Identification of two mutations in a compound heterozygous child with dihydrolipoamide dehydrogenase deficiency
Identification of two mutations in a compound heterozygous child with dihydrolipoamide dehydrogenase deficiency
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DOI：
10.1093/hmg/5.12.1925
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发表时间：
1996-12-01
影响因子：
3.5
通讯作者：
Patel, MS
中科院分区：
文献类型：
--
作者：
Hong, YS;Kerr, DS;Patel, MS
一名血液乳酸、丙酮酸和血浆支链氨基酸升高的女婴被诊断为二氢硫辛酰胺脱氢酶（E3;二氢硫辛酰胺：NAD（+）氧化还原酶，EC 1.8.1.4）缺乏症。患者的丙酮酸脱氢酶复合物和E3活性在血液淋巴细胞中分别为对照的26%和2%，在培养的皮肤成纤维细胞中分别为11%和14%。Western印迹分析表明，患者及其父亲的成纤维细胞中E3蛋白的量约为对照组的一半，而北方印迹分析显示E3 RNA的量正常，对患者克隆的全长E3 cDNA进行DNA测序显示，在不同的等位基因中有两个突变，一种是在前导肽序列的最后一个密码子中插入一个额外的腺嘌呤（TAC->TAAC）导致导致前体E3多肽（Y35 X）提前终止的无义突变，另一种是由于鸟嘌呤取代腺嘌呤引起的错义突变，在成熟蛋白质（R460 G）的第460位氨基酸处发生Arg → Gly取代，这可能是由于E3二聚体的结构改变而引起E3活性的丧失，来自父母的E3 cDNA的DNA测序表明，无义突变遗传自父亲，错义突变遗传自母亲。
An infant girl with elevated blood lactate, pyruvate, and plasma branched-chain amino acids was diagnosed with dihydrolipoamide dehydrogenase (E3; dihydrolipoamide: NAD(+) oxidoreductase, EC 1.8.1.4) deficiency, Activities of the pyruvate dehydrogenase complex and E3 from patient were 26 and 2% of controls in blood lymphocytes, and 11 and 14% in cultured skin fibroblasts, respectively. Western blot analysis demonstrated that the amount of E3 protein in fibroblasts from the patient and her father was about half of controls, while Northern blot analysis showed normal amounts of E3 RNA, DNA sequencing of cloned full-length E3 cDNAs from the patient revealed two mutations in separate alleles, One is a single base insertion of an extra adenine in the last codon of the leader peptide sequence (TAC-->TAAC) leading to a nonsense mutation which results in the premature termination of the precursor E3 polypeptide (Y35X), The other is a missense mutation due to substitution of guanine for adenine, causing an Arg-->Gly substitution at amino acid 460 of the mature protein (R460G) which triggers the loss of E3 activity probably by structural change in the E3 dimer, DNA sequencing of E3 cDNAs from the parents demonstrated that the nonsense mutation was inherited from the father and the missense mutation was inherited from the mother.