title: Arginine-Glycine Amidinotransferase Deficiency and Functional Characterization of Missense Variants in GATM.
abstract: Arginine-glycine amidinotransferase (GATM) deficiency is an autosomal-recessive disorder caused by pathogenic variants in GATM. Clinical features include intellectual disability, hypotonia, and myopathy. Due to normal neurodevelopment in asymptomatic individuals on creatine monotherapy, GATM deficiency is a good candidate for newborn screening. To determine the carrier frequency of GATM deficiency, we performed functional characterization of rare missense variants in GATM reported as heterozygous in the Exome Variant Server database. To assess phenotype and genotype correlation, we developed a clinical severity scoring system. Two patients with mild phenotype had a nonsense missense variant. Severe phenotype was present in patients with missense as well as truncating variants. There seems to be no phenotype and genotype correlation. We cloned a novel GATM transcript. We found seven missense variants retaining 0% of wild-type GATM activity indicating putative pathogenicity. Based on our study results, high Genomic Evolutionary Rate Profiling conservation score, conserved amino acid substitution in species, and low allele frequency in exome databases would be the most sensitive in silico analysis tools to predict pathogenicity of missense variants. We present first study of the functional characterization of missense variants in GATM as well as clinical severity score of patients with GATM deficiency.
authors.affiliation: Genetics and Genome Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 1×8, Canada.
authors.forename: Caro-Lyne
authors.initials: CL
authors.lastname: DesRoches
authors.affiliation: Genetics and Genome Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 1×8, Canada.
authors.forename: Theodora
authors.initials: T
authors.lastname: Bruun
authors.affiliation: Genetics and Genome Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 1×8, Canada.
authors.forename: Peixiang
authors.initials: P
authors.lastname: Wang
authors.affiliation: Genetics and Genome Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 1×8, Canada.|Genome Diagnostics, Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, M5G 1×8, Canada.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Marshall
authors.affiliation: Genetics and Genome Biology Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 1×8, Canada.|Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, M5G 1×8, Canada.
authors.forename: Saadet
authors.initials: S
authors.lastname: Mercimek-Mahmutoglu
mesh_terms: D000293:Adolescent; D000328:Adult; D000579:Amidinotransferases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D000592:Amino Acid Metabolism, Inborn Errors / Q000235:genetics* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003001:Cloning, Molecular; D002658:Developmental Disabilities / Q000235:genetics / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000235:genetics* / Q000378:metabolism; D008297:Male; D020125:Mutation, Missense; D013064:Speech Disorders / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
chemical_list: D000579:Amidinotransferases; C020681:glycine amidinotransferase
keywords: Exome Variant Server; GATM; arginine-glycine amidinotransferase; carrier frequency; missense variants; site-directed mutagenesis