Test Indications: Preferred test to evaluate for a possible diagnosis of galactosemia, carrier detection, and follow-up of abnormal newborn screening results. Galactose-1-phosphate uridyltransferase (GALT) deficiency is the classical and most common cause of galactosemia.
 
The complete or near-complete deficiency of GALT enzyme is life threatening if left untreated. Complications in the neonatal period include failure to thrive, liver failure, sepsis and death; even with survival, long-term intellectual disability can occur. Galactosemia is treated by a galactose-restricted diet which allows for rapid recovery from the acute symptoms.
 
THIS IS A REFLEX TEST (Mayo Clinic Laboratories).
Any specimen where GALT enzyme activity is less than 24.5 nmol/h/mg of hemoglobin will be analyzed for the presence of 14 mutations associated with classic galactosemia, as well as the 2 variants (Duarte and Los Angeles).
 
A PCR-based assay utilizing Sequenom Mass Array platform is used to test for the presence of the following 14 mutations in the GALT gene:
-119_-116delGTCA, D98N, S135L, T138M, M142K, F171S, Q188R, L195P, Y209C, K285N, N314D, Q344K, c.253-2A>G and 5 kb deletion.
 
This assay  will not detect all mutations that cause galactosemia. Therefore, the absence of a detectable mutation does not rule out the possibility that an individual is a a carrier of or affected with this disease.
 
Restricted to Manitoba Medical Geneticists, Gastro-Enterologists, Neonatalogists/Pediatrics
 
For questions/help: please communicate with the biochemical geneticist.