Feigerlova E, Swinyard M, Derr MA, Farnsworth J, Andrew SF, Rosenfeld RG, Hwa V. A novel GHR intronic variant, c.266+83G>T , activates a cryptic 5' splice site causing severe GHR deficiency and classical GH insensitivity syndrome.
Horm Res Paediatr 2014;
80:397-405. [PMID:
24296660 DOI:
10.1159/000355404]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/24/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS
Mutations in the human growth hormone receptor gene (GHR) are the most common cause of growth hormone insensitivity (GHI) syndrome and insulin-like growth factor (IGF-1) deficiency. The extracellular domain of GHR (encoded by exons 2-7 of the GHR gene) can be proteolytically cleaved to circulate as GH-binding protein (GHBP).
METHODS
We evaluated the cause of classical GHI (Laron) phenotypes in 3 siblings.
RESULTS
Two brothers (aged 16.5 and 14.9 years) and their half-brother (aged 11.3 years) presented with extreme short stature (height standard deviation score, SDS, of -7.05, -6.34 and -8.02, respectively). The parents were consanguineous and of normal stature. Serum GHBP levels of probands were undetectable and circulating IGF-1 and IGF-binding protein-3 were abnormally low, but GH concentrations were elevated. Molecular analysis of the GHR gene revealed homozygous deletion of exon 3, a common polymorphism, and a novel c.266+83G>T variant within intron 4 which generated a 5' donor splice site. Splicing events from this cryptic 5' donor site resulted in retention of 81 intronic nucleotides in the GHR mRNA. Long-term rhIGF-1 therapy combined with leuprolide depot increased height by +2 to +3 SDS.
CONCLUSION
The c.266+83G>T is the second intronic GHR mutation identified that activates a cryptic 5' donor splice site. The abnormal splicing event led to early protein termination and undetectable serum GHBP concentrations. © 2013 S. Karger AG, Basel.
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