OBJECTIVE: To analyze the clinical manifestation and genetic mutation of a child with tyrosinemia type I but without elevated succinylacetone. METHODS: Clinical data of the patient was collected. Tandem mass spectrometry and gas chromatography mass spectrometry were used to analyze the blood amino acid and urine organic acid component of the proband. DNA was extracted from the child and his parents and used for mutation analysis. RESULTS: The proband was of acute type, with features including hepatomegaly, jaundice, anemia and tendency of bleeding. Serum levels of Tyrosine, Methionine and Phenylalanine were 397.12 μmol/L, 896.16 μmol/L and 292.52 μmol/L, respectively, which all distinctly exceeded the normal levels. The level of phenyllactic acid and 4-hydroxyphenyl-lactic acid of proband's urine were 17.4 μmol/L and 417.0 μmol/L, respectively, which also exceeded the normal levels, but the level of succinylacetone was within the normal range. Compound heterozygous mutations of the FAH gene, namely c.634delT (p.L212Wfs*20) and c.455G>A (p.W152X), were detected in the proband, which were both predicted to be pathogenic and were inherited from her father and mother, respectively. CONCLUSION For children with tyrosinemia type I, detection of urine succinylacetone by gas phase mass spectrometry can be negative. The diagnosis of tyrosinemia type I must rely on genetic testing and/or enzymatic assaying.
DNA Mutational Analysis ; Female ; Genetic Testing ; Heptanoates ; Humans ; Male ; Tyrosinemias

Humans ; Infant ; Infant, Low Birth Weight ; Infant, Newborn ; Male ; Tyrosinemias ; diagnosis ; therapy

OBJECTIVE: To analyze the clinical phenotype and genetic basis for a child with acute form of tyrosinemia type I (TYRSN1). METHODS: A child with TYRSN1 who presented at the Gansu Provincial Maternal and Child Health Care Hospital in October 2020 was selected as the subject. The child was subjected to tandem mass spectrometry (MS-MS) and urine gas chromatography-mass spectrometry (GC-MS) for the detection of inherited metabolic disorders, in addition with whole exome sequencing (WES). Candidate variants were validated by Sanger sequencing. RESULTS: The child's clinical features included abdominal distension, hepatomegaly, anemia and tendency of bleeding. By mass spectrometry analysis, her serum and urine tyrosine and succinylacetone levels have both exceeded the normal ranges. WES and Sanger sequencing revealed that she has harbored c.1062+5G>A and c.943T>C (p.Cys315Arg) compound heterozygous variants of the FAH gene, which were inherited from her father and mother, respectively. Among these, the c.943T>C was unreported previously. CONCLUSION Considering her clinical phenotype and result of genetic testing, the child was diagnosed with TYRSN1 (acute type). The compound heterozygous variants of the FAH gene probably underlay the disease in this child. Above finding has further expanded the spectrum of FAH gene variants, and provided a basis for accurate treatment, genetic counseling and prenatal diagnosis for her family.
Female ; Humans ; Gas Chromatography-Mass Spectrometry ; Genetic Testing ; Mutation ; Phenotype ; Prenatal Diagnosis ; Tyrosinemias/genetics* ; Child

Child, Preschool ; Female ; Humans ; Infant ; Male ; Methionine ; blood ; Tyrosine ; blood ; Tyrosine Transaminase ; deficiency ; Tyrosinemias ; blood ; diagnosis ; enzymology ; pathology ; therapy

Tyrosinemia type 1 is an autosomal recessive inborn error of tyrosine metabolism that caused a mutation in the gene coding for the enzyme fumarylacetoacetate hydrolase(FAH). As a result, maleylacetoacetate(MAA) and fumarylacetoacetate(FAA) are formed. The accumulated FAA is converted into succinylacetone(SA) and succinylacetoacetate(SAA) which are excreted in urine. The first report with typical clinical and biochemical findings was presented by Sakai in 1957. Clinically, the disorder is characterized by progressive liver damage with liver failure, a high risk of hepatocellular carcinoma and renal tubular dysfunction hypophosphataemic rickets. Some patients have porphyria-like episodes. Liver transplantation has been the ultimate treatment of tyrosinemia. However pharmacological therapy with 2-(2-nitro-4-trifluoromethylbenzoyl) -1,3-cyclohexanedione(NTBC) has offered a new therapeutic option in addition to dietary restriction of tyrosine and phenylalanine. We experienced a case of tyrosinemia type 1 with cytomegalovirus infection in a 4-month-old male who improved by dietary restriction of tyrosine and phenylalanine.
Carcinoma, Hepatocellular ; Clinical Coding ; Cytomegalovirus Infections* ; Cytomegalovirus* ; Humans ; Infant ; Liver ; Liver Failure ; Liver Transplantation ; Male ; Metabolism ; Phenylalanine ; Rickets ; Tyrosine ; Tyrosinemias*

OBJECTIVETo analyze clinical data and gene mutations in 3 Chinese patients with tyrosinemia type I, and to explore the correlation between genotypes and phenotypes.

