Amino Acid Metabolism, Inborn Errors ; blood ; diagnosis ; Female ; Humans ; Infant ; Methylmalonic Acid ; blood

Amino Acid Metabolism, Inborn Errors ; blood ; diagnosis ; Humans ; Infant, Newborn ; Male

Acetyl-CoA C-Acyltransferase ; deficiency ; Amino Acid Metabolism, Inborn Errors ; diagnosis ; enzymology ; metabolism ; Diagnosis, Differential ; Humans ; Infant ; Isoleucine ; metabolism ; Male

OBJECTIVEMany inborn errors of metabolism have similar presenting clinical manifestations, making early diagnosis difficult. We report our experience with tandem mass spectrometry combined with urine gas chromatography/mass spectrometry as a means of definitively diagnosing inborn errors of metabolism.

METHODSOne hundred and thirty-two children with suspected inborn errors of metabolism but without specific clinical manifestations, admitted to the Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine between June 1, 2003 and September 30, 2006, were studied. Children received routine biochemical examinations, as well as mass spectrometry and gas chromatography-mass spectrometry.

RESULTSFifteen cases (11.5%) were confirmed as having inborn errors of metabolism, including 6 cases of methylmalonic acidemia, 2 of propionic academia, 2 of Type II citrullinemia, 1 of biotinidase deficiency, 1 of tyrosinemia, 1 of maple syrup urine disease, 1 of omithine transcarbamylase deficiency and 1 of very long chain Acyl CoA dehydrogenase deficiency.

CONCLUSIONSThe combined use of tandem mass spectrometry with urine gas chromatography mass spectrometry is useful for early diagnosis of inborn errors of metabolism in children with suspected inborn errors of metabolism but without specific clinical manifestations.

Amino Acid Metabolism, Inborn Errors ; diagnosis ; Child ; Child, Preschool ; Female ; Gas Chromatography-Mass Spectrometry ; methods ; Humans ; Infant ; Infant, Newborn ; Lipid Metabolism, Inborn Errors ; diagnosis ; Male ; Metabolism, Inborn Errors ; diagnosis ; urine ; Tandem Mass Spectrometry ; methods

Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare autosomal recessive disorder. This paper reports three cases of SSADH deficiency in infants. The infants developed the symptoms including developmental delay, intellectual disability, hypotonia, hyporeflexia and seizures. The electroencephalogram (EEG) showed background slowing and focal spike discharges in all of 3 patients. Head magnetic resonance imaging (MRI) demonstrated abnormalities in 2 patients, including basal ganglia damage and increased T2-weighted signal in bilateral cerebral peduncles. Urinary organic acid analysis with gas chromatography-mass spectrometry (GC-MS) revealed increased levels of 4-hydroxybutyrate (GHB) in 3 patients. SSADH deficiency was definitely diagnosed based on the clinical manifestations and the results of urinary organic acid analysis in the 3 children. It was concluded that early urine organic acid analysis is essential for children presenting with mental retardation, neuropsychiatric disturbance or epilepsy of unknown etiology.
Amino Acid Metabolism, Inborn Errors ; diagnosis ; therapy ; Developmental Disabilities ; Diagnosis, Differential ; Female ; Humans ; Infant ; Succinate-Semialdehyde Dehydrogenase ; deficiency

OBJECTIVETo study gene mutations in four pedigrees with methymalonic aciduria, as well as the feasibility of prenatal diagnosis of methymalonic aciduria.

METHODSHigh-throughput sequencing was performed for related genes in the peripheral blood of children or parents who were diagnosed with methymalonic aciduria to identify the loci with mutations. Then amplification primers were designed for each locus, and PCR and direct sequencing were performed to validate the sequencing in the first generation in the four pedigrees. Whether the mutations were pathogenic were determined with reference to literature review and medical history. In the pedigrees 1, 3, and 4, ultrasound-guided chorionic villi biopsy was performed at weeks 11-13 of pregnancy to perform early prenatal diagnosis.

RESULTSIn pedigree 1, c.656A>T and c.729-730insTT heterozygous mutations in the MUT gene were detected in the proband's father and mother, respectively. Early prenatal diagnosis showed c.656A>T and c.729-730insTT double heterozygous mutations in the fetus. The couple decided to terminate pregnancy. In pedigree 2, c.1106G>A and c.755-756insA double heterozygous mutations in the MUT gene were detected in the proband. c.1106G>A came from the father and c.755-756insA came from the mother. In pedigree 3, c.217C>T and c.609G>A double heterozygous mutations in the MMACHC gene were detected in the proband. c.217C>T came from the father and c.609G>A came from the mother. Prenatal diagnosis showed c.609G>A heterozygous mutation in the fetus. The baby was successfully delivered, and the result of umbilical cord blood testing was consistent with the prenatal diagnosis. In pedigree 4, c.609G>A and c.567dupT double heterozygous mutations in the MMACHC gene were detected in the proband. c.609G>A came from the father and c.567dupT came from the mother. Prenatal diagnosis showed c.567dupT heterozygous mutation in the fetus. The baby was successfully delivered, and the result of umbilical cord blood testing was consistent with the prenatal diagnosis.

CONCLUSIONSIdentification of gene mutations helps with prenatal diagnosis in pedigrees with methymalonic aciduria.

