OBJECTIVE: To explore the genetic basis of a neonate with argininosuccinic aciduria (ASA). METHODS: A neonate with lethargy and food refusal was admitted. The patient had myoclonus, myasthenia, uroschesis, irregular breathing and paroxysmal ventricular tachycardia, and died at 75 hours after birth. Laboratory test showed marked increase in blood ammonia (1249.8 μmol/L). Peripheral blood samples of the patient, her parents and sister were collected and subjected to trio whole-exome sequencing. RESULTS: Whole-exome sequencing revealed that the patient has carried compound heterozygous mutations of the argininosuccinate lyase (ASL) gene, namely c.425(exon5)_c.426(exon5) insAGCTCCCAGCT (p.Thr142Thrfs*37) and c.626(exon8)delT (p.Leu209Argfs*42). The patient was diagnosed as ASA caused by ASL gene mutations. Her parents and her elder sister were heterozygous carriers of the above mutations and had a normal phenotype. CONCLUSION ASA is a severe congenital genetic metabolic disease and can manifest as onset of hyperammonemia in neonates. The clinical diagnosis is difficult and ASL gene testing may be helpful.
Argininosuccinate Lyase ; genetics ; Argininosuccinic Aciduria ; diagnosis ; genetics ; Female ; Genetic Testing ; Humans ; Hyperammonemia ; Infant, Newborn ; Pedigree

OBJECTIVES: Primary carnitine deficiency (PCD) is a rare fatty acid metabolism disorder that can cause neonatal death. This study aims to analyze carnitine levels and detect SLC22A5 gene in newborns with carnitine deficiency, to provide a basis for early diagnosis of PCD, and to explore the relationship between carnitine in blood and SLC22A5 genotype. METHODS: A total of 40 neonates with low free carnitine (C0<10 μmol/L) in blood were the subjects of the study. SLC22A5 gene was detected by Sanger sequencing to analyze the value of carnitine, the results of gene test and their relationship. RESULTS: A total of 15 variants of SLC22A5 gene were detected, including 11 pathogenic or likely pathogenic variants and 4 variants of uncertain significance. There were 5 new mutations: c.288delG (p.G96fsX33), c.744_745insTCG (p.M258_L259insS), c.752A>G (p.Y251C), c.495 C>A (p.R165E), and c.1298T>C (p.M433T). We found 14 PCD patients including 2 homozygous mutations and 12 heterozygous mutations, 14 with 1 mutation, and 12 with no mutation among 40 children. The C0 concentration of children with SLC22A5 gene homozygous or complex heterozygous mutations was (4.95±1.62) μmol/L in the initial screening, and (3.90±1.33) μmol/L in the second screening. The C0 concentration of children with no mutation was (7.04±2.05) μmol/L in the initial screening, and (8.02±2.87) μmol/L in the second screening. There were significant differences between children with homozygous or compound heterozygous mutations and with no mutation in C0 concentration of the initial and the second screening (both CONCLUSIONS There are 5 new mutations which enriched the mutation spectrum of SLC22A5 gene. C0<5 μmol/L is highly correlated with SLC22A5 gene homozygous or compound heterozygous mutations. Children with truncated mutation may have lower C0 concentration than that with untruncated mutation in the initial screening.
Cardiomyopathies ; Carnitine/deficiency* ; Child ; Humans ; Hyperammonemia/genetics* ; Infant, Newborn ; Muscular Diseases/genetics* ; Mutation ; Solute Carrier Family 22 Member 5/genetics*

OBJECTIVE: To analyze the blood free carnitine (C0) level and SLC22A5 gene variants in 17 neonates with Primary carnitine deficiency (PCD) and to determine its incidence in local area and explore the correlation between C0 level and genotype. METHODS: 148 043 newborns born in 9 counties (cities and districts) of Ningde city from September 2016 to June 2021 were selected as study subjects. Blood free carnitine and acyl carnitine of 148 043 neonates were analyzed. Variants of the SLC22A5 gene were screened in those with blood C0 < 10 µmol/L, or C0 between 10 ∼ 15 µmol/L. Correlation between the free carnitine level and genetic variants was analyzed. RESULTS: In total 17 neonates were diagnosed with PCD, which yielded a prevalence of 1/8 707 in the region. Twelve variants of the SLC22A5 gene were identified, with the common ones including c.760C>T, c.1400C>G and c.51C>G. Compared with those carrying other variants of the gene, children carrying the c.760C>T variant had significantly lower C0 values (P < 0.01). CONCLUSION The prevalence of PCD is relatively high in Ningde area, and intervention measures should be taken to prevent and control the disease. The c. 760C>T variant is associated with lower level of C0, which can provide a clue for the diagnosis.
Humans ; Infant, Newborn ; Cardiomyopathies/diagnosis* ; Carnitine ; Hyperammonemia/diagnosis* ; Muscular Diseases/genetics* ; Solute Carrier Family 22 Member 5/genetics*

