Clinical characteristics and genetic analysis of a child with Galactosemia due to compound heterozygous variants ofGALT gene
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目的 分析1例GALT基因变异所致的半乳糖血症患儿的临床及遗传学特点。 方法 以2019年11月20日就诊于郑州大学附属儿童医院的1例患儿作为研究对象。收集其临床资料，并对其进行全外显子组测序分析，对候选变异进行Sanger测序家系验证。 结果 患儿表现为贫血、喂养困难、黄疸、肌张力低下、肝功能异常、凝血功能异常等。血氨基酸及酰基肉碱谱显示瓜氨酸、蛋氨酸、鸟氨酸、酪氨酸水平升高。尿有机酸分析显示苯乳酸、4-羟基苯乙酸、4-羟基苯乳酸、4-羟基苯丙酮酸、N-乙酰酪氨酸水平升高。基因检测显示患儿GALT基因存在c.627T>A(p.Y209*)和c.370G>C(p.G124R)复合杂合变异，分别遗传自其表型正常的父母。前者为已报道的无义变异，依据美国医学遗传学与基因组学学会(ACMG)相关指南判断为可能致病性变异；后者为未见报道的错义变异，依据ACMG相关指南判断为可能致病性变异(PM1+PM2_Supporting+PP3_Moderate+PP4)。 结论 GALT基因c.627T>A(p.Y209*)和c.370G>C(p.G124R)复合杂合变异可能是患儿半乳糖血症的遗传学病因。上述发现扩展了GALT基因的变异谱。对无明显诱因出现贫血、喂养困难、黄疸、肝功能异常和凝血功能异常等症状的患者，应尽早行血尿代谢筛查，结合基因检测进行确诊。 Objective To explore the clinical features and genetic basis of a child with Galactosemia. Methods A child who had presented at the Children′s Hospital Affiliated to Zhengzhou University on November 20, 2019 was selected as the study subject. Clinical data of the child was collected. Whole exome sequencing was carried out for the child. Candidate variants were validated by Sanger sequencing. Results Clinical manifestations of the child have included anemia, feeding difficulty, jaundice, hypomyotonia, abnormal liver function and coagulation abnormality. Tandem mass spectrometry showed increased citrulline, methionine, ornithine and tyrosine. Urine organic acid analysis showed increased phenyllactic acid, 4-hydroxyphenylacetic acid, 4-hydroxyphenyllactic acid, 4-hydroxyphenylpyruvate and N-acetyltyrosine. Genetic testing revealed that the child has harbored compound heterozygous variants of the GALT gene, namely c. 627T>A (p.Y209*) and c. 370G>C (p.G124R), which were respectively inherited from her healthy parents. Among these, c. 627T>A (p.Y209*) was known as a likely pathogenic variant, while c. 370G>C (p. G124R) was unreported previously and also predicted as a likely pathogenic variant(PM1+ PM2_Supporting+ PP3_Moderate+ PP4). Conclusion Above discovery has expanded the spectrum of the GALT gene variants underlying Galactosemia. Patients with thrombocytopenia, feeding difficulties, jaundice, abnormal liver function and coagulation abnormality without obvious causes should be analyzed by screening of metabolic diseases in combination with genetic testing.
Objective To explore the clinical features and genetic basis of a child with Galactosemia. Methods A child who had presented at the Children′s Hospital Affiliated to Zhengzhou University on November 20, 2019 was selected as the study subject. Clinical data of the child was collected. Whole exome sequencing was carried out for the child. Candidate variants were validated by Sanger sequencing. Results Clinical manifestations of the child have included anemia, feeding difficulty, jaundice, hypomyotonia, abnormal liver function and coagulation abnormality. Tandem mass spectrometry showed increased citrulline, methionine, ornithine and tyrosine. Urine organic acid analysis showed increased phenyllactic acid, 4-hydroxyphenylacetic acid, 4-hydroxyphenyllactic acid, 4-hydroxyphenylpyruvate and N-acetyltyrosine. Genetic testing revealed that the child has harbored compound heterozygous variants of the GALT gene, namely c. 627T>A (p.Y209*) and c. 370G>C (p.G124R), which were respectively inherited from her healthy parents. Among these, c. 627T>A (p.Y209*) was known as a likely pathogenic variant, while c. 370G>C (p. G124R) was unreported previously and also predicted as a likely pathogenic variant(PM1+ PM2_Supporting+ PP3_Moderate+ PP4). Conclusion Above discovery has expanded the spectrum of the GALT gene variants underlying Galactosemia. Patients with thrombocytopenia, feeding difficulties, jaundice, abnormal liver function and coagulation abnormality without obvious causes should be analyzed by screening of metabolic diseases in combination with genetic testing.
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