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. 2022 Oct 3:10:992156.
doi: 10.3389/fped.2022.992156. eCollection 2022.

Citrullinemia type I in Chinese children: Identification of two novel argininosuccinate synthetase gene mutations

Mei Xiong  1 , Mingwu Chen  1
Affiliations

Citrullinemia type I in Chinese children: Identification of two novel argininosuccinate synthetase gene mutations

Mei Xiong et al. Front Pediatr. .

Abstract

Background: In this study, we evaluated the clinical characteristics, prognosis, and gene mutations of five children with citrullinemia type I (CTLN1) diagnosed in our department and identified two novel ASS1 gene mutations.

Methods: We examined the clinical characteristics, prognosis, and gene mutations of the five children through data collection, tandem mass spectrometry, and whole-exon sequencing. MutationTaster, regSNP-intron, and SWISS-MODEL were used for bioinformatic analysis to evaluate the two novel gene mutations. We analyzed differences in blood ammonia and citrulline levels based on clinical phenotypes. Finally, we reviewed the medical literature describing Chinese children with CTLN1.

Results: ASS1 C773 + 6T > G and c.848 delA as well as c.952_953 del insTT and c.133G > A have not been previously reported in the Human Gene Mutation Database. Using MutationTaster and regSNP-intron, we predicted that these mutations affected protein function. The 3D structure obtained using SWISS-MODEL supported this prediction. Through comparative analysis showed that the ammonia level of the neonatal type was markedly higher than that of other types, whereas citrulline levels did not differ between groups.

Conclusion: We identified two novel mutations that cause disease. The blood ammonia level of neonatal form citrullinemia was markedly higher than that of other types. The genotype-phenotype association in Chinese patients remains unclear and should be further evaluated in genetic studies of larger sample sizes.

Keywords: argininosuccinate synthetase gene; citrullinemia type I; novel mutations; tandem mass spectrometry; whole-exome sequencing.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Sanger sequence of ASS1 (c.848 delA and c.773 + 6T > G) from patient 1 and her parents.
FIGURE 2
FIGURE 2
Sanger sequence of ASS1 (c.952_953 delinsTT and c.133G > A) from patient 2 and her parents.
FIGURE 3
FIGURE 3
Amino acid sequence and 3D structure. (A) Wild-type amino acid sequence of ASS1:c.848delA. (B) Mutation type amino acid sequence of ASS1:c.848delA. (C) 3D structure of wild-type of ASS1 (p.Glu283 Glyfs*13). (D) 3D structure of mutation type of ASS1(p.Glu283 Glyfs*13).
FIGURE 4
FIGURE 4
3D- structure. (A) 3D-structure of wild-type ASS1 (p.E45K,p.A318F). (B) 3D structure of mutation ASS1 (p.E45K,p.A318F). (C) 3D-structure of wild-type ASS1 (p.E45K). (D) 3D structure of mutation type ASS1 (p.E45K). (E) 3D structure of wild-type ASS1(p.A318F). (F) 3D structure mutation type ASS1 (p.A318F).
FIGURE 5
FIGURE 5
Ammonia levels in different clinical phenotypes.
FIGURE 6
FIGURE 6
Citrulline levels in different clinical phenotypes.
See this image and copyright information in PMC

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