OBJECTIVE: To analyze the clinical and genetic characteristics of three Chinese pedigrees affected with Citrullinemia type I (CTLN1). METHODS: Three children diagnosed at the Children's Hospital Affiliated to Shandong University from 2017 to 2020 were selected as the study subjects. Genomic DNA was extracted from peripheral blood samples of the probands and their parents. Next generation sequencing (NGS) was carried out to detect pathological variants of the probands. Sanger sequencing was used for validating the candidate variant among the pedigrees. RESULTS: The probands have respectively carried compound heterozygous variants of c.207_209delGGA and c.1168G>A, c.349G>A and c.364-1G>A, c.470G>A and c.970G>A of the ASS1 gene, which were respectively inherited from their parents. CONCLUSION The newly discovered c.207_209delGGA and c.364-1G>A variants have enriched the mutational spectrum of the ASS1 gene. And the mutation spectrum of Chinese CTLN1 patients is heterogeneous.
Child ; Humans ; Argininosuccinate Synthase/genetics* ; Citrullinemia/genetics* ; East Asian People ; Mutation ; Pedigree

OBJECTIVE: To explore the clinical and genetic features of an infant with citrin deficiency (CD). METHODS: Clinical data of the patient was collected and analyzed. Genomic DNA was extracted from peripheral blood samples collected from the patient and her parents. Targeted exome sequencing was performed to explore the genetic cause, and Sanger sequencing was used to confirm the detected variants. SLC25A13 mRNA was extracted from peripheral blood lymphocytes of the infant. The effect of novel mutation of SLC25A13 was analyzed by reverse transcription-PCR, cDNA cloning and Sanger sequencing. RESULTS: The SLC25A13 genotype of the patient was determined as c.845_c.848+1delG/c.1841+3_1841+4delAA, with the latter having not been reported. The mutation has affected the splicing of the SLC25A13 mRNA, giving rise to an aberrant transcript [r.1841_1842ins1841+1_1841+67; 1841+3_c.1841+4del]. CONCLUSION A novel SLC25A13 mutation c.1841+3_1841+4delAA and the resultant abnormal splicing variant were discovered by combined DNA sequencing and cDNA cloning. The finding has enabled definite diagnosis of CD and enriched the spectrum of SLC25A13 mutations.
Base Sequence ; Citrullinemia ; Female ; Humans ; Mitochondrial Membrane Transport Proteins ; genetics ; Mutation ; Pedigree

OBJECTIVETo identify the genetic mutation in ASS1 gene in a Chinese family with citrullinemia typeI, which may provide a basis for the diagnosis and genetic counseling.

METHODGenomic DNA was isolated from peripheral blood samples of the family members. Mutation analysis of ASS1 gene was carried out by PCR and Sanger sequencing. Biostructural analysis of the mutated ASS1 was completed by Phyre server.

RESULTDouble heterozygous mutations in the proband were identified: c.951delT (F317LfsX375) and c.1087C>T (R363W), which were confirmed in the proband's father and mother, respectively. It was found that the c.951delT mutation might change the formation of a dimer or a tetramer and the function of ASS1 protein.

CONCLUSIONDouble heterozygous mutations for c.951delT and c.1087C>T have been found in a proband with citrullinemia typeI. The c.951delT is a novel mutation in citrullinemia typeI, which may change the configuration of ASS1 protein and result in ASS1 dysfunction.

Argininosuccinate Synthase ; genetics ; Asian Continental Ancestry Group ; genetics ; Citrullinemia ; genetics ; DNA Mutational Analysis ; Humans ; Infant, Newborn ; Mutation

OBJECTIVE: To explore the clinical characteristics and genetic findings of patients with infantile intrahepatic cholestasis. METHODS: The clinical data were collected in children who were admitted to the Department of Gastroenterology in Children's Hospital, Capital Institute of Pediatrics from June 2017 to June 2019 and were suspected of inherited metabolic diseases. Next generation sequencing based on target gene panel was used for gene analysis in these children. Sanger sequencing technology was used to verify the genes of the members in this family. RESULTS: Forty patients were enrolled. Pathogenic gene variants were identified in 13 patients (32%), including CONCLUSIONS The etiology of infantile intrahepatic cholestasis is complex. Next generation sequencing is helpful in the diagnosis of infantile intrahepatic cholestasis.
Alagille Syndrome/genetics* ; Child ; Cholestasis, Intrahepatic/genetics* ; Citrullinemia ; Genetic Testing ; High-Throughput Nucleotide Sequencing ; Humans ; Mitochondrial Membrane Transport Proteins ; Mutation

