Growth hormone (GH1
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- 作者：David S. Millar ; Mark D. Lewis ; Martin Horan ; Vicky Newsway ; D. Aled Rees ; Tammy E. Easter ; Guglielmina Pepe ; Olga Rickards ; Martin Norin ; Maurice F. Scanlon ; Michael Krawczak ; David N. Cooper
- 关键词：Growth hormone ; Growth hormone receptor ; Benin ; Missense mutations ; Promoter haplotype ; Gene conversion ; Gene expression
- 刊名：Molecular and Cellular Endocrinology
- 出版年：2008
- 出版时间：16 December 2008
- 年：2008
- 卷：296
- 期：1-2
- 页码：18-25
- 全文大小：339 K
文摘
Among Europeans, functionally significant GH1 gene variants occur not only in individuals with idiopathic growth hormone (GH) deficiency and/or short stature but also fairly frequently in the general population. To assess the generality of these findings, 163 individuals from Benin, West Africa were screened for mutations and polymorphisms in their GH1 genes. A total of 37 different sequence variants were identified in the GH1 gene region, 24 of which occurred with a frequency of >1 % . Although four of these variants were novel missense substitutions (Ala13Val, Arg19His, Phe25Tyr and Ser95Arg), none of these had any measurable effect on either GH function or secretion in vitro. Some 37 different GH1 promoter haplotypes were identified, 23 of which are as yet unreported in Europeans. The mean in vitro expression level of the GH1 promoter haplotypes observed in the African population was significantly higher than that previously measured in Britons (p < 0.001). A gene conversion in the GH1 promoter, previously reported in a single individual of British origin, was found to occur at polymorphic frequency (5 % ) in the West-African population and was associated with a 1.7-fold increase in promoter activity relative to the wild-type. The d3 allele of the GHR exon 3 deletion polymorphism, known to be associated with increased GH responsiveness, was also found to occur at an elevated frequency in these individuals from Benin. We speculate that both elevated GH1 gene expression and increased GHR-mediated GH responsiveness may constitute adaptive responses to the effects of scarce food supply in this West-African population since increased circulating GH appears to form part of a physiological response to nutritional deprivation.