Hong Y S, Kerr D S, Liu T C, Lusk M, Powell B R, Patel M S
Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo 14214, USA.
Biochim Biophys Acta. 1997 Dec 31;1362(2-3):160-8. doi: 10.1016/s0925-4439(97)00073-2.
A male child with metabolic acidosis was diagnosed as having dihydrolipoamide dehydrogenase (E3) deficiency. E3 activity of the proband's cultured fibroblasts and blood lymphocytes was 3-9% of normal, while in the parent's lymphocytes it was about 60% of normal. The proband's pyruvate dehydrogenase complex (PDC) and the alpha-ketoglutarate dehydrogenase complex activities from cultured skin fibroblasts were 12% and 6% of normal, respectively. PDC activity in the parents cultured fibroblasts was 25-31% of normal. Western and Northern blot analyses showed similar quantities of E3 protein and mRNA in cultured fibroblasts from the proband and his parents. DNA sequencing of cloned full-length E3 cDNAs, from the proband and the parents, showed two mutations on different alleles of proband were inherited from the parents. One mutation is a three nucleotide (AGG) deletion, from the mother, resulting in deletion of Gly101 in the FAD binding domain. The other mutation is a nucleotide substitution (G to A), from the father, leading to substitution of Lys for Glu340 in the central domain. The same deletion mutation was found in E3 cDNA from a chorionic villus sample and cultured fibroblasts obtained from the mother's subsequent offspring. This finding illustrates the possibility of successful prenatal diagnosis of E3 deficiency utilizing mutations characterized prior to initiation of pregnancy.
一名患有代谢性酸中毒的男童被诊断为二氢硫辛酰胺脱氢酶（E3）缺乏症。先证者培养的成纤维细胞和血液淋巴细胞的E3活性为正常水平的3%-9%，而其父母淋巴细胞中的E3活性约为正常水平的60%。先证者培养的皮肤成纤维细胞中的丙酮酸脱氢酶复合物（PDC）和α-酮戊二酸脱氢酶复合物活性分别为正常水平的12%和6%。其父母培养的成纤维细胞中的PDC活性为正常水平的25%-31%。蛋白质免疫印迹法和Northern印迹法分析显示，先证者及其父母培养的成纤维细胞中E3蛋白和mRNA的量相似。对先证者及其父母克隆的全长E3 cDNA进行DNA测序，结果显示先证者不同等位基因上的两个突变是从父母那里遗传来的。一个突变是来自母亲的三个核苷酸（AGG）缺失，导致FAD结合域中的Gly101缺失。另一个突变是来自父亲的核苷酸替换（G突变为A），导致中央结构域中的Glu340被Lys取代。在来自绒毛膜绒毛样本的E3 cDNA以及从母亲随后的后代获得的培养成纤维细胞中发现了相同的缺失突变。这一发现说明了利用妊娠开始前鉴定出的突变成功进行E3缺乏症产前诊断的可能性。
