Identification of novel missense mutations (Phe310Leu and Gly439Arg) in a neonatal case of hypophosphatasia
Identification of novel missense mutations (Phe310Leu and Gly439Arg) in a neonatal case of hypophosphatasia
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DOI：
10.1210/jc.81.12.4458
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发表时间：
1996-12-01
影响因子：
5.8
通讯作者：
Nakayama, M
中科院分区：
文献类型：
--
作者：
Ozono, K;Yamagata, M;Nakayama, M
低磷酸酶症与组织非特异性碱性磷酸酶基因缺陷有关。我们对一名出生时诊断为低磷酸酶症的存活患者进行了突变分析，该患者的基础是血清碱性磷酸酶（ALP）活性水平低和特征性X线检查结果。她有两个姐妹篇，其中一个死于呼吸衰竭并发围产期低磷酸酶症;另一个看起来很健康，ALP活性水平相对较低。患者的父母也有低ALP活性。组织非特异性碱性磷酸酶基因的序列分析进行，使用基因组DNA和总RNA从皮肤成纤维细胞的患者和外周血单核细胞的她的父母。在患者中鉴定了Phe在密码子310处（F310 L）转化为Leu和Gly在密码子439处（G439 R）转化为Arg。有趣的是，重建实验表明，F310 L突变体表现出的ALP活性水平为正常水平的65%，而突变体G439 R没有活性。此外，在使用从患者的成纤维细胞和她父亲的淋巴细胞提取的互补DNA进行PCR后，通过StuI消化，显示了相对低的F310 L信使RNA水平。这些结果表明，新生儿低磷酸酶症病例与复合突变有关，其中一种突变导致ALP活性丧失，另一种突变导致ALP活性轻微降低，信使RNA水平相对较低。
Hypophosphatasia is associated with a defect of the tissue-nonspecific alkaline phosphatase gene. We performed a mutational analysis in a surviving patient diagnosed at birth as having hypophosphatasia, on the basis of a low level of serum alkaline phosphatase (ALP) activity and characteristic radiographical findings. She had two sisters, one of whom died of respiratory failure complicated by perinatal hypophosphatasia; the other seemed healthy, with a relatively low activity level of ALP. The patient's parents also had low ALP activity. Sequence analysis of the tissue-nonspecific alkaline phosphatase gene was performed, using genomic DNA and total RNA from the skin fibroblasts of the patient and the peripheral mononuclear cells of her parents. The conversion of Phe to Leu at codon 310 (F310L) and Gly to Arg at 439 (G439R) were identified in the patient. Interestingly, the reconstructive experiments demonstrated that the F310L mutant exhibited an ALP activity level 65% of the normal level, whereas the mutant G439R had no activity. Moreover, the digestion by StuI, after a PCR using complementary DNA extracted from fibroblasts of the patient and lymphocytes of her father, revealed a relatively low messenger RNA level of F310L. These findings suggest that the neonatal case of hypophosphatasia was associated with compound mutations, one of which caused the loss of ALP activity and the other of which caused a slight reduction of the ALP activity, with a relatively low level of messenger RNA.