Amino Acid Metabolism, Inborn Errors ; diagnosis ; genetics ; DNA Mutational Analysis ; Female ; Humans ; Male ; Mutation ; Pedigree ; Prenatal Diagnosis

A 9-day-old male patient was admitted to the hospital because of cough, anhelation, feeding difficulty and lethargy. The diagnostic examinations indicated pulmonary infection, severe metabolic acidosis, hyperglycemia, hyperammonemia and pancytopenia in the patient. Blood and urine screening and isovaleryl-CoA dehydrogenase (IVD) gene detection for inherited metabolic diseases were performed to clarify the etiology. Tandem mass spectrometric screening for blood showed an elevated isovalerylcarnitine (C5) level. The organic acid analysis of urine by gas chromatography-mass spectrometry showed significantly increased levels in isovaleryl glycine and 3-hydroxyisovaleric acid. Homozygous mutations (c.1208A>G, p.Tyr403Cys) in the IVD gene were identified in the patient. His parents were heterozygous carriers. After the treatment with low-leucine diets and L-carnitine for 3 days, the patient showed a significant improvement in symptoms, but he died one week later. It is concluded that the neonates with pneumonia and metabolic decompensation of unknown etiology should be screened for genetic metabolic disease.
Amino Acid Metabolism, Inborn Errors ; diagnosis ; genetics ; Humans ; Infant, Newborn ; Isovaleryl-CoA Dehydrogenase ; deficiency ; genetics ; Male ; Mutation ; Pancytopenia ; etiology

OBJECTIVE: To summarize newborn screening for methionine adenosyltransferase I/III (MAT I/III) deficiency in Quanzhou region of Fujian Province. METHODS: A total of 364 545 neonates were screened for inherited metabolic diseases by tandem mass spectrometry. High-throughput next generation sequencing combined with Sanger sequencing was used to detect potential variants in newborns with MAT I/III deficiency. Pathogenicity of suspected variants was predicted by using MutationTaster and HSF software. RESULTS: Three newborns were identified with MAT I/III deficiency by newborn screening, which yielded an incidence rate of 1 in 121 515. Amino acid and acylcarnitine analysis suggested that the serum methionine of the three patients have increased to various extents. All patients showed normal growth and development during follow-up, and were found to carry MAT1A gene variants including two missense variants [c.776C>T (p.Ala259Val) and c.791G>A (p.Arg264His)] and a synonymous variant [c.360C>T (p.Cys120Cys)]. Among these, c.776C>T (p.Ala259Val) and c.791G>A (p.Arg264His) were known to be pathogenic, whereas c.360C>T (p.Cys120Cys) was a novel variant. Bioinformatics analysis suggested that this variant may alter RNA splicing and affect the structure and function of the MAT1A protein. CONCLUSION A systematic review of newborn screening for MAT I/III deficiency was provided. Discovery of the novel variant has enriched the variant profile of the MAT1A gene and provided a basis for the diagnosis of this disease.
Amino Acid Metabolism, Inborn Errors ; diagnosis ; China ; Genetic Variation ; Humans ; Infant, Newborn ; Methionine Adenosyltransferase ; deficiency ; genetics ; Neonatal Screening

OBJECTIVE: To identify genetic variants among patients with methylmalonic acidemia and provide genetic evidence for prenatal diagnosis. METHODS: Thirty-one probands and their parents were subjected to next generation sequencing (NGS). Suspected variants were verified by Sanger sequencing. RESULTS: 25 probands or their parents were found to harbor previously known pathogenic or likely pathogenic variants, and three probands were found to carry heterozygous MMACHC exonic deletion. The overall diagnostic yield was 90.32%. CONCLUSION NGS can improve the detection rate for methylmalonic acidemia for its accuracy and efficiency, yet the detection of exonic deletion is required to further improve the diagnostic yield. The identification of specific variants provided evidence for prenatal diagnosis.
Amino Acid Metabolism, Inborn Errors/genetics* ; Female ; Heterozygote ; High-Throughput Nucleotide Sequencing ; Humans ; Mutation ; Oxidoreductases ; Pregnancy ; Prenatal Diagnosis

OBJECTIVETo screen and diagnose fatty acid oxidation disorders (FAOD) in high risk children with inborn error of metabolism using tandem mass spectrometry.

METHODSThe study group consisting of 2941 high risk cases of suspected inborn error of metabolism was tested. The acylcarnitines in the dry blood filter papers of patients were tested by tandem mass spectrometry. The diagnosis of FAOD was according to the levels of the acylcarnitines, the clinical symptoms, and other biochemistry study.

RESULTSFourteen patients were diagnosed as FAOD. These patients included one carnitine palmitoyltransferase deficiency I, one carnitine palmitoyltransferase deficiency II, one short-chain acyl-CoA dehydrogenase deficiency, seven medium-chain acyl-CoA dehydrogenase deficiency, two very long-chain acyl-CoA dehydrogenase deficiency, and two multiple acyl-CoA dehydrogenase deficiency.

CONCLUSIONFAOD are not rare in China. Analysis of acylcarnitines levels tested by tandem mass spectrometry is helpful to diagnose FAOD.

Adolescent ; Amino Acid Metabolism, Inborn Errors ; diagnosis ; genetics ; Carnitine ; analogs & derivatives ; chemistry ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Infant, Newborn ; Lipid Metabolism ; physiology ; Lipid Metabolism, Inborn Errors ; diagnosis ; Male ; Mass Spectrometry ; Tandem Mass Spectrometry ; methods