffected relatives of probands, offers a unique opportunity to consider this issue. It has previously been demonstrated that 17 parents heterozygous for the Ecuadorean mutation of the GH receptor differed little in biochemical measures (GHBP, IGF-I, IGF-II, IGFBP-2 and IGFBP-3) from Ecuadorean controls. Mean height SDS of 24 non-carrier siblings (-1.3 +/- 0.95 SD) and 41 heterozygote siblings or offspring of probands (-1.8 +/- 1.15) did not differ significantly (p = 0.08). Thus, although there may be slight heterozygote expression of the defective gene for the GH receptor, there is no rationale for counselling based on such minimal variation.
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville.
authors.forename: A L
authors.initials: AL
authors.lastname: Rosenbloom
authors.forename: J
authors.initials: J
authors.lastname: Guevara-Aguirre
authors.forename: R G
authors.initials: RG
authors.lastname: Rosenfeld
authors.forename: P J
authors.initials: PJ
authors.lastname: Fielder
mesh_terms: D002352:Carrier Proteins / Q000032:analysis; D004484:Ecuador; D005260:Female; D006580:Genetic Carrier Screening; D006130:Growth Disorders / Q000235:genetics; D013006:Growth Hormone / Q000378:metabolism; D006579:Heterozygote; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D011986:Receptors, Somatotropin / Q000172:deficiency* / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D011986:Receptors, Somatotropin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; C051815:somatotropin-binding protein