Inborn Errors of Metabolism
SLC22A5 Gene Sequencing

SLC22A5 Gene Sequencing (Primary Carnitine Deficiency)

Gene Tested



Carnitine deficiency, systemic primary (CDSP), also known as Carnitine uptake deficiency (CUD)


Carnitine deficiency (CDSP), also known as carnitine uptake deficiency (CUD), is a disorder of fatty acid oxidation that is inherited in an autosomal recessive manner. The physical presentations of CDSP, typically manifested under conditions of fasting or illness, may include failure to thrive, encephalopathy, cardiomyopathy, respiratory insufficiency, vomiting, skeletal muscle weakness, and hypoglycemia. CDSP shows variability amongst individuals, even those with the same genotype. Symptoms may present from infancy through adulthood.


• Confirmation of diagnosis in a symptomatic individual 
• Abnormal newborn screen or acylcarnitine profile suggesting CDSP/CUD 

Testing Methodology 

PCR-based sequencing of entire coding region, intron/exon boundaries, as well as known pathogenic variants (HGMD 2017.3) in the promoter and deep intronic regions of the specified gene(s).

Sensitivity and Limitations

The analytical sensitivity of DNA sequencing is over 99% for the detection of nucleotide base changes, small deletions and insertions in the regions analyzed. Variants in regulatory regions and non-reported variants in untranslated regions may not be detected by this test. Large deletions/ duplications, large insertions and other complex genetic events will not be identified using sequencing methodology. 

Turn-Around Time

14 days

CPT Codes


How to Order

Testing for this gene is also available as part the Metaboseq Gene Sequencing panel by next-generation sequencing. Deletion/duplication analysis and targeted variant analysis is also available for this gene. Download Inborn Errors of Metabolism requisition.



El-Hattab, A. W. (2012). Systemic Primary Carnitine Deficiency. GeneReviews. R. A. Pagon, T. D. Bird, C. R. Dolan, K. Stephens and M. P. Adam. Seattle (WA).

El-Hattab, A. W., F. Y. Li, et al. (2010). Maternal systemic primary carnitine deficiency uncovered by newborn screening: clinical, biochemical, and molecular aspects. Genet Med 12(1): 19-24.
Lee, N. C., N. L. Tang, et al. (2010). Diagnoses of newborns and mothers with carnitine uptake defects through newborn screening. Mol Genet Metab 100(1): 46-50.

Lee NC. et al (2010) Diagnoses of newborns and mothers with carnitine uptake defects through newbornscreening. Mol Genet Metab. 2010 May;100(1):46-50. doi: 10.1016/j.ymgme.2009.12.015. Epub

Li, F. Y., A. W. El-Hattab, et al. (2010). Molecular spectrum of SLC22A5 (OCTN2) gene mutations detected in 143 subjects evaluated for systemic carnitine deficiency. Hum Mutat 31(8): E1632-1651.

Schimmenti, L. A., E. A. Crombez, et al. (2007). Expanded newborn screening identifies maternal primary carnitine deficiency. Mol Genet Metab 90(4): 441-445.