一例瓜氨酸血症Ⅰ型患儿的临床特点及ASS1基因突变分析
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摘要
目的对一例临床怀疑瓜氨酸血症Ⅰ型患儿进行分子遗传学研究,明确致病突变,并对其相关的临床特点、转归进行总结。方法收集患儿的临床资料,提取患儿外周血DNA,应用高通量捕获测序确定患儿ASS1基因突变情况,并用Sanger测序验证测序结果以及ASS1基因的家系分析。结果患儿生后第6天出现体温不升、呻吟、喂养困难、惊厥,血氨明显升高(1240μmol/L),血串联质谱(MS/MS)分析提示血瓜氨酸显著升高(1979.03μmol/L),尿气相色谱/质谱(GC/MS)提示乳清酸升高,予限制蛋白饮食、精氨酸治疗后血氨恢复正常,神经系统损害持续加重,头颅MRI提示脑萎缩、脑软化明显,随访至12月时死亡。基因序列分析发现患儿ASS1基因存在c.910C>T和c.1087C>T复合杂合突变,其中c.910C>T突变来源于父亲、c.1087C>T突变来源于母亲。c.910C>T突变导致第304号氨基酸由精氨酸变异为色氨酸,c.1087C>T突变导致第363号氨基酸由精氨酸变异为色氨酸,为错义突变。结论通过高通量捕获测序和Sanger测序确定了一例瓜氨酸血症Ⅰ型患儿的致病基因,随访发现该复合杂合突变引起的瓜氨酸血症患儿临床表现重,预后极差。
Objective:To study molecular genetics of a clinically suspected citrullinemia type I,to identify pathogenic mutations,and to summary clinical features and outcomes. Methods:Clinical data of the patient were collected,peripheral blood DNA was extracted,high-throughput capture sequencing was used to determine the mutation status of ASS1 gene in the patient,the sequencing results and the family analysis of ASS1 gene were verified by Sanger sequencing. Results:Hypothermia,moaning,feeding difficulties and convulsion occurred on the 6 th day after birth,blood ammonia was significantly increased(1240 μmol/L),blood tandem mass spectrometry(MS/MS)indicated that citrulline was significantly increased(1 979.03 μmol/L),and urine gas chromatography/mass spectrometry(GC/MS)indicated that orotic acid was increased. The patient received the protein restriction diet and arginine treatment,the blood ammonia returned to normal,and the neurological damage continued to worsen. Cranial MRI showed obvious brain atrophy and brain softening,and the patient died in the follow-up to 12 month. The analysis of high-throughput capture sequencing showed that c.910 C>T and c.1087 C>T heterozygous mutation in ASS1 gene,in which c.910 C>T mutation originated from the father and c.1087 C>T mutation originated from the mother. The c.910 C>T mutation leads to the mutation of no. 304 amino acid from arginine to tryptophan,and c.1087 C>T mutation leads to the mutation of no. 363 amino acid from arginine to tryptophan,all are missense mutation. Conclusion:A pathogenic gene of a patient with citrullinemia I was determined by high-throughput capture sequencing and Sanger sequencing. The patient with citrullinemia caused by this complex heterozygosis gene mutation presented severe clinical manifestations and poor prognosis.
Objective:To study molecular genetics of a clinically suspected citrullinemia type I,to identify pathogenic mutations,and to summary clinical features and outcomes. Methods:Clinical data of the patient were collected,peripheral blood DNA was extracted,high-throughput capture sequencing was used to determine the mutation status of ASS1 gene in the patient,the sequencing results and the family analysis of ASS1 gene were verified by Sanger sequencing. Results:Hypothermia,moaning,feeding difficulties and convulsion occurred on the 6 th day after birth,blood ammonia was significantly increased(1240 μmol/L),blood tandem mass spectrometry(MS/MS)indicated that citrulline was significantly increased(1 979.03 μmol/L),and urine gas chromatography/mass spectrometry(GC/MS)indicated that orotic acid was increased. The patient received the protein restriction diet and arginine treatment,the blood ammonia returned to normal,and the neurological damage continued to worsen. Cranial MRI showed obvious brain atrophy and brain softening,and the patient died in the follow-up to 12 month. The analysis of high-throughput capture sequencing showed that c.910 C>T and c.1087 C>T heterozygous mutation in ASS1 gene,in which c.910 C>T mutation originated from the father and c.1087 C>T mutation originated from the mother. The c.910 C>T mutation leads to the mutation of no. 304 amino acid from arginine to tryptophan,and c.1087 C>T mutation leads to the mutation of no. 363 amino acid from arginine to tryptophan,all are missense mutation. Conclusion:A pathogenic gene of a patient with citrullinemia I was determined by high-throughput capture sequencing and Sanger sequencing. The patient with citrullinemia caused by this complex heterozygosis gene mutation presented severe clinical manifestations and poor prognosis.
