Galactosialidosis, is caused by the absence of an enzyme called Protective Protein/Cathepsin A (PPCA).
This enzyme works with two other enzymes, B- Galactosidase and Neuraminidase, to break down oligosaccharides. PPCA also helps in protecting the enzymes Galactosidase and Neuraminidase from being broken down in the lysosome. Thus, when PPCA is absent, it also leads to the absence of B-Galactosidase and Neuraminidase.
There are three forms of galactosialidosis which are distinguished by the age at which symptoms develop and the pattern of features.
The early infantile form of galactosialidosis is associated with extensive swelling caused by fluid accumulation before birth (hydrops fetalis), a soft outpouching in the lower abdomen (an inguinal hernia), and an enlarged liver and spleen (hepatosplenomegaly). Additional features of this form include abnormal bone development (dysostosis multiplex) and distinctive facial features that are often described as “coarse.” Some infants have an enlarged heart (cardiomegaly); an eye abnormality called a cherry-red spot, which can be identified with an eye examination; and kidney disease that can progress to kidney failure. Infants with this form usually are diagnosed between birth and 3 months; they typically live into late infancy.
The late infantile form of galactosialidosis shares some features with the early infantile form, although the signs and symptoms are somewhat less severe and begin later in infancy. This form is characterized by short stature, dysostosis multiplex, heart valve problems, hepatosplenomegaly, and “coarse” facial features. Other symptoms seen in some individuals with this type include intellectual disability, hearing loss, and a cherry-red spot. Children with this condition typically develop symptoms within the first year of life. The life expectancy of individuals with this type varies depending on the severity of symptoms.
The juvenile/adult form of galactosialidosis has signs and symptoms that are somewhat different than those of the other two types. This form is distinguished by difficulty coordinating movements (ataxia), muscle twitches (myoclonus), seizures, and progressive intellectual disability. People with this form typically also have dark red spots on the skin (angiokeratomas), abnormalities in the bones of the spine, “coarse” facial features, a cherry-red spot, vision loss, and hearing loss. The age at which symptoms begin to develop varies widely among affected individuals, but the average age is 16. This form is typically associated with a normal life expectancy.
The prevalence of galactosialidosis is unknown; more than 100 cases have been reported.
- • deficiency of cathepsin A
- • Goldberg syndrome
- • lysosomal protective protein deficiency
- • neuraminidase deficiency with beta-galactosidase deficiency
- • PPCA deficiency
There is no cure for galactosialidosis. Treatment is symptomatic and supportive; for example, taking medication to control seizures. Individuals with galactosialidosis are encouraged to 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. No conclusive results are currently available regarding the long term benefits of this treatment.
Medical and Research Information
- • Genetics Home Reference: An excellent description of Galactosialidosis with good references to other information and resources.
- • Clinical Trials: A registry of federally and privately supported clinical trials conducted in the United States and around the world. This site gives information about each trial’s purpose, who may participate, and the location.
- • OMIM: Technical information about the genetics of this disorder. OMIM is a site developed for scientists and medical specialists and contains both general and highly technical information. Access to this site is free.
- • PubMed: The most recent literature.
- • Orphanet: A database dedicated to information on rare diseases and orphan drugs. Access is free of charge.
- • GeneTests: A list of laboratories testing for Galactosialidosis.
Patient Support Groups
- • ISMRD: The international advocate for Glycoprotein Storage Diseases
- • ISMRD’s Facebook page; this page is closed and for families only
- • ISMRD’s public Facebook page.
- • LDNZ: Lysosomal Diseases New Zealand is the support group for families in New Zealand
- • CLIMB: Children Living with Inherited Metabolic Diseases is a United Kingdom support group