Humans ; Amino Acid Metabolism, Inborn Errors/genetics* ; Haploinsufficiency

OBJECTIVE: To carry out Sanger sequencing for MMACHC gene variants among 65 Chinese pedigrees affected with combined methylmalonic aciduria and homocysteinemia, and summarize their genetic and clinical characteristics and prognosis. METHODS: Clinical characteristics of the 65 children identified with Methylmalonic acidemia and homocysteinemia at the Children's Hospital Affiliated to Zhengzhou University (Zhengzhou Children's Hospital) from April 2017 to April 2022 were selected as the study subjects. Potential variants of the MMACHC gene were detected by direct sequencing of the PCR products. RESULTS: The median age of the 65 children was 3 months (14 days to 17 years old). These included 28 cases (43.08%) from neonatal screening, 11 cases (16.92%) with a history of jaundice, and 9 cases (13.85%) with various degrees of anemia. The main clinical symptoms included development delay, slow growth, epilepsy, hydrocephalus, lethargy, feeding difficulty, regression or decline in motor ability, recurrent respiratory infections, anemia, jaundice, respiratory and heart failures, hydrocephalus, limb weakness, and hypertension. Blood and urine tandem mass spectrometry screening has revealed increase of methylmalonic acid, propionyl carnitine, propionyl carnitine/acetylcarnitine ratio, and propionyl carnitine/free carnitine ratio to various extents, and blood homocysteine was increased in all patients. The detection rate of genetic variants was 98.46% (128/130), and in total 22 types of MMACHC gene variants were detected. The most common ones have included c.609G>A (W203X) (58/128), c.658-660del (K220del) (19/128), and c.80A>G (Q27A) (16/128). Two novel variants have been identified, namely c.565C>T (p.R189C) and c.624_ 625delTG (p.A208Afs), which were respectively predicted as likely pathogenic (PM2_Supporting+PM3+PP2+PP3) and pathogenic (PVS1+PM2_Supporting+PM3+PP2) based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). Exon 4 had the highest frequency for the detection. CONCLUSION Identification of MMACHC gene variants has confirmed the diagnosis in the children, among which the c.609G>A variant has the highest frequency. Discovery of the new variants has enriched the mutational spectrum of the MMACHC gene.
Humans ; Amino Acid Metabolism, Inborn Errors/genetics* ; Hydrocephalus ; Oxidoreductases

Amino Acid Metabolism, Inborn Errors ; Humans ; Infant, Newborn ; Isovaleryl-CoA Dehydrogenase ; deficiency ; Male ; Metabolism, Inborn Errors ; physiopathology

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

We report the first two diagnosed cases of Glutaric Aciduria Type I (GA I) in the Philippines. The diagnosis was confirmed by urinary organic acid analysis by Gas Chromatography-Mass Spectrometry (GC-MS) which showed the characteristic metabolites for GA I. Review of their clinical features showed macrocephaly, developmental delay, seizures, dystonia and choreoathetotic posturing. Cranial CT scan findings were also compatible with previously reported cases. This paper emphasizes the usefulness of locally available biochemical tools in the diagnosis of inborn errors of metabolism as well as the importance of clinical recognition of these disorders.
Human ; Male ; Female ; Child Preschool ; Infant ; MULTIPLE ACYL COENZYME A DEHYDROGENASE DEFICIENCY ; CONGENITAL, HEREDITARY, AND NEONATAL DISEASES AND ABNORMALITIES ; GENETIC DISEASES, INBORN ; METABOLISM, INBORN ERRORS ; AMINO ACID METABOLISM, INBORN ERRORS

OBJECTIVETo detect the pathogenic mutation in a patient with methylmalonic acidemia using IonTorrent Personal Genome Machine (PGM) and assess the feasibility of such technology for analyzing complex monogenic diseases.

METHODSPeripheral blood sample was collected from the patient. Genomic DNA was isolated using a standard method and subjected to targeted sequencing using an Ion Ampliseq Inherited Disease Panel. DNA fragment was ligated with a barcoded sequencing adaptor. Template preparation, emulsion PCR, and Ion Sphere Particles enrichment were carried out using the Ion One Touch system. Data from the PGM runs were processed using Ion Torrent Suite 3.2 software to generate sequence reads. All variants were filtered against dbSNPl37. DNA sequences were visualized with an Integrated Genomics Viewer.

RESULTSAfter data analysis and database filtering, a previously reported nonsense mutation, c.586C>T (p.R196X), and a novel mutation c.898C>T (p.R300X) were identified in the MMAA gene in this patient. Both mutations were verified by conventional Sanger sequencing.

CONCLUSIONPathogenic MMAA mutations have been identified in a patient with methylmalonic acidemia. This new-generation targeted sequencing on the PGM sequencers can be applied for genetic diagnosis of hereditary diseases.

Amino Acid Metabolism, Inborn Errors ; complications ; therapy ; Anemia, Macrocytic ; etiology ; Humans ; Infant ; Male

Amino Acid Metabolism, Inborn Errors ; genetics ; Female ; Glycine N-Methyltransferase ; deficiency ; genetics ; Humans ; Infant, Newborn ; Mutation

Amino Acid Metabolism, Inborn Errors ; urine ; Female ; Glutarates ; urine ; Humans ; Infant ; Male

Adolescent ; Amino Acid Metabolism, Inborn Errors ; complications ; Child ; Female ; Humans ; Male ; Mental Disorders ; etiology