What is Krabbe Disease?
Krabbe Disease is an extremely serious and often fatal inherited pathological condition of the brain in which the entire myelin sheath, a structure which lies above the nerve cells and protects it is destroyed throughout the nervous system. The symptoms of Krabbe Disease may start to become evident by the time a bay is six months of age which rapidly progresses and the baby succumbs to this disease by the age of 2 at maximum. In some cases, this condition is seen to develop in older children and adults but the symptoms then produced vary greatly.
Krabbe Disease does not have a cure and treatment for this condition is totally symptomatic and supportive making the child or the patient as comfortable as possible, although with the advancement in medical science stem cell transplant has shown some promise in treating infants with Krabbe Disease but this needs to be done if the diagnosis gets confirmed before the onset of symptoms. In the United States, one in a hundred thousand births is born with Krabbe Disease.
What Causes Krabbe Disease?
Krabbe Disease is an inherited condition and is caused by mutation in gene GALC which results in complete destruction of the myelin sheath throughout the nervous system. Once the myelin sheath is destroyed the nerve cells are not able to function properly leading to variety of complications. Krabbe Disease is an autosomal recessive disease meaning that a copy of the defective gene needs to be inherited from each parent for the baby to get this disease.
What are the Symptoms of Krabbe Disease?
As stated above, the symptoms of Krabbe Disease start to become apparent by the time the child is six months of age. The symptoms appear gradually at onset but then they rapidly progress. Some of the symptoms of Krabbe Disease are:
- For Infants
- Feeding difficulties
- Unexplained crying
- Extreme irritability
- Fever without any clear etiology
- Decreased alertness
- Developmental delays
- Muscle spasms
- Poor head control
- Frequent episodes of vomiting.
As the disease condition progresses symptoms include
- Developmental regression
- Gradual loss of hearing and vision
- Stiff muscles
- Stiff posture
- Gradual loss of the ability to swallow and breathe.
When Krabbe Disease develops in an older child or an adult, the symptoms are entirely different and include:
- Progressive vision loss
- Gait ataxia
- Poor focus and thinking
- Loss of manual dexterity
- Muscles weakness.
Thus it can be said that if Krabbe Disease is diagnosed in an infant then there are minimal chances of the child surviving which is not the case if this disease occurs in an adult.
How is Krabbe Disease Diagnosed?
For a diagnosis of Krabbe Disease, the doctor will begin with taking a history of the child and observe for signs and symptoms displayed by the child. In case of Krabbe Disease is suspected, then laboratory studies will be done where a blood sample will be taken and sent for analysis to look for the level of GALC enzyme which in cases of Krabbe Disease will be very low to absent. Once Krabbe Disease is suspected, it becomes important to try to confirm the diagnosis and find out whether the disease progression is going to be rapid and fast or not.
For this, radiological studies will be ordered in the form of MRI or CT scan of the brain which will clearly show demyelination or loss of myelin sheath in the brain. This will show the extent and progression of the disease and confirm the diagnosis of Krabbe Disease. A nerve conduction study may also be performed to check on the rate at which the nerves are sending signals through and from the brain and whether there is any abnormality in the functioning of the nerves. In cases of Krabbe Disease, the nerve conductions will be very slow. A genetic test may be done to look for mutation in the GALC gene and if present will confirm the diagnosis of Krabbe Disease.
How is Krabbe Disease Treated?
For infants who have already developed symptoms of Krabbe Disease, as of yet there is no cure and the treatments are purely symptomatic and aimed at keeping the child as comfortable as possible. For symptomatic treatment, the infant will be given anticonvulsants for seizure control. Medications will be given for control of muscle spasms. For slowing down the process of decreasing muscle tone, physical therapy will also be given to the child. It will be made sure that the child is given ample amount of nutritional support as and when the child loses the ability to swallow. In these cases, foods and nutritional supplements can be given through gastric tubes.
On the other hand, older children who develop Krabbe Disease may be given physical and occupational therapy to help with decreasing muscle tone and make the child as independent as possible.
Stem Cell Transplantation. This is one of the newest forms of treatment for Krabbe Disease and has shown some promise especially in infants if done before the onset of symptoms. The stem cells contain microglias that are special cells which tend to reside in the nervous system. Once stem cell transplantation from a healthy donor is done, then these microglias start accumulating in the nervous system and produce healthy GALC enzyme which helps in formation of myelin sheaths. This may greatly slow down the progression of Krabbe Disease. Children receiving stem cell transplantation have significantly slowed progression of Krabbe Disease but still experience great deal of difficulties especially with walking and speech.
What is the Prognosis of Krabbe Disease?
The overall prognosis for Krabbe Disease is very grim as the disease progresses very rapidly. On an average an infant with a confirmed diagnosis of Krabbe Disease can survive a maximum of two years. In older children, the prognosis is a bit better but ultimately they also succumb within 6-7 years of diagnosis of Krabbe Disease.