Your doctor will conduct a general physical exam and assess signs and symptoms that may indicate a neurological disease. A diagnosis of Krabbe disease is based on a series of tests, which may include the following.
A blood sample and small skin sample (biopsy) will be sent to a laboratory to assess the level of GALC enzyme activity. Very low or no GALC activity level may indicate Krabbe disease.
Although the results help a doctor make a diagnosis, they don't provide evidence of how quickly the disease may progress. For example, very low GALC activity doesn't always mean that the condition will advance rapidly.
Your doctor may order one or more imaging tests that can detect the loss of myelin (demyelination) in affected regions of the brain. These may include:
- Magnetic resonance imaging (MRI), a technology that uses radio waves and a magnetic field to produce detailed 3-D images
- Computerized tomography (CT), a specialized X-ray technology that produces 2-D images
Nerve conduction study
A nerve conduction study assesses the rate at which nerves conduct a signal — essentially how quickly can they send a message. A special device measures the time it takes an electrical impulse to travel from one point on the body to another. When myelin is impaired, nerve conduction is slower.
A genetic test may be done with a blood sample to confirm a diagnosis. There are variant forms of the mutated gene that results in Krabbe disease. The particular type of mutation may provide some clues regarding the expected course of the disease.
In some states, a screening test for Krabbe disease is part of a standard set of assessments for newborns. The initial screening test measures GALC enzyme activity. If the enzyme activity is found to be low, follow-up GALC tests and genetic tests are conducted.
The use of newborn screening tests is relatively new. Researchers are still working to understand how best to use these tests, how well the tests lead to an accurate diagnosis and how well they predict the course of the disease.
June 03, 2014
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