OBJECTIVE: To explore the characteristics of SLC25A13 gene variants in 16 infants with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). METHODS: The infants were subjected to high-throughput DNA sequencing for coding exons and flanking regions of the target genes. Suspected variants were verified by Sanger sequencing and bioinformatic analysis. RESULTS: Among the 16 NICCD cases, 15 were found to harbor pathogenic variants. Among these, IVS14-9A>G, c.1640G>A, c.762T>A, c.736delG, c.1098Tdel and c.851G>A were previously unreported. CONCLUSION Six novel SLC25A13 variants were found by high-throughput sequencing, which has enriched the spectrum of SLC25A13 gene variants and provided a basis for genetic counseling and prenatal diagnosis.
Calcium-Binding Proteins/genetics* ; Cholestasis, Intrahepatic/genetics* ; Citrullinemia/genetics* ; Humans ; Infant ; Infant, Newborn ; Mitochondrial Membrane Transport Proteins/genetics* ; Mutation ; Organic Anion Transporters/genetics* ; Protein Deficiency

Citrin is a liver-type mitochondrial aspartate-glutamate carrier encoded by the SLC25A13 gene, and its deficiency causes adult-onset type II citrullinemia and neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). Here, the authors investigated clinical findings in Korean infants with NICCD and performed mutation analysis on the SLC25A13 gene. Of 47 patients with neonatal cholestasis, three infants had multiple aminoacidemia (involving citrulline, methionine, and arginine) and galactosemia, and thus were diagnosed as having NICCD. Two of these three showed failure to thrive. The laboratory findings showed hypoproteinemia and hyperammonemia, and liver biopsies revealed micro-macrovesicular fatty liver and cholestasis. The three patients each harbored compound heterozygous 1,638-1,660 dup/ S225X mutation, compound heterozygous 851del4/S225X mutation, and heterozygous 1,638-1,660 dup mutation, respectively. With nutritional manipulation, liver functions were normalized and catch-up growth was achieved. NICCD should be considered in the differential diagnosis of cholestatic jaundice in Korean infants.
Amino Acids/blood ; Calcium-Binding Proteins/*deficiency ; Cholestasis, Intrahepatic/*etiology/genetics ; Citrullinemia/genetics ; Humans ; Infant ; Membrane Transport Proteins/genetics ; Mitochondrial Proteins/genetics ; Mutation ; Organic Anion Transporters/*deficiency

OBJECTIVETo detect potential mutations in six patients with citrullinemia.

METHODSGenomic DNA was extracted from peripheral blood samples from the patients. Mutations of the ASS1, ASL and SLC25A13 genes were screened using microarray genotyping combined with direct sequencing.

RESULTSOne patient was diagnosed with argininosuccinate lyase deficiency, and has carried a homozygous c.1311T>G (p.Y437*) mutation of the ASL gene. The remaining five patients were diagnosed with neonatal intrahepatic cholestasis due to citrin deficiency, and have respectively carried mutations of the SLC25A13 gene including [c.851-854delGTAT+c.851-854delGTAT], [c.851-854delGTAT+IVS6+5G>A], [c.851-854delGTAT+IVS16ins3kb], [c.851-854delGTAT+IVS6-11A>G] and [c.851-854delGTAT+c.1638-1660dup23]. Among these, the c.1311T>G mutation was first identified in the Chinese population, and the IVS6-11A>G mutation was a novel variation which may affect the splicing, as predicted by Human Splicing Finder software.

CONCLUSIONThis study has confirmed the molecular diagnosis of citrullinemia in six patients and expanded the mutational spectrum underlying citrullinemia.