OBJECTIVE: To carry out mutation analysis and prenatal diagnosis for a family affected with primary carnitine deficiency. METHODS: Genomic DNA of the proband was extracted from peripheral blood sample 10 days after birth. The 10 exons and intron/exon boundaries of the SLC22A5 gene were subjected to PCR amplification and Sanger sequencing. The proband's mother was pregnant again two years after his birth. Fetal DNA was extracted from amniocytes and subjected to PCR and Sanger sequencing. RESULTS: Tandem mass spectrometric analysis of the proband revealed low level of plasma-free carnitine whilst organic acids in urine was normal. Compound heterozygous SLC22A5 mutations c.1195C>T (inherited from his father) and c.517delC (inherited from his mother) were detected in the proband. Prenatal diagnosis has detected no mutation in the fetus. The plasma-free carnitine was normal after birth. CONCLUSION Appropriate genetic testing and prenatal diagnosis can prevent further child with carnitine deficiency. The identification of c.517delC, a novel mutation, enriched the spectrum of SLC22A5 mutations.
Cardiomyopathies ; genetics ; Carnitine ; deficiency ; genetics ; Child, Preschool ; DNA Mutational Analysis ; Female ; Humans ; Hyperammonemia ; genetics ; Muscular Diseases ; genetics ; Mutation ; Pregnancy ; Prenatal Diagnosis ; Solute Carrier Family 22 Member 5 ; genetics

OBJECTIVE: To explore the genetic basis for a neonate featuring hyperammonemia. METHODS: The patient was examined and tested by tandem mass spectrometry and next generation sequencing (NGS). Suspected mutations were confirmed by Sanger sequencing of the proband and her parents. Potential impact of the mutation was predicted with SIFT, PolyPhen-2 and MutationTaste software. RESULTS: Plasma ammonia and alanine were significantly increased in the proband, while serum citrulline was decreased. The neonate was found to harbor compound heterozygous mutations of the CPS1 gene [c.1631C>T(p.T544M) and c.1981G>T(p.G661C)], which were respectively inherited from her father and mother. CONCLUSION The carbamoyl phosphate synthetase I deficiency of the proband can probably be attributed to the mutations of the CPS1 gene. Above finding has expanded the spectrum of CPS1 mutations in association with carbamoyl phosphate synthetase I deficiency.
Carbamoyl-Phosphate Synthase (Ammonia) ; genetics ; Carbamoyl-Phosphate Synthase I Deficiency Disease ; genetics ; Female ; High-Throughput Nucleotide Sequencing ; Humans ; Hyperammonemia ; diagnosis ; genetics ; Infant, Newborn ; Mutation

OBJECTIVETo investigate the incidences of urea cycle defects (UCDs) in the patients with hyperammonemia and study their etiology, clinical and laboratory features.

METHODSIn the past 7 years, 26 cases (10.2%) of UCDs were detected from 254 patients with hyperammonemia. The etiological diagnoses were made by blood amino acids analysis, urinary organic acid analysis and blood acylcarnitine profile analysis. Three patients with citrullinemia type II were further confirmed by liver pathological analysis and gene diagnosis.

