What is the role of genetic testing in the workup of carnitine deficiency?

Updated: Dec 13, 2019
  • Author: Fernando Scaglia, MD, FACMG; Chief Editor: Maria Descartes, MD  more...
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Answer

Molecular diagnosis: Molecular diagnosis provides information on the gene for the carnitine transporter defective in primary carnitine deficiency, which has been cloned (SLC22A5) and can be screened for mutations. Most patients have private mutations. However, the R245X mutation has been found in Taiwanese, Saudi, and Lebanese kindreds. [12] The R245X and V295X mutations are associated with cardiomyopathy as the only clinical phenotype. Phenotypic variability has been observed among patients harboring the same mutations raising the possibility of modifier genes or epigenetic factors as responsible for these differences.

Mutation analysis: The genes for most of the enzymes of fatty acid oxidation that are defective in fatty acid oxidation disorders and may cause secondary carnitine deficiency have been identified, and mutation analysis is available for numerous genes (eg, CPT1, CPT2, VLCAD, TFP, MCAD). Prevalent mutations have been identified in patients with MCAD deficiency (A985G) and LCHAD deficiency (G1528C). In the adult form of CPT-II deficiency, a C439T mutation accounts for 60% of mutations in patients with adult onset.


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