Neuraminidase Deficiency with... Health Article

Prenatal diagnosis

Galactosialidosis may be diagnosed prenatally. In at-risk fetuses, cultured fetal cells from the amniotic fluid (amniocytes), obtained by amniocentesis, or cultured chorionic villi cells, obtained by chorionic villi sampling (CVS) in the early weeks of pregnancy, may be tested for neuraminidase and beta-galactosidase activities. Furthermore, the enzymatic activities of PPCA can be measured in amniocytes and chorionic villi. PPCA activity is normally very high in these cells and low activity is an indication of an affected fetus. However, since carriers of a single mutated PPGB gene do not have symptoms of galactosialidosis, it may be difficult to recognize an at-risk fetus unless there is a family history of the disorder.

Treatment and management

At present, there is no treatment for neuraminidase deficiency with beta-galactosidase deficiency. Rather, attempts are made to manage individual symptoms. Myoclonic seizures, in particular, are very difficult to control. Bone marrow transplantation is being studied as a treatment for severe galactosialidosis.

Prognosis

The prognosis for individuals with this disorder varies greatly depending on the specific genetic mutation, which determines the age of onset and severity of the disease. Individuals with mild forms of galactosialidosis may have nearly normal life expectancies. However, the early-infantile form of galactosialidosis usually results in death shortly after birth.

BOOKS

Saito, M., and R. K. Yu. "Biochemistry and Function of Sialidases." In Biology of the Sialic Acids. Edited by A. Rosenberg, 7–67. New York: Plenum Press, 1995.

Thomas, G. H., and A. L. Beaudet. "Disorders of Glycoprotein Degradation and Structure: Alpha-mannosidosis, Beta-mannosidosis, Fucosidosis, Sialidosis, Aspartylglucosaminuria and Carbohydrate-deficient Glycoprotein Syndrome." In The Metabolic and Molecular Bases of Inherited Disease. Edited by C. R. Scriver, A. L. Beaudet, W. S. Sly, and D. Valle, 2529–61. New York: McGraw Hill, Inc., 1995.

PERIODICALS

Hiraiwa, M. "Cathepsin A/Protective Protein: An Unusual Lysosomal Multifunctional Protein." Cellular and Molecular Life Sciences 56 (December 1999): 894–907.

ORGANIZATIONS

The International Society for Mannosidosis and Related Diseases. 3210 Batavia Avenue, Baltimore, MD 21214. (410) 254-4903. info@mannosidosis.org. <http://www.mannosidosis.org>.

United Leukodystrophy Foundation. 2304 Highland Drive, Sycamore, IL 60178. (815) 895-3211. (800) 728-5483. ulf@tbcnet.com. <http://www.ulf.org/>.

WEBSITES

Murphy, Paul. "Lysosomal Storage Diseases: A Family Sourcebook." Human Genetic Disease: A Layman's Approach. <http://mcrcr2.med.nyu.edu/murphp01/lysosome/bill1a.htm>.

Margaret Alic, PhD