RESULTSAmong 26 cases with UCDs, 15 had ornithine transcarbamylase (OTC) deficiency, 5 had citrullinemia type I, 3 had citrullinemia type II and 3 patients had arginemia. The age of onset of the patients ranged from 3 days to 13 years. Three cases (11.5%) developed hyperammonemic encephalopathy during neonatal period. Thirteen (50.0%), 7 (26.9%) and 3 (11.5%) cases developed clinical symptoms at the age of 1 to 12 months, 1 to 3 years and 6 to 13 years, respectively. Positive family history was found in 11 cases (42.3%). Among 26 patients with UCDs, 9 (34.6%) were hospitalized with the complains of seizures, psychomotor retardation, vomiting and unconsciousness, 8 (30.8%) with recurrent vomiting, headache and coma, 6 due to liver dysfunction. Intrahepatic cholestatic jaundice was found in 3 patients with citrullinemia type II. Blood ammonia ranged from 58 to 259 micromol/L on their first visit to our hospital. Twenty cases (76.9%) had liver dysfunction, 4 patients (15.4%) were diagnosed postmortem. Twenty-one patients got treatment and were followed up. Among them, 7 cases died of hyperammonemic encephalopathy or upper alimentary tract bleeding. Clinical improvement was observed in 14 cases. A boy with OTC deficiency who received a partial liver transplant from his mother showed normal general condition for two years.

CONCLUSIONSUCDs are the most frequent causes of congenital hyperammonemia. In this study, 26 patients (10.2%) with UCDs were identified from 254 patients with hyperammonemia resulting in encephalopathy and liver dysfunction. Early diagnosis and treatment can contribute a lot to improve the prognosis of the patients. Blood ammonia assay and further etiological analysis should be considered in the differential diagnosis of neurological and hepatic abnormality.

Adolescent ; Ammonia ; blood ; Child ; Child, Preschool ; Female ; Follow-Up Studies ; Humans ; Hyperammonemia ; congenital ; diagnosis ; genetics ; Infant ; Infant, Newborn ; Male ; Urea ; metabolism

OBJECTIVES: To investigate genotype-phenotype characteristics and long-term prognosis of neonatal carbamoyl phosphate synthetase 1 (CPS1) deficiency among children through newborn screening in Zhejiang province. METHODS: The clinical and follow-up data of children with CPS1 deficiency detected through neonatal screening and confirmed by tandem mass spectrometry and genetic testing in Zhejiang Province Newborn Disease Screening Center from September 2013 to August 2023 were retrospectively analyzed. RESULTS: A total of 4 056 755 newborns were screened and 6 cases of CPS1 deficiency were diagnosed through phenotypic and genetic testing. Ten different variations of CPS1 genewere identified in genetic testing, including 2 known pathogenic variations (c.2359C>T and c.1549+1G>T) and 8 unreported variations (c.3405-1G>T, c.2372C>T, c.1436C>T, c.2228T>C, c.2441G>A, c.3031G>A, c.3075T>C and c.390-403del). All patients had decreased citrulline levels (2.72-6.21 μmol/L), and varying degrees of elevated blood ammonia. The patients received restricted natural protein intake (special formula), arginine and supportive therapy after diagnosis, and were followed-up for a period ranging from 9 months to 10 years. Three patients experienced hyperammonemia, and one patient each had attention deficit hyperactivity disorder, transient facial twitching and increased muscle tone. One patient died, while the other five surviving patients had normal scores of the Ages & Stages Questionnaires (ASQ) and Griffiths Development Scales up to the present time; 4 cases had combined height or weight lag and one case was normal in height and weight. CONCLUSIONS Low citrulline levels and hyperammonemia are common in CPS1 deficiency patients in Zhejiang. Most gene variants identified were specific to individual families, and no hotspot mutations were found. Early diagnosis through newborn screening and following standardized treatment can significantly improve the prognosis of the patients.
Child ; Humans ; Infant, Newborn ; Carbamoyl-Phosphate Synthase I Deficiency Disease/therapy* ; Neonatal Screening ; Follow-Up Studies ; Hyperammonemia ; Citrulline/genetics* ; Retrospective Studies ; Mutation