Argininosuccinate Lyase ; genetics ; Argininosuccinate Synthase ; genetics ; Citrullinemia ; genetics ; DNA Mutational Analysis ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Mitochondrial Membrane Transport Proteins ; genetics ; Mutation

Citrin deficiency causes autosomal recessive disorders including adult-onset type II citrullinemia (CTLN2) and neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). The responsive gene of citrin deficiency, SLC25A13, locates on chromosome 7q21.3 and encodes citrin as a liver-type mitochondrial aspartate/glutamate carrier (AGC). The mutations on SLC25A13 will result in deficiency of citrin and CTLN2 or NICCD. Citrin deficiency was found at first in Japan. However, recently, some of cases were identified in China, Korea, Vietnam, Israel, Czech, United States and England, and racial differences of the SLC25A13 mutations were found, suggesting the patients with citrin deficiency maybe exist worldwide. In this article, authors reviewed the progresses in the study on citrin deficiency up to now and put forward authors' considerations for further research on it.
Animals ; Calcium-Binding Proteins ; deficiency ; genetics ; Cholestasis, Intrahepatic ; genetics ; surgery ; Chromosomes, Human, Pair 7 ; Citrullinemia ; etiology ; genetics ; surgery ; Humans ; Liver Transplantation ; Membrane Transport Proteins ; genetics ; Mitochondrial Membrane Transport Proteins ; Mitochondrial Proteins ; genetics ; Organic Anion Transporters ; deficiency ; genetics ; Point Mutation

OBJECTIVETo detect potential mutations of Y9ASS1, ASL and SLC25A13 genes in four patients manifesting citrullinemia.

METHODSGenomic DNA was extracted from peripheral blood leukocytes. Exons and their flanking sequences of the three genes were amplified with polymerase chain reaction and subjected to direct DNA sequencing.

RESULTSBased on DNA sequence analysis, one case was diagnosed with argininosuccinate synthetase deficiency, and the mutation type (ASS1 gene) was c.236C>T (p.S79F) + c.431C>G (p.P144R). Two cases were diagnosed with argininosuccinic aciduria (ASL gene), and their gene mutations were c.434A>G (p.D145G) + c.1366C>T (p.R456W) and c.331C>T (p.R111W) + IVS8+2insT, respectively. A thirteen months boy who carried a heterozygous 851del4 mutation (SLC25A13 gene) was diagnosed with citrullinemia adult-onset type II.

CONCLUSIONThrough analysis of relevant pathogenic genes, four patients have been diagnosed.

Adult ; Amino Acid Sequence ; Argininosuccinate Lyase ; genetics ; metabolism ; Argininosuccinate Synthase ; genetics ; metabolism ; Base Sequence ; Citrullinemia ; enzymology ; genetics ; Female ; Humans ; Infant ; Male ; Mitochondrial Membrane Transport Proteins ; genetics ; metabolism ; Molecular Sequence Data ; Pedigree ; Point Mutation

OBJECTIVETo assess the feasibility of high-resolution melting (HRM) analysis for screening patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD).

METHODSBased on previous studies on SLC25A13 gene in Chinese patients with NICCD, four hotspot mutations (851del4, 1638ins23, IVS6+5G>A and IVS16ins3kb) were selected. Results of the HRM analysis was validated using 50 negative controls and 20 patients with NICCD whose genotypes were confirmed previously by direct sequencing. With the established protocol, 171 suspected patients were enrolled. Samples with abnormal melting curves were further validated by DNA sequencing.

RESULTSHRM analysis can accurately determine the genotypes of all negative controls and patients. The sensitivity and specificity of the technique reached 100% (70/70). The melting curves of samples with the same genotype were highly reproducible. In 171 suspected patients, seven NICCD patients were detected by HRM. Identified mutations have included one case of 851del4 homozygote, one case of IVS6+5G>A heterozygote, 3 cases of 851del4 heterozygotes, one case of [IVS6+5G>A]+[ 851del4] and one case of [1638ins23+IVS16ins3kb]+[1638ins23]. All mutations were subsequently confirmed by DNA sequencing.

CONCLUSIONHRM analysis is a convenient, high-throughput and rapid technique for the screening of NICCD patients.

Anion Transport Proteins ; genetics ; Base Sequence ; Calcium-Binding Proteins ; deficiency ; China ; Citrullinemia ; diagnosis ; genetics ; metabolism ; DNA ; chemistry ; genetics ; Genetic Predisposition to Disease ; Genotype ; Humans ; Mitochondrial Proteins ; genetics ; Molecular Sequence Data ; Mutation ; Nucleic Acid Denaturation ; Organic Anion Transporters ; deficiency ; Sensitivity and Specificity