title: Identification of a novel splicing mutation in the growth hormone (GH)-releasing hormone receptor gene in a Chinese family with pituitary dwarfism.
abstract: A Chinese family with autosomal recessive pituitary dwarfism was identified and the proband was evaluated by MRI and hormonal analysis, which revealed pituitary dwarfism with a complete growth hormone deficiency. MRI showed a pituitary gland with a small anterior pituitary of 2.2mm and evidence of hypoplastic pituitary. Linkage analysis with markers spanning 17 known genes for dwarfism revealed linkage of the family to the growth hormone-releasing hormone receptor (GHRHR) gene. Mutational analysis of all exons and exon-intron boundaries of GHRHR was carried out using direct DNA sequence analysis. A novel homozygosis mutation, a G to A transition located in the splice donor site at the beginning of intron 8 (IVS8+1G>A), was identified in the proband. The two other patients in the family are homozygous, whereas the living mother of the proband is heterozygous for the IVS8+1G>A mutation. The mutation was not found in 100 normal chromosomes from healthy Chinese individuals of Han nationality. An in vitro splicing assay using HeLa cells transfected with expression vectors containing the normal or the mutant GHRHR minigenes consisting of genomic fragments spanning exons 7-9 showed that the IVS8+1G>A mutation caused abnormal splicing, which is predicted to give rise to truncation or frameshift, leading to severely truncated GHRHR proteins. These results provide strong evidence that the splicing mutation IVS8+1G>A of GHRHR is a cause of pituitary dwarfism in the Chinese family.
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Center for Human Genome Research, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Diao
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Xu
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Li
authors.forename: Xiao Ping
authors.initials: XP
authors.lastname: Luo
authors.forename: Haibo
authors.initials: H
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Ouyang
authors.forename: Mugen
authors.initials: M
authors.lastname: Liu
authors.forename: Zhongli
authors.initials: Z
authors.lastname: Hu
authors.forename: Qing K
authors.initials: QK
authors.lastname: Wang
authors.forename: Jing Yu
authors.initials: JY
authors.lastname: Liu
mesh_terms: D017398:Alternative Splicing; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D004252:DNA Mutational Analysis; D004393:Dwarfism, Pituitary / Q000235:genetics*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D010902:Pituitary Gland / Q000378:metabolism / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics*; D022821:RNA Splice Sites / Q000235:genetics; D018013:Receptors, Neuropeptide / Q000235:genetics*; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics*
chemical_list: D020033:Protein Isoforms; D022821:RNA Splice Sites; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; C048250:somatotropin releasing hormone receptor