引文
[1]Woo HI,Park HD,Lee YW.Molecular genetics of citrullinemia types I and II[J].Clin Chim Acta,2014,431:1-8.DOI:10.1016/j.cca,2014,01.032.
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[3]胡平,等.新生儿瓜氨酸血症ASSl基因错义突变(C.970G>A)的分子鉴定[J].中华医学遗传学杂志,2011,28:630-633.
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[6]Kobayashi K,et al.Heterogeneity of mutations in argininosuccinate synthetase causing human citrullinemia[J].J Biol Chem,1990,265:11361-11367.PMID:2358466.
[7]温鹏强,陈占玲,王国兵,等.瓜氨酸血症患儿ASSl、ASL和SLC25A13基因的突变分析[J].中华医学遗传学杂志,2014,31(3):268-271.OI:10.3760/cma.j.issn.1003-9406.2014.03.002.
[8]谢波波,陈荣誉,王锦,等.新生儿瓜氨酸血症I型一例ASSl基因突变研究[J].中华儿科杂志,2014,52(10):788-791.DOI:10.3760/cma.j.issn.0578-1310.2014.010.015.
[9]孙云,马定远,杨贵江,等.一例瓜氨酸血症临床特征及ASSl基因突变分析[J].中华医学遗传学杂志,2015,32(5):745-747.DOI:10.3760/cma.J.issn.1003-9406.2015.05.030.
[10]沈玉燕.新生儿瓜氨酸血症Ⅰ型一例[J].中国优生与遗传杂志,2018,26(5):87-88.DOI:10.13404/j.cnki.cjbhh.2018.05.035.
[11]杨艳玲,孙芳,钱宁,等.尿素循环障碍的临床和实验室筛查研究[J].中华儿科杂志,2005,43(5):331-334.
[2]Haberle J,et al.Structure of the human argininosuccinate synthetase gene and an improved system for molecular diagnostics in patients with classical and mild citrullinemia[J].Hum Genet,2002,110:327-333.DOI:10.1007/s00439-002-0686-6.
[3]胡平,等.新生儿瓜氨酸血症ASSl基因错义突变(C.970G>A)的分子鉴定[J].中华医学遗传学杂志,2011,28:630-633.
[4]Gao HZ,Kobayashi K,Tabata A,et al.Identification of 16 novel mutations in the argininosuccinate synthetase gene and genotypephenotype correlation in 38 classical citrullinemia patients[J].Hum Mutat,2003,22:24-34.DOI:10.1002/humu.10230.
[5]Lee BH,Kim YM,Heo SH,et al.High prevalence of neonatal presentation in Korean patients with citrullinemia type 1,and their shared mutations[J].Mol Genet Metab,2013,108:18-24.DOI:I CTLN1 MIM#21570000 1116 3-165 12-14c.910C>Tc.1087C>T 36310.1016/j.ymgme.2012.11.011.
[6]Kobayashi K,et al.Heterogeneity of mutations in argininosuccinate synthetase causing human citrullinemia[J].J Biol Chem,1990,265:11361-11367.PMID:2358466.
[7]温鹏强,陈占玲,王国兵,等.瓜氨酸血症患儿ASSl、ASL和SLC25A13基因的突变分析[J].中华医学遗传学杂志,2014,31(3):268-271.OI:10.3760/cma.j.issn.1003-9406.2014.03.002.
[8]谢波波,陈荣誉,王锦,等.新生儿瓜氨酸血症I型一例ASSl基因突变研究[J].中华儿科杂志,2014,52(10):788-791.DOI:10.3760/cma.j.issn.0578-1310.2014.010.015.
[9]孙云,马定远,杨贵江,等.一例瓜氨酸血症临床特征及ASSl基因突变分析[J].中华医学遗传学杂志,2015,32(5):745-747.DOI:10.3760/cma.J.issn.1003-9406.2015.05.030.
[10]沈玉燕.新生儿瓜氨酸血症Ⅰ型一例[J].中国优生与遗传杂志,2018,26(5):87-88.DOI:10.13404/j.cnki.cjbhh.2018.05.035.
[11]杨艳玲,孙芳,钱宁,等.尿素循环障碍的临床和实验室筛查研究[J].中华儿科杂志,2005,43(5):331-334.