title: Molecular and cellular pathology of very-long-chain acyl-CoA dehydrogenase deficiency.
abstract: BACKGROUND
  Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD) is diagnosed in the US through newborn screening (NBS). NBS often unequivocally identifies affected individuals, but a growing number of variant patterns can represent mild disease or heterozygous carriers.
  
  
  OBJECTIVE
  To evaluate the validity of standard diagnostic procedures for VLCADD by using functional in vitro tools.
  
  
  METHODS
  We retrospectively investigated 13 patient samples referred to our laboratory because of a suspicion of VLCADD but with some uncertainty to the diagnosis. All 13 patients were suspected of having VLCADD either because of abnormal NBS or suggestive clinical findings. ACADVL genomic DNA sequencing data were available for twelve of them. Ten of the patients had an abnormal NBS suggestive of VLCADD, with three samples showing equivocal results. Three exhibited suggestive clinical findings and blood acylcarnitine profile (two of them had a normal NBS and the third one was unscreened). Assay of VLCAD activity and immunoblotting or immunohistologic staining for VLCAD were performed on fibroblasts. Prokaryotic mutagenesis and expression studies were performed for nine uncharacterized ACADVL missense mutations.
  
  
  RESULTS
  VLCAD activity was abnormal in fibroblast cells from 9 patients (8 identified through abnormal NBS, 1 through clinical symptoms). For these 9 patients, immunoblotting/staining showed the variable presence of VLCAD; all but one had two mutated alleles. Two patients with equivocal NBS results (and a heterozygous genotype) and the two patients with normal NBS exhibited normal VLCAD activity and normal VLCAD protein on immunoblotting/staining thus ruling out VLCAD deficiency. Nine pathogenic missense mutations were characterized with prokaryotic expression studies and showed a decrease in enzyme activity and variable stability of VLCAD antigen.
  
  
  CONCLUSIONS
  These results emphasize the importance of functional investigation of abnormal NBS or clinical testing suggestive but not diagnostic of VLCADD. A larger prospective study is necessary to better define the clinical and metabolic ramifications of the defects identified in such patients.
authors.affiliation: Department of Pediatrics, University of Pittsburgh School of Medicine, University of Pittsburgh, Children's Hospital of Pittsburgh of UPMC, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
authors.forename: Manuel
authors.initials: M
authors.lastname: Schiff
authors.forename: Al-Walid
authors.initials: AW
authors.lastname: Mohsen
authors.forename: Anuradha
authors.initials: A
authors.lastname: Karunanidhi
authors.forename: Elizabeth
authors.initials: E
authors.lastname: McCracken
authors.forename: Renita
authors.initials: R
authors.lastname: Yeasted
authors.forename: Jerry
authors.initials: J
authors.lastname: Vockley
mesh_terms: D044942:Acyl-CoA Dehydrogenase, Long-Chain / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D000483:Alleles; D002478:Cells, Cultured; D000080984:Congenital Bone Marrow Failure Syndromes; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D008052:Lipid Metabolism, Inborn Errors / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D028361:Mitochondrial Diseases / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D009135:Muscular Diseases / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D020125:Mutation, Missense; D015997:Neonatal Screening; D017422:Sequence Analysis, DNA
chemical_list: D044942:Acyl-CoA Dehydrogenase, Long-Chain