Treatment and management for children with urea cycle disorder in chronic stage / 浙江大学学报·医学版

Urea cycle disorder (UCD) is a group of inherited metabolic diseases with high disability or fatality rate, which need long-term drug treatment and diet management. Except those with Citrin deficiency or liver transplantation, all pediatric patients require lifelong low protein diet with safe levels of protein intake and adequate energy and lipids supply for their corresponding age; supplementing essential amino acids and protein-free milk are also needed if necessary. The drugs for long-term use include nitrogen scavengers (sodium benzoate, sodium phenylbutyrate, glycerol phenylbutyrate), urea cycle activation/substrate supplementation agents (N-carbamylglutamate, arginine, citrulline), etc. Liver transplantation is recommended for pediatric patients not responding to standard diet and drug treatment, and those with severe progressive liver disease and/or recurrent metabolic decompensations. Gene therapy, stem cell therapy, enzyme therapy and other novel technologies may offer options for treatment in UCD patients. The regular biochemical assessments like blood ammonia, liver function and plasma amino acid profile are needed, and physical growth, intellectual development, nutritional intake should be also evaluated for adjusting treatment in time.

Clinical and ASS1 gene variant analysis of three Chinese pedigrees affected with Citrullinemia type I / 中华医学遗传学杂志

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.

Analysis of SLC25A13 gene variants in 16 infants with intrahepatic cholestasis caused by citrin protein deficiency / 中华医学遗传学杂志

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.

Physical and neuropsychological development of children with Citrin deficiency / 中国当代儿科杂志

OBJECTIVES@#To study the physical and neuropsychological development of children with Citrin deficiency (CD).@*METHODS@#A total of 93 children, aged 1.9-59.8 months, who were diagnosed with CD by @*RESULTS@#For the 93 children with CD, the incidence rate of failure to thrive was 25% (23 children) and the proportion of small for gestational age was 47% (44 children). For the 100 cases of CD, the incidence rates of growth retardation, underweight, emaciation, overweight, and microcephalus were 23% (23 cases), 14% (14 cases), 4% (4 cases), 8% (8 cases), and 9% (9 cases), respectively. The incidence rate of neuropsychological developmental delay was 25% (25 cases), and the incidence rates of development delay in the five domains of adaptability, gross motor, fine motor, language, and social ability were 7% (7 cases), 15% (15 cases), 7% (7 cases), 9% (9 cases), and 7% (7 cases), respectively.@*CONCLUSIONS@#Physical and neuropsychological developmental delay can be observed in children with CD, and physical and neuropsychological development should be regularly assessed.

Clinical characteristics and gene variants of patients with infantile intrahepatic cholestasis / 中国当代儿科杂志

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.

Clinical and biochemical profiles of Filipino patients with distal urea cycle disorders detected by abnormal expanded newborn screening

Objective@#The study is a retrospective review which provides preliminary data on the correlation between biochemical profiles and initial clinical manifestation of patients diagnosed to have argininosuccinate synthetase deficiency (ASSD) and argininosuccinate lyase deficiency (ASLD) detected by expanded newborn screening (ENBS). @*Methods@#This is a study of five distal UCD patients initially detected by elevated citrulline on ENBS. Medical charts of the patients were reviewed. The initial clinical manifestations of the patients were correlated with results of biochemical tests. @*Results@#There were four cases of ASLD and one case of ASSD reviewed in this study. All cases of ASLD were confirmed by the presence of argininosuccinic acid (ASA) in the urine metabolic screen (UMS). The plasma citrulline level of the ASSD patient is significantly elevated as compared to the ASLD patients (2,690 µmol/L; NV: 10-45 µmol/L). The ASSD patient and one ASLD patient were symptomatic within the first six days of life. Both presented with significantly elevated plasma ammonia, citrulline and glutamine levels. Three ASLD patients were asymptomatic on initial screening. @*Conclusion@#ENBS has shown importance in the early detection and management of ASSD and ASLD. Early initiation of management may prevent hyperammonemic crises. Long term outcome studies are needed to look into the correlation of neurodevelopmental outcome with lifelong accumulation of citrulline and glutamine in ASSD and ASA in ASLD.

