Test Catalog

Test ID: PSY    
Psychosine, Blood Spot

Useful For Suggests clinical disorders or settings where the test may be helpful

Aids in the biochemical diagnosis of Krabbe disease and saposin A cofactor deficiency


Follow-up of individuals affected with Krabbe disease


Follow-up testing after an abnormal newborn screening result for Krabbe disease


This test is not capable of identifying carriers of Krabbe disease.

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive lysosomal storage disorder caused by an enzyme deficiency of galactocerebrosidase (GALC).


Although Krabbe disease is clinically variable, the most common and severe form of the disorder is early infantile onset that presents with rapid neurological regression and results in early death.


This test is a second-tier assay for infants who have abnormal newborn screens with reduced galactocerebrosidase (GALC) activity and can diagnose patients with Krabbe disease or saposin A cofactor deficiency.


Elevations in psychosine support a diagnosis of Krabbe disease; therefore, psychosine quantitation is a useful biomarker in determining if an individual has active disease and can aid in monitoring disease progression or treatment response.


Psychosine is also elevated in saposin A cofactor deficiency, which results in a similar clinical phenotype to Krabbe disease, but patients have normal galactocerebrosidase (GALC) activity.

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Special Instructions Library of PDFs including pertinent information and forms related to the test

Method Name A short description of the method used to perform the test

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

NY State Available Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name Lists a shorter or abbreviated version of the Published Name for a test

Psychosine, BS

Aliases Lists additional common names for a test, as an aid in searching

Krabbe disease