This test detects the GALC gene 30kb deletion. This mutation accounts for approximately 45% of the mutations in the Caucasian population and 35% of the mutation in those with Mexican heritage. When this mutation is found in the homozygous state, it causes the infantile form of Krabbe disease. It causes severe disease in the heterozygous state with another mutation.

Krabbe disease is associated with the demyelination of the nervous system and abnormal globoid cells in the brain. Age of onset is typically in infancy, although other forms occur later in life. The symptoms usually include muscle weakness, irritability, feeding difficulties, fever without infection, developmental delay, stiff posture, vision loss, and seizures. The infantile form of the disease causes death by age 2, and life expectancy is decreased in the later onset forms. The incidence of Krabbe disease is estimated to be ~1 in 100,000.

Gene analysis for the various targeted mutations is performed by polymerase chain reaction and melting curve analysis to detect the mutant and wild type form of the gene. Sequence specific oligonucleotide probes are labeled with fluorescent dyes which hybridize to their complementary sequence target in PCR products. The fluorescence resonance energy transfer (FRET) from one fluorophore to another adjacent fluorophore is measurable and is directly proportional to the amount of target DNA generated during PCR. Allele specific melting curves are generated by slow thermal denaturing of the probe: template hybrid. Melting curves are generated by monitoring fluorescence over the course of denaturation and melting peaks are generated by plotting the inverse derivative of fluorescence versus temperature (−dF/dT).