METHODSThree patients suspected with tyrosinemia I were tested by tandem mass spectrometry for the level of tyrosine, phenylalanine and succinylacetone in the blood, and by gas chromatography-mass spectrometry to determine the level of succinylacetone and organic acid in their urine. With the diagnosis established, the FAH gene was analyzed with polymerase chain reaction (PCR) and direct sequencing.

RESULTSTwo patients had acute onset of the disease, while another had subacute onset of the disease, with features including hepatomegaly and remarkably increased tyrosine and succinylacetone in the blood. Five mutations were detected in the FAH gene, which included c.455G>A (W152X), c.520C>T (R174X), c.974_976delCGAinsGC, c.1027 G>A (G343R) and c.1100 G>A (W367X), among which c.455G>A (W152X), c.974_976delCGAinsGC and c.1100 G>A (W367X) were not reported previously.

CONCLUSIONTyrosinemia type I may be effectively diagnosed with the level of tyrosine and succinylacetone by tandem mass spectrometry and succinylacetone in the urine by gas chromatography mass spectrometry. Detection of underlying mutations mutations will be helpful for genetic counseling and further research.

Asian Continental Ancestry Group ; genetics ; Base Sequence ; China ; Female ; Humans ; Hydrolases ; genetics ; Infant ; Male ; Mutation ; Tyrosinemias ; diagnosis ; genetics

Tyrosinemia type I is an autosomal recessive disorder of amino acid metabolism and is caused by a deficiency of fumarylacetoacetate hydrolase(FAH), the last enzyme in the catabolic pathway of tyrosine. The disease is characterized by hepatic dysfunction, hepatocellular carcinomas, renal tubular dysfunction, rickets, and neurologic crises. We experienced 2 cases(a 4-day-old girl, a 7- month-old girl) of acute form of tyrosinemia type I. Case 1 was presented with tachypnea, vomiting and prolonged PT and aPTT. Case 2 was presented with systemic jaundice, irritability, an odor resembling boiled cabbage, and hepatic dysfunction. The diagnosis was made by demonstrating elevated plasma levels of tyrsione and other amino acids, and urinary excretion of succinylacetone. Both of the patients had a significant coagulopathy which was not treated by transfusion of fresh frozen plasma and cryoprecipitate. We report two tyrosinemic infants who were presented with severe coagulopathy.
Amino Acids ; Brassica ; Carcinoma, Hepatocellular ; Diagnosis ; Female ; Humans ; Infant ; Jaundice ; Metabolism ; Odors ; Plasma ; Rickets ; Tachypnea ; Tyrosine ; Tyrosinemias* ; Vomiting

Any infant noted to be jaundiced at 2 weeks of age should be evaluated for cholestasis with measurement of total and direct serum bilirubin. With the insight into the clinical phenotype and the genotype-phenotype correlations, it is now possible to evaluate more precisely the neonate who presents with conjugated hyperbilirubinemia. Testing should be performed for the specific treatable causes of neonatal cholestasis, specifically sepsis, galactosemia, tyrosinemia, citrin deficiency and endocrine disorders. Biliary atresia must be excluded. Low levels of serum gamma-glutamyl transferase in the presence of cholestasis should suggest progressive familial intrahepatic cholestasis type 1, 2, or arthrogryposis- renal dysfunction-cholestasis syndrome. If the serum bile acid level is low, a bile acid synthetic defect should be considered. Molecular genetic testing and molecular-based diagnostic strategies are in evolution.
Bile ; Biliary Atresia ; Bilirubin ; Cholestasis* ; Cholestasis, Intrahepatic ; Galactosemias ; Genetic Association Studies ; Humans ; Hyperbilirubinemia ; Infant ; Infant, Newborn ; Molecular Biology ; Phenotype ; Sepsis ; Transferases ; Tyrosinemias

BACKGROUNDMutations in fumarylacetoacetate hydrolase (FAH) gene can lead to tyrosinemia type 1 (HT1), a relatively rare autosomal recessive disorder. To date, no molecular genetic defects of HT1 in China have been described. We investigated a Chinese family with a HT1 child to identify mutations in FAH.

