Krabbe disease- atypical- due to Saposin A deficiency

Overview

Krabbe disease, atypical, due to saposin A deficiency: An inherited biochemical disorder which results in neurological regression within a few months of birth. Death usually occurs during the first few years of life. The disorder is similar to Krabbe disease but is differentiated by the genetic origin of the biochemical defect. Krabbe disease involves a defect in the galactocerebrosidase gene whereas atypical Krabbe disease involves a defect in the prosaposin gene which causes a deficiency of saposin A. Krabbe disease is a rare genetic disorder of the nervous system. It is a type of leukodystrophy.

Symptoms

The symptoms of Krabbe disease usually begin before the age of 1 year (the infantile form). Initial signs and symptoms typically include irritability, muscle weakness, feeding difficulties, episodes of fever without any sign of infection, stiff posture, and slowed mental and physical development. As the disease progresses, muscles continue to weaken, affecting the infant's ability to move, chew, swallow, and breathe. Affected infants also experience vision loss and seizures.

Less commonly, onset of Krabbe disease can occur in childhood, adolescence, or adulthood (late-onset forms). Visual problems and walking difficulties are the most common initial symptoms in this form of the disorder, however, signs and symptoms vary considerably among affected individuals.

Causes

Mutations in the GALC gene cause Krabbe disease. These mutations cause a deficiency of the enzyme galactosylceramidase. This deficiency leads to a progressive loss of myelin that covers many nerves. Without myelin, nerves in the brain and other parts of the body cannot function properly, leading to the signs and symptoms of Krabbe disease.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

The GALC gene.

Prevention

Genetic counseling is recommended for persons with a family history of Krabbe disease who are considering having children. A blood test can be done to see if you carry the gene for Krabbe disease. Prenatal tests (amniocentesis or chorionic villus sampling) can be done to screen a developing baby for this condition.

Diagnosis

The signs and symptom information on this page attempts to provide a list of some possible signs and symptoms of Krabbe disease, atypical, due to saposin A deficiency. This medical information about signs and symptoms for Krabbe disease, atypical, due to saposin A deficiency has been gathered from various sources, may not be fully accurate, and may not be the full list of Krabbe disease, atypical, due to saposin A deficiency signs or Krabbe disease, atypical, due to saposin A deficiency symptoms. Furthermore, signs and symptoms of Krabbe disease, atypical, due to saposin A deficiency may vary on an individual basis for each patient. Only your doctor can provide adequate diagnosis of any signs or symptoms and whether they are indeed Krabbe disease, atypical, due to saposin A deficiency symptoms.

Prognosis

The outcome is likely to be poor. On average, infants with early-onset cases die before age 2. People who develop the disease at a later age have survived into adulthood with nervous system disease.

Treatment

There is no specific treatment for Krabbe disease. Some people have had a bone marrow transplant in the early stages of the disease, but this treatment has risks.

Resources

http://ghr.nlm.nih.gov/condition/krabbe-disease