A Family Guide to Non-Oncologic Blood Disorders
Krabbe Disease
What is Krabbe disease? Krabbe disease is a rare inherited degenerative disorder of the central and peripheral nervous system. Krabbe disease is part of a group of genetic disorders called leukodystrophies that are caused by a deficiency of the enzyme Galactocerebro- sidase. When the enzyme is missing, there is a toxic buildup of abnormal fatty materials (lipids), which in turn causes destruction of the myelin sheath. The myelin sheath provides a covering around the nerves that carry signals from the brain to various parts of the body. When the myelin sheath is damaged, the brain cannot communicate with other parts of the body. Krabbe disease is inherited through a defective gene from both parents. Krabbe disease most often affects infants with onset before 6 months, but can occur in adolescence or adulthood. Krabbe disease usually is fatal before age 2, while patients with juvenile or adult onset generally live longer. What are some symptoms of Krabbe disease? The following are the most common symptoms of Krabbe dis- ease. However, each child may experience symptoms differently. Symptoms may include: • Irritability • Unexplained fever • Limb stiffness • Seizures • Feeding difficulties • Vomiting • Slowing of mental and motor development • Muscle weakness • Spasticity • Deafness • Blindness How is Krabbe disease diagnosed? • Magnetic resonance imaging (MRI), an imaging test that uses powerful magnets to create images of the organs and tissues in the body • Blood and urine tests to determine deficiency level of the missing enzyme What tests and procedures will my child need? • Imaging studies of the brain using a computed tomog- raphy (CT) scan or MRI scan, that show an unusual loss of white matter due to the loss of myelin. An MRI can
be suggestive of Krabbe disease, but is generally not accepted as a formal diagnostic tool. • Blood test is done to check for enzyme levels. • Urine test to confirm the presence of sulfatides (a major fat component of the myelin sheath) • Nerve conduction studies to measure the velocity of impulses being sent through the nervous system. When myelin is impaired, the nerve conduction is slower. • Eye examination to look for indications of visual deterioration • Newborn screen testing (only in select states) • Before birth, a mother’s amniotic fluid can be screened for Krabbe disease to look for the missing enzyme. This is not done for every family, but is used for families who have a previous child with Krabbe disease. How is Krabbe disease treated? There are no curative options for symptomatic patients who have the infantile form of the disease. Supportive care is uti- lized to manage irritability and spasticity. Stem cell transplan- tation has been utilized for patients in the presymptomatic phase with an unrelated or cord blood donor. How successful is the treatment? A stem cell transplant can help minimize permanent damage caused by this disease. The transplant provides the most effective results if performed before the onset of symptoms in patients with the infantile form or for patients with juvenile onset Krabbe disease. Children who are symptomatic at the time of transplant often do not show evidence of significant improvement after transplant. Stem Cell Transplant Indications Stem cell transplant is indicated for children who have the infantile form of Krabbe but have not started to show signifi- cant symptoms or patients with the juvenile onset form of the disease.
Krabbe Disease
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