Improvement of regressive autism symptoms in a child with TMLHE deficiency following carnitine supplementation

Am J Med Genet A. 2015 Sep;167A(9):2162-7. doi: 10.1002/ajmg.a.37144. Epub 2015 May 5.


Disorders of carnitine biosynthesis have recently been associated with neurodevelopmental syndromes such as autism spectrum disorder (ASD). A 4-year-old male with autism and two episodes of neurodevelopmental regression was identified to have a mutation in the TMLHE gene, which encodes the first enzyme in the carnitine biosynthesis pathway, and concurrent carnitine deficiency. Following carnitine supplementation, the patient's regression ended, and the boy started gaining developmental milestones. This case report suggests that deficits in carnitine biosynthesis may be responsible for some cases of regression in individuals with ASD, and that testing for the respective biochemical pathway should be considered. Furthermore, this case suggests that carnitine supplementation may be useful in treating (and potentially preventing) regressive episodes in patients with carnitine deficiency. Further work to better define the role of disorders of carnitine biosynthesis in autism spectrum disorder is warranted.

Keywords: TMLHE; autism spectrum disorder; carnitine; developmental delay; regression.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autism Spectrum Disorder / genetics*
  • Autistic Disorder / genetics*
  • Cardiomyopathies / genetics*
  • Carnitine / deficiency*
  • Carnitine / genetics
  • Child Development Disorders, Pervasive / genetics
  • Child, Preschool
  • Dietary Supplements
  • Humans
  • Hyperammonemia / genetics*
  • Male
  • Muscular Diseases / genetics*


  • Carnitine

Supplementary concepts

  • Systemic carnitine deficiency