Carrier frequency of autosomal recessive disorders (BC, BLAD, FXID and CVM) in Holstein cows in Jalisco, Mexico

The hereditary autosomal recessive disorders bovine citrullinemia (BC), bovine leukocyte adhesion deficiency (BLAD), factor XI deficiency (FXID), and complex vertebral malformation (CVM) have affected dairy cattle breeding significantly around the world. This study examined the carrier frequency of BC, BLAD, FXID, and CVM autosomal recessive disorders in Bos taurus Holstein cows bred in the Altos Norte region of the state of Jalisco, Mexico. We extracted DNA from 408 random samples of peripheral blood, and then used polymerase chain reaction (PCR) to identify insertion mutations for FXID, and PCR with restriction fragment length polymorphism (PCR-RFLP) for CVM, BC and BLAD. We visualized the PCR products using agarose gel electrophoresis stained with GelRed®. We found that 100% of wild-type (N/N) allele homozygous animals for genes CD18, ASS, and FXI were free of the mutations for BLAD, BC and FXID respectively. For gene SLC35A3 we estimated total carrier frequency of 10.3% and allele frequency of 5%.(AU)

A novel SLC25A13 variant and the resultant aberrant transcript identified in a pedigree affected with citrin deficiency / 中华医学遗传学杂志

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.

Citrulinemia tipo I con insuficiencia hepática recurrente en un niño / Citrullinemia type I with recurrent liver failure in a child

La citrulinemia tipo I es un desorden autosómico recesivo causado por la mutación del gen ASS1, que expresa argininosuccinato sintetasa, enzima limitante del ciclo de la urea. Las variantes clásicas están asociadas con la forma neonatal/infantil, que llevan a hiperamoniemia y a la muerte si el tratamiento no es instaurado. Los síntomas iniciales de los trastornos del ciclo de la urea incluyen deterioro neurológico con leve o moderado daño hepático. Reportamos un caso de falla hepática recurrente en un lactante con diagnóstico de citrulinemia tipo I sin compromiso neurológico grave, que fue derivado a nuestro centro para trasplante hepático. La falla hepática aguda puede ser causada por una gran variedad de desórdenes, dentro de los que se incluyen errores congénitos del metabolismo. El tratamiento adecuado de los trastornos del ciclo de la urea y, en particular, la citrulinemia I puede evitar la necesidad de un trasplante.

Citrullinemia type I is an autosomal recessive disorder caused by mutation of the gene expressing ASS1 argininosuccinate synthetase, limiting enzyme of the urea cycle. The classic variants are associated with neonatal/infantile forms that cause hyperammonemia leading to death if treatment is not established. Initial symptoms of disorders of the urea cycle include neurological impairment with mild or moderate liver damage. We report a case of recurrent liver failure in an infant diagnosed with type I citrullinemia without severe neurological involvement that was referred to our center for liver transplantation. Acute liver failure can be caused by a wide range of disorders in which inborn errors ofmetabolism are included. Appropriate treatment of disorders of the urea cycle and in particular citrullinemia I can avoid the need for a transplant.

Mutational analysis of ASS1, ASL and SLC25A13 genes in six Chinese patients with citrullinemia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect potential mutations in six patients with citrullinemia.</p><p><b>METHODS</b>Genomic 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.</p><p><b>RESULTS</b>One 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.</p><p><b>CONCLUSION</b>This study has confirmed the molecular diagnosis of citrullinemia in six patients and expanded the mutational spectrum underlying citrullinemia.</p>

Analysis of clinical features and SLC25A13 gene mutations in a family affected with neonatal intrahepatic cholestasis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the clinical features and potential mutations of the SLC25A13 gene in a boy affected with neonatal intrahepatic cholestasis.</p><p><b>METHODS</b>Clinical data and peripheral venous blood sample of the child, and peripheral venous blood samples of both parents, were collected. All coding exons of the SLC25A13 gene were amplified with PCR and subjected to direct DNA sequencing.</p><p><b>RESULTS</b>The boy was found to be a compound heterozygote carrying c.851_854delGTAT and IVS16ins3kb mutations of the SLC25A13 gene, which were respectively inherited from his mother and father.</p><p><b>CONCLUSION</b>Based on its clinical and genetic features, the patient was diagnosed with neonatal intrahepatic cholestasis caused by citrin deficiency.</p>

Citrulinemia de presentación atípica: hipo persistente: a propósito de un caso / Citrullinemia with an atypical presentation: persistent hiccups: case report

