title: Eight novel MUT loss-of-function missense mutations in Chinese patients with isolated methylmalonic academia.
abstract: BACKGROUND
  Isolated methylmalonic acidemia is a rare autosomal recessive metabolic disorder mostly caused by mutations in the methylmalonyl coenzyme A mutase (MCM) gene (MUT). This study aimed to verify whether missense mutations in MUT in Chinese patients affect the stability and enzymatic activity of MCM.
  
  
  METHODS
  Eight Chinese patients were identified with novel mutations. Plasmids carrying the wild-type and mutated MUT cDNA were constructed and transfected into HEK293T cells for functional analyses. The expression and activity of MCM were determined by western blot and ultra-performance liquid chromatography, respectively.
  
  
  RESULTS
  All patients had high levels of blood propionylcarnitine and urinary methylmalonyl acid. By the end of the study, two patients were lost to follow-up, three died, and three survived with mental retardation. Compared to the wild-type protein, the expression levels of all missense mutations of in vitro MCM protein were decreased (P<0.05) except those for I597R, and the MCM activity of the mutations was reduced in a permissive assay.
  
  
  CONCLUSIONS
  The missense mutations L140P, A141T, G161V, W309G, I505T, Q514K, I597R and G723D affected the stability and enzymatic activity of MCM, indicating that they had a disease-causing capacity.
authors.affiliation: Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Lian-Shu
authors.initials: LS
authors.lastname: Han
authors.affiliation: Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Han
authors.affiliation: Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Zhu-Wen
authors.initials: ZW
authors.lastname: Gong
authors.affiliation: Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai, China. gu_xuefan@163.com.|, Room 801 Sci&Edu Bldg, 1665 Kongjiang Rd, Yangpu District, Shanghai, 200092, China. gu_xuefan@163.com.
authors.forename: Xue-Fan
authors.initials: XF
authors.lastname: Gu
mesh_terms: D000592:Amino Acid Metabolism, Inborn Errors / Q000175:diagnosis* / Q000235:genetics*; D015153:Blotting, Western; D002648:Child; D002675:Child, Preschool; D002681:China; D004252:DNA Mutational Analysis; D005260:Female; D020022:Genetic Predisposition to Disease; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D008765:Methylmalonyl-CoA Mutase / Q000235:genetics*; D020125:Mutation, Missense; D012494:Sampling Studies
chemical_list: D008765:Methylmalonyl-CoA Mutase
keywords: methylmalonic acid; methylmalonic acidemia; methylmalonyl-CoA mutation; missense mutation