Johnston L B, Pashankar F, Camacho-Hübner C, Savage M O, Clark A J
Molecular Endocrinology Laboratory and Paediatric Endocrine Section, St Bartholomew's Hospital, London, UK.
Clin Endocrinol (Oxf). 2000 Apr;52(4):463-9. doi: 10.1046/j.1365-2265.2000.00940.x.
To investigate the hypothesis that intracellular, dominant-negative mutations of the growth hormone receptor (GHR) exist in children with idiopathic short stature (ISS) and partial growth hormone insensitivity (GHI).
We studied 31 children aged 4.55-13.14 years with ISS (height </= -1.8 standard deviation scores, UK standards 1990). GH provocation tests (glucagon 15 microg kg-1 i.m.) excluded GH deficiency in all subjects. Serum IGF-I levels were below the 50th centile for age in all subjects and below the 10th centile in 64.5% of cases. GH binding protein levels were normal in the 24 subjects in whom it was measured (mean 25.2%; range 10-42.6%).
Exons 9 and 10 of the GHR were amplified by PCR from leucocyte-derived DNA. Samples were directly sequenced on the ABI 377 DNA analyser using the - 21 M13 dye primer cycle sequencing protocol for optimum heterozygote detection.
No abnormalities were detected in exon 9 which encodes the proline-rich box 1 motif. In exon 10 two sequence variants were found; a heterozygous, single base alteration (TCT to TCC) in codon 325 which does not change the amino acid sequence in one patient, and the L526I variant in 24 subjects. L526I is a conservative amino acid change and had an allele frequency of 0.53 in our patients, which is similar to that reported in a control population.
The apparent partial growth hormone insensitivity in this group of idiopathic short-stature subjects is not related to heterozygous, dominant-negative variants of the intracellular signalling domain of the GHR. Hence it is likely that other genetic and environmental factors may be involved.
探讨特发性身材矮小（ISS）和部分生长激素不敏感（GHI）儿童是否存在生长激素受体（GHR）细胞内显性负性突变的假说。
我们研究了31名年龄在4.55至13.14岁之间的ISS儿童（身高≤ -1.8标准差评分，英国1990年标准）。生长激素激发试验（胰高血糖素15μg/kg皮下注射）排除了所有受试者的生长激素缺乏。所有受试者的血清胰岛素样生长因子-I（IGF-I）水平均低于年龄的第50百分位数，64.5%的病例低于第10百分位数。在所检测的24名受试者中，生长激素结合蛋白水平正常（平均25.2%；范围10 - 42.6%）。
从白细胞来源的DNA中通过聚合酶链反应（PCR）扩增GHR的外显子9和10。使用 - 21 M13染料引物循环测序方案在ABI 377 DNA分析仪上对样品进行直接测序，以实现最佳杂合子检测。
在编码富含脯氨酸盒1基序的外显子9中未检测到异常。在外显子10中发现了两个序列变异；一名患者密码子325处的杂合单碱基改变（TCT变为TCC），氨基酸序列未改变，以及24名受试者中的L526I变异。L526I是保守的氨基酸变化，在我们的患者中其等位基因频率为0.53，与对照人群中报道的相似。
这组特发性身材矮小受试者中明显的部分生长激素不敏感与GHR细胞内信号传导域的杂合显性负性变异无关。因此，可能涉及其他遗传和环境因素。