Se informa el caso de un neonato que desarrolló encefalopatía en el transcurso de los primeros tres días de vida. Presentaba hipo persistente, que evolucionó a coma profundo 72 horas después de la admisión al hospital. Los parámetros de septicemia y el análisis del líquido cefalorraquídeo (LCR) fueron normales. Tras la evaluación metabòlica, se confirmó la presencia de hiperamoniemia e hipercitrulinemia. El índice de la concentración de LCR/glicina en plasma era normal. Esto no coincidió con nuestro diagnóstico inicial de hiperglicinemia no cetósica, que suele manifestarse con hipo. Se recomienda tener en cuenta la deficiencia de ácido argininosuccínico sintetasa (ASD por su sigla en inglés; citrulinemia) de inicio neonatal en el diagnóstico diferencial de encefalopatía asociada con hipo durante el período neonatal, lo que sugiere una enzimopatía congénita.

We report an infant who developed encephalopathy within the first 3 days of life. He had persistent hiccups that progressed to deep coma 72 hours after admission. The sepsis parameters and cerebrospinal fluid examination (CSF) were normal. The metabolic evaluation confirmed hyperammonemia, and hypercitrullinemia. The ratio of CSF/plasma glycine concentration was normal. This did not agree with our initial diagnosis of nonketotic hyperglycinemia where hiccups is present more often. Neonatal onset of argininosuccinic acid synthetase deficiency (ASD; citrullinemia) should be brought in mind in the differential diagnosis of encephalopathy in association with hiccups in the neonatal period suggesting inborn errors of metabolism.

The first successful live birth following preimplantation genetic diagnosis using PCR for type 1 citrullinemia

Type 1 citrullinemia (CTLN1) is an autosomal recessive inherited metabolic disorder caused by anargininosuccinicnate synthetase deficiency. The patient was a 38-year-old Korean woman who is a carrier for CTLN1 and her first baby was diagnosed with CTLN1. Preimplantation genetic diagnosis (PGD) for CTLN1 in day 3 embryos using polymerase chain reaction was performed for live birth of healthy baby who is no affected with CTLN1. One unaffected blastocyst was transferred. This resulted in a clinical pregnancy and the live birth of healthy male twin. They were confirmed to be unaffected with CTNL1 by post natal diagnosis. This is the first case report of the use of PGD for CTNL1.

Genetic analysis of ASS1, ASL and SLC25A13 in citrullinemia patients / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect potential mutations of Y9ASS1, ASL and SLC25A13 genes in four patients manifesting citrullinemia.</p><p><b>METHODS</b>Genomic 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.</p><p><b>RESULTS</b>Based 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.</p><p><b>CONCLUSION</b>Through analysis of relevant pathogenic genes, four patients have been diagnosed.</p>

ASS1 gene mutation in a neonate with citrullinemia type I / 中华儿科杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHOD</b>Genomic 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.</p><p><b>RESULT</b>Double 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.</p><p><b>CONCLUSION</b>Double 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.</p>

Characteristics of the plasma amino acid spectrum of neonatal intrahepatic cholestasis caused by citrin deficiency / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the plasma amino acid spectrum in infants more than 1-year-old with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) in order to identify potential diagnostic markers of NICCD.</p><p><b>METHODS</b>Infants less than 1 year of age who had been referred to our hospital for investigation of suspected conjugated hyperbilirubinemia between June 2003 and June 2009 were eligible for enrollment. A total of 182 infants were enrolled and divided into three groups: infants diagnosed with NICCD (n = 24), according to gene testing and/or western blotting results; infants diagnosed with biliary atresia (BA; n = 20), according to intra-operative cholangiography findings; and infants diagnosed with idiopathic neonatal intrahepatic hepatitis (INH; n = 138), according to exclusionary findings for diseases affecting the extrahepatic biliary system and no positive serology results to indicate infections with hepatitis B, C, A or E, toxoplasmosis, rubella, herpes simplex, human immunodeficiency virus-1, or syphilis. The plasma amino acid spectrum of each infant was analyzed by tandem mass spectrometry (MS/MS). The concentrations of 18 amino acids, as well as the ratio of each amino acid to total amino acids, were compared among the three groups. Selected ratios of amino acids were analyzed by receiver operating characteristic (ROC) curve analysis.</p><p><b>RESULTS</b>Compared with the BA and INH groups, the NICCD group had significantly lower levels of alanine (Ala; 175.7 and 205.7 vs. 136.3 mumol/L, P = 0.0001), aspartic acid (Asp; 47.5 and 43.1 vs. 31.55 mumol/L, P = 0.0041), glutamic acid (Glu; 276.16 and 263.24 vs. 175.71 mumol/L, P = 0.0075) and tryptophan (Trp; 41.90 and 47.97 vs. 28.51 mumol/L, P = 0.0003), but significantly higher levels of methionine (Met; 28.24 and 29.35 vs. 71.40 mumol/L, P = 0.0390), tyrosine (Tyr; 55.8 and 57.02 vs. 116.81 mumol/L, P = 0.0072) and citrulline (Cit; 15.09 and 15.65 vs. 97.42 mumol/L, P = 0.0001). The ratio of each amino acid to total amino acids showed the same trends for the NICCD group. The calculated areas under the ROC curves of the ratios of Cit, Tyr, and Met to the total amino acids were 0.874 (95% CI: 0.752 - 0.996), 0.814 (95% CI: 0.706 - 0.923), and 0.705 (95% CI: 0.535 - 0.875) respectively. The calculated area under the ROC curve of the ratio of Cit to Ala was 0.893 (95% CI: 0.781 - 1.005), and when the cut-off value of the ratio of Cit to Ala was 0.14 for diagnosis of NICCD, the sensitivity and specificity were 75% and 95% respectively.</p><p><b>CONCLUSION</b>The plasma amino acid spectrum may represent a diagnostic indicator for NICCD, particularly the ratio of Cit to Ala.</p>

