Definition:
Galactosialidosis is one of nine identified Glycoprotein Storage Diseases.  The disorder is caused by the lack of an enzyme called Protective Protein/Cathepsin A (PPCA). This enzyme works with two other enzymes, beta-Galactosidase and Neuraminidase to break down long sugar chains, oligosaccharides, in the lysosome.  However, PPCA also protects beta-Galactosidase and Neuraminidase from being broken down in the lysosomes.  Therefore, those stricken with Galactosialidosis are deficient in these enzymes as well.

There are three different types of Galactosialidosis: infantile, late infantile and juvenile/adult.  Each is characterized by the age of onset and type of physical and mental manifestations. The juvenile/adult Galactosialidosis form is the most common of the three forms.

Symptoms:
The onset of infantile Galactosialidosis occurs between birth and three months of age. In the fetus, infants with this type of Galactosialidosis are presented with hydrops, edema, or the accumulation of fluid, . When the affected child is born, edema in various parts of the body and an enlarged liver, spleen, and/or heart is also present. Skeletal changes, especially along the spine and as well as cognitive and motor delay are also present. Kidney function may be impaired as well. 

The onset of late infantile Galactosialidosis is within the first few months of life. Coarse facial features, enlargement of the spleen and liver, and abnormal bone formations, usually in the spine, are also present. A cherry-red spot or clouding of the cornea may occur.  If mental retardation is present, it is generally mild. Deafness may also occur.

The onset of juvenile/adult Galactosialidosis is typically around 16 years of age. Some cases have reported symptoms appearing as late in life of affected individuals, as in their 20s and 30s.  Individuals with juvenile/adult Galactosialidosis are predominantly of Japanese origin. Coarse facial features, spinal cord changes, ataxia, seizures, and declining mental capacities are some of the classic symptoms of this form of the disorder. Cherry-red spots, clouding of the cornea, purplish-red spots on the skin, and vision loss may also be present.

Inheritance Pattern:
Galactosialidosis is an autosomal recessive disorder.

Diagnosis and Testing:
To determine if the patient has Galactosialidosis, a urine test is performed to measure increased levels oligosaccharides, the type of sugar chains in the lysosome that accumulate as a result of the malfunctioning enzyme. A urine test is routinely followed by a blood test or skin biopsy which will show reduced activity of the enzymes B-Galactosidase and Neuraminidase. Prenatal screening is also available to examine B-Galactosidase and Neuraminidase activity in the fetus.  Genetic testing is also available in combination with these diagnostic tests to look for the mutation that causes Galactosialidosis.

Life Expectancy:
Life Expectancy for infantile Galactosialidosis is one year of age or younger. Children with late infantile Galactosialidosis survive through the first and into their second decade, and individuals with  juvenile/adult Galactosialidosis survive into adult life.

Treatment:
There is no cure for Galactosialidosis. Treatment is limited to reducing or controlling the symptoms of this disorder, by for example, taking medication to control seizures. It is encouraged that individuals with Galactosialidosis routinely see their genetic counselors, neurological, ophthalmological, and other specialists as symptoms arise and to keep symptoms controlled.  Bone marrow transplant is under investigation as an experimental therapy.

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