METHODSDNA sequencing was used for mutations screening in FAH gene. Real-time polymerase chain reaction (PCR) was performed to determine the FAH gene expression level. To confirm the presence of degradation by the nonsense-mediated mRNA decay pathway (NMD), the fragments containing R237X mutations were analyzed by primer introduced restriction analysis-polymerase chain reaction (PIRA-PCR) and cDNA sequencing. Finally, the effects of the mutations reported in this study were predicted by online softwares.

RESULTSA boy aged 3 years and 8 months was diagnosed clinically with HT1 based on his manifestations and biochemical abnormalities. Screening of FAH gene revealed two heterozygous mutations R237X and L375P transmitted from his mother and father respectively. In this pedigree, the amount of FAH mRNA relative to a healthy control was 0.44 for the patient, 0.77 for his mother and 1.07 for his father. Moreover, both PIRA-PCR and cDNA sequencing showed significant reduction of the FAH mRNA with R237X nonsense mutation. The missense mutation of L375P was not reported previously and prediction software showed that this mutation decreased the stability of protein structure and affected protein function.

CONCLUSIONSThis is the first case of HT1 analyzed by molecular genetics in China. The R237X mutation in FAH down- regulates the FAH gene expression, and the L375P mutation perhaps interrupts the secondary structure of FAH protein.

Child, Preschool ; China ; Humans ; Hydrolases ; genetics ; Male ; Molecular Sequence Data ; Mutation ; Mutation, Missense ; genetics ; Nonsense Mediated mRNA Decay ; genetics ; Real-Time Polymerase Chain Reaction ; Tyrosinemias ; genetics

OBJECTIVETo establish the diagnostic method of tyrosinemia type 1 and evaluate its value, the succinylacetone levels in the blood of suspected patients with tyrosinemia were tested by tandem mass spectrometry, and the succinylacetone in the urine was tested by gas chromatography-mass spectrometry.

METHODA total of 190 patients suspected of having tyrosinemia, were tested by tandem mass spectrometry for measurement of the level of succinylacetone in the blood, and detected by gas chromatography-mass spectrometry for measurement of the level of succinylacetone and organic acid in the urine. The method of measuring the level of succinylacetone in blood by tandem mass spectrometry as follows: After the diameter of 3 mm dry blood spots were punched into wells of 96-well plate, 100 µl 80% acetonitrile were added into each well, which contained hydrazine monohydrate and the internal standard of succinylacetone. The supernatant fluid were transferred to another 96-well plate and dried under heated nitrogen, after the plate was incubated for 30 min at 65°C. The residual hydrazine reagent was removed by addition of 100 µl methanol to each well and evaporated under heated nitrogen. The mobile phase (80% acetonitrile) was added to each well and 20 µl samples were tested by tandem mass spectrometry. The diagnostic terms were the clinical manifestation and the high level of succinylacetone in both blood and urine.

RESULTEleven patients were diagnosed as tyrosinemia type 1, with 9 males and 2 females. Their ages ranged from 2 months to 6 years. The succinylacetone levels in the blood of the patients were remarkably increased (7.26-31.09 µmol/L), with an average of (14.2 ± 7.8)µmol/L. Seven patients were tested for the level of succinylacetone in the urine by gas chromatography-mass spectrometry, and 4 were positive and 3 negative. Their tyrosine levels in the blood were 190-543 µmol/L(Normal: 20 - 100 µmol/L), with an average of (327.3 ± 125.8) µmol/L. All the patients presented the symptoms of hepatomegaly. Among them, 9 patients died and 2 patients were improved after treatment.

CONCLUSIONThe higher levels of succinylacetone in the blood or urine is a remarkable evidence for the diagnosis of tyrosinemia type 1. Determination of succinylacetone in the dry blood spots using tandem mass spectrometry was a good method for diagnosis of tyrosinemia type 1. To test succinylacetone in urine by gas chromatography-mass spectrometry may yield a false-negative result for tyrosinemia type 1.

Adolescent ; Child ; Child, Preschool ; Female ; Gas Chromatography-Mass Spectrometry ; Heptanoates ; blood ; urine ; Humans ; Infant ; Infant, Newborn ; Male ; Tandem Mass Spectrometry ; Tyrosinemias ; blood ; diagnosis ; urine