Test ID: PSYCF    
Psychosine, Spinal Fluid

Aids in the biochemical diagnosis of Krabbe disease using cerebrospinal fluid specimens

Follow-up of individuals affected with Krabbe disease

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

Monitoring of individuals at risk to develop late onset Krabbe disease

Monitoring of individuals with Krabbe disease after hematopoietic stem cell transplantation

This test is used as a biomarker of Krabbe disease for individuals with reduced galactocerebrosidase (GALC) activity and for monitoring of patients with Krabbe disease and Saposin A cofactor deficiency. In cerebrospinal fluid (CSF), psychosine is typically ordered when CSF is collected primarily to determine protein content in a patient at risk of or monitored for the development of signs of Krabbe disease.

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

Krabbe disease is clinically variable and infantile-onset Krabbe disease is the most severe variant with rapid neurological regression resulting in early death.

Elevations in psychosine support a diagnosis of Krabbe disease; therefore, psychosine quantitation is a useful biomarker in determining if an individual has active disease. In addition, psychosine may be a valuable biomarker to monitor disease progression, or treatment response.

Psychosine may also be elevated in Saposin A cofactor deficiency, which results in a similar clinical phenotype to Krabbe disease, but patients typically have normal GALC activity in vitro.

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