Utilization of high-resolution melting analysis to screen patients with neonatal intrahepatic cholestasis caused by citrin deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the feasibility of high-resolution melting (HRM) analysis for screening patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD).</p><p><b>METHODS</b>Based 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.</p><p><b>RESULTS</b>HRM 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.</p><p><b>CONCLUSION</b>HRM analysis is a convenient, high-throughput and rapid technique for the screening of NICCD patients.</p>

Auxiliary partial orthotopic liver transplantation for adult onset type II citrullinemia / 대한외과학회지

Adult-onset type II citrullinemia (CTLN2) is a disorder caused by an inborn error of metabolism affecting the liver. CTLN2 is an autosomal recessive disorder characterized by recurrent encephalopathy with hyperammonemia due to highly elevated plasma levels of citrulline and ammonia, caused by a deficiency of argininosuccinate synthetase in the liver. A small number of patients have undergone liver transplantation with favorable results. In Korea, the limitations of the deceased donor pool have made living donor liver transplantation a common alternative treatment option. We report the case of a patient with type II citrullinemia who was treated successfully with auxiliary partial orthotopic liver transplantation (APOLT) from a living donor. This is the first description of an APOLT for a patient with adult onset type II citrullinemia in Korea.

Novel Compound Heterozygote Mutations of the SLC25A13 Gene in an Infant with Neonatal-onset Type II Citrullinemia Detected by Newborn Mass Screening

Citrin deficiency caused by the SLC25A13 gene mutations is associated with both neonatal-onset type II citrullinemia (CTLN2), also known as neonatal intrahepatic cholestasis caused by citrin deficiency and adult-onset CTLN2. Neonatal-onset CTLN2 is an autosomal recessive disorder characterized by poor growth, intrahepatic cholestasis, and increased serum citrulline. A 16-days old infant with hyperammonemia was referred for evaluation of increased plasma citrulline diagnosed using tandem mass spectrometry. Blood amino acid analysis showed significant elevation of citrulline. Mild elevation in serum galactose levels had been found. DNA analysis of the SLC25A13 gene in this patient showed two novel compound heterozygous mutations, c.221C>T in exon4 and c.1645C in exon16 (p.[Ser74Phe]+[Gln549X]). We suggest that infants with a high serum citrulline level on a tandem mass screening test are candidates for gene analysis and blood amino acid analysis for neonatal-onset CTLN2.

ASS1 mutation leading to citrullinemia I in a Chinese Han family / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate potential mutation of the ASS1 gene in a male infant with acute citrullinemia type I.</p><p><b>METHODS</b>Genomic DNA was prepared from peripheral blood samples of the family members. Mutation analysis of the 14 ASS1 exons was carried out by PCR and direct DNA sequencing.</p><p><b>RESULTS</b>A homozygous missense mutation of c.970G>A located in exon 13, which results in p.G324S, was identified in the child. Sequencing of the parents showed a heterozygous status for the same mutation.</p><p><b>CONCLUSION</b>A missense mutation of c.970G>A in the ASS1 gene is responsible for the pathogenesis of the disease in the infant.</p>