Novel compound heterozygous mutations of the growth hormone-releasing hormone receptor gene in a case of isolated growth hormone deficiency

• Published in: Growth hormone & IGF research 2013-08, Vol.23 (4), p.89-97
• Main Authors: Soneda, Akiko, Adachi, Masanori, Muroya, Koji, Asakura, Yumi, Takagi, Masaki, Hasegawa, Tomonobu, Inoue, Hiroshi, Itakura, Mitsuo
• Format: Article
• Language: English
• Subjects: Advanced Basic Science; Amino Acid Sequence; Blotting, Western; Cell Proliferation; Child, Preschool; Dwarfism, Pituitary - genetics; Dwarfism, Pituitary - metabolism; Endocrinology & Metabolism; Female; Fluorescent Antibody Technique; Growth Hormone-Releasing Hormone - metabolism; Growth hormone-releasing hormone receptor; Heterozygote; Humans; Isolated growth hormone deficiency; Luciferases - metabolism; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation - genetics; Pituitary hypoplasia; Polymerase Chain Reaction; Receptors, Neuropeptide - genetics; Receptors, Pituitary Hormone-Regulating Hormone - genetics; RNA Splicing; Sequence Homology, Amino Acid; Short stature; Splice donor site
• ISSN: 1096-6374; 1532-2238
• DOI: 10.1016/j.ghir.2013.03.003

Abstract Objective To elucidate the pathogenesis of isolated growth hormone (GH) deficiency in a Japanese girl without consanguinity. Design A 2-year-old girl of height 77.2 cm (− 3.0 SD for Japanese girls) was found to have an insulin-like growth factor (IGF)-1 level of 7 ng/mL and IGF binding protein-3 (IGFBP-3) level of 0.41 μg/mL. GH responded modestly to a series of pharmacological stimulants, increasing to 2.81 ng/mL with insulin-induced hypoglycemia, 3.78 ng/mL with arginine, and 3.93 with GH-releasing hormone (GHRH). Following direct sequencing of the GHRH receptor ( GHRHR ) gene, evaluation by the luciferase reporter assay, immunofluorescence study, and in vitro splicing assay with minigene constructs was conducted. Results Novel compound heterozygous GHRHR gene mutations were identified in the patient. A p.G136V substitution elicited no luciferase activity increment in response to GHRH stimulation, with normal membranous expression. Splicing assay demonstrated that the IVS2 + 3a > g mutation would lead to aberrant splicing. Conclusions A case of isolated GH deficiency due to novel GHRHR gene mutations was identified.