title: Should metabolic diseases be systematically screened in nonsyndromic autism spectrum disorders?
abstract: BACKGROUND
  In the investigation of autism spectrum disorders (ASD), a genetic cause is found in approximately 10-20%. Among these cases, the prevalence of the rare inherited metabolic disorders (IMD) is unknown and poorly evaluated. An IMD responsible for ASD is usually identified by the associated clinical phenotype such as dysmorphic features, ataxia, microcephaly, epilepsy, and severe intellectual disability (ID). In rare cases, however, ASD may be considered as nonsyndromic at the onset of a related IMD.
  
  
  OBJECTIVE
  To evaluate the utility of routine metabolic investigations in nonsyndromic ASD.
  
  
  METHODS
  We retrospectively analyzed the results of a metabolic workup (urinary mucopolysaccharides, urinary purines and pyrimidines, urinary creatine and guanidinoacetate, urinary organic acids, plasma and urinary amino acids) routinely performed in 274 nonsyndromic ASD children.
  
  
  RESULTS
  The metabolic parameters were in the normal range for all but 2 patients: one with unspecific creatine urinary excretion and the other with persistent 3-methylglutaconic aciduria.
  
  
  CONCLUSIONS
  These data provide the largest ever reported cohort of ASD patients for whom a systematic metabolic workup has been performed; they suggest that such a routine metabolic screening does not contribute to the causative diagnosis of nonsyndromic ASD. They also emphasize that the prevalence of screened IMD in nonsyndromic ASD is probably not higher than in the general population (<0.5%). A careful clinical evaluation is probably more reasonable and of better medical practice than a costly systematic workup.
authors.affiliation: APHP, Reference Center for Inherited Metabolic Disease, Hôpital Robert Debré, Paris, France. manuel.schiff@rdb.aphp.fr
authors.forename: Manuel
authors.initials: M
authors.lastname: Schiff
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Benoist
authors.forename: Sofiane
authors.initials: S
authors.lastname: Aïssaoui
authors.forename: Odile
authors.initials: O
authors.lastname: Boespflug-Tanguy
authors.forename: Odile
authors.initials: O
authors.lastname: Boepsflug-Tanguy
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Mouren
authors.forename: Hélène Ogier
authors.initials: HO
authors.lastname: de Baulny
authors.forename: Richard
authors.initials: R
authors.lastname: Delorme
mesh_terms: D002648:Child; D002659:Child Development Disorders, Pervasive / Q000150:complications*; D003710:Demography; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008659:Metabolic Diseases / Q000150:complications* / Q000175:diagnosis*; D013577:Syndrome