OBJECTIVE: To analyze the metabolic profile and genetic variants for newborns with primary carnitine deficiency (PCD) from Guangxi, China. METHODS: From January 2014 to December 2019, 400 575 newborns from the jurisdiction of Guangxi Zhuang Autonomous Region Newborn Screening Center were subjected to tandem mass spectrometry (MS/MS) analysis. Newborns with positive results for PCD and their mothers were recalled for retesting. Those who were still positive were subjected to sequencing of the SLC22A5 gene. RESULTS: Twenty-two newborns and 9 mothers were diagnosed with PCD, which gave a prevalence rate of 1/18 208. Sequencing of 18 newborns and 4 mothers have identified 14 types of SLC22A5 gene variants, with the common ones including c.51C>G (10/44, 22.7%), c.1195C>T (9/44, 20.5%) and c.1400C>G (7/44, 15.9%), The c.517delC(p.L173Cfs*3) and c.1031C>T(p.T344I) were unreported previously and predicted to be pathogenic (PVS1+PM2_supporting+PM3+PP4) and likely pathogenic (PM1+PM2_supporting+PM3+PP3+PP4) based on the American College of Medical Genetics and Genomics standards and guidelines. CONCLUSION c.51C>G, c.1195C>T and c.1400C>G are the most common variants underlying PCD in Guangxi.
Cardiomyopathies ; Carnitine/deficiency* ; China ; Humans ; Hyperammonemia ; Infant, Newborn ; Metabolome ; Muscular Diseases ; Mutation ; Solute Carrier Family 22 Member 5/genetics* ; Tandem Mass Spectrometry

OBJECTIVETo study the gene mutation profile of primary carnitine deficiency (PCD) in neonates, and to provide a theoretical basis for early diagnosis and treatment, genetic counseling, and prenatal diagnosis of PCD.

METHODSAcylcarnitine profile analysis was performed by tandem mass spectrometry using 34 167 dry blood spots on filter paper. The SLC22A5 gene was sequenced and analyzed in neonates with free carnitine (C0) levels lower than 10 μmol/L as well as their parents.

RESULTSIn the acylcarnitine profile analysis, a C0 level lower than 10 μmol/L was found in 10 neonates, but C0 level was not reduced in their mothers. The 10 neonates had 10 types of mutations at 20 different sites in the SLC22A5 gene, which included 4 previously unreported mutations: c.976C>T, c.919delG, c.517delC, and c.338G>A. Bioinformatics analysis showed that the four new mutations were associated with a risk of high pathogenicity.

CONCLUSIONSTandem mass spectrometry combined with SLC22A5 gene sequencing may be useful for the early diagnosis of PCD. Identification of new mutations enriches the SLC22A5 gene mutation profile.

Cardiomyopathies ; diagnosis ; genetics ; Carnitine ; deficiency ; genetics ; Computational Biology ; Genetic Counseling ; Humans ; Hyperammonemia ; diagnosis ; genetics ; Infant, Newborn ; Muscular Diseases ; diagnosis ; genetics ; Mutation ; Solute Carrier Family 22 Member 5 ; genetics ; Tandem Mass Spectrometry

OBJECTIVETo identify potential mutation of SLC22A5 gene in a 5-month-old boy affected with primary carnitine deficiency and provide genetic counseling and prenatal diagnosis for the members of his family.

METHODSDNA was extracted from peripheral blood samples derived from the proband, his parents and elder sister, as well as amniotic fluid from his pregnant mother. All of the 10 exons of the SLC22A5 gene were amplified by PCR and subjected to Sanger sequencing. The amniotic fluid sample was also subjected to G-banded karyotyping and multiplex ligation-dependent probe amplification (MLPA).

RESULTSA homozygous mutation c.760C>T (p.R254X) of the SLC22A5 gene was detected in the proband. Heterozygous mutation c.760C>T (p.R254X) was also found in other family members including the fetus. The karyotyping and chromosomal microdeletion testing for the amniotic fluid sample were both normal.

CONCLUSIONThe newly identified homozygous nonsense c.760C>T (p.R254X) mutation of the SLC22A5 gene probably underlies the primary carnitine deficiency of the proband. Genetic counseling and prenatal diagnosis have been provided for this family.

Adult ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Cardiomyopathies ; embryology ; genetics ; Carnitine ; deficiency ; genetics ; China ; Exons ; Female ; Genotype ; Humans ; Hyperammonemia ; embryology ; genetics ; Infant ; Male ; Molecular Sequence Data ; Muscular Diseases ; embryology ; genetics ; Organic Cation Transport Proteins ; genetics ; Pedigree ; Pregnancy ; Prenatal Diagnosis ; Solute Carrier Family 22 Member 5