Definition:
Schindler Disease is caused by the deficient activity of the lysosomal enzyme, alpha-N-acetylgalactosaminidase (alpha-NAGA). A deficiency of the alpha-NAGA enzyme leads to an accumulation of glycosphingolipids throughout the body. This accumulation of sugars gives rise to the clinical features associated with this disorder.

There are three types of Schindler Disease, characterized by the age of onset and type of physical and mental symptoms. They are Type I (infantile), Type II (adult) and Type III (intermediate).

Symptoms:
In the Type I infantile form, infants will develop normally until about a year old. At this time, the affected infant will begin to lose previously acquired skills involving the coordination of physical and mental behaviors.  Additional neurological and neuromuscular symptoms such as diminished muscle tone, weakness, involuntary rapid eye movements, visual loss, and seizures may become present. With time, the symptoms worsen and children affected with this disorder will experience a decreased ability to move certain muscles due to the muscles’ rigidity. The ability to respond to external stimuli will also decrease.
 
In Type II adult form, symptoms are milder and may not appear until the individual is in his or her 30s. Angiokeratomas, an increased coarsening of facial features, and mild intellectual impairment are likely symptoms.

In Type III intermediate form, symptoms vary and can include to be more severe with seizures and mental retardation, or less severe with delayed speech, a mild autistic-like presentation, and/or behavioral problems.

Inheritance Pattern:
All three forms of Schindler Disease are autosomal recessive disorders.

Diagnosis and Testing:
Schindler disease may be screened for by measuring oligosaccharides in the urine.  If these are found to be increased, specific diagnosis is made by demonstrating reduced activity of the enzyme alpha-NAGA in the blood or a tissue biopsy.  Genetic testing is available to show the mutations in the NAGA gene.  Such molecular testing is the preferred means of making prenatal diagnosis.

Life Expectancy:
Life expectancy for Type I Schindler Disease is between three and four years of age.

Treatment:
There is no cure for Schindler Disease. Treatment is limited to reducing or controlling the symptoms of this disorder by making sure that neurologists, ophthalmologists, and genetic counselors are routinely seen. Neurologists will help to keep seizures or nervous system complications under control. An ophthalmologist can monitor vision loss and, in the case of Type I infantile Schindler Disease, physical and occupational therapists can help the affected individual maintain muscle movement and reduce muscle discomfort.

Patient Groups:
International Society for Mannosidosis & Related Diseases
P.O. Box 328
Dexter, MI 48130
www.mannosidosis.org
tel: (734) 449-8222
fax: (734) 449-2282
Terri Klein, Executive Director
info@ismrd.org