Galactosialidosis Unraveled: Understanding, Diagnosing, and Genetic Testing

Expert Reviewed By: ⁠Dr. Brandon Colby MD

Galactosialidosis is a rare genetic disorder characterized by the deficiency of two enzymes, neuraminidase 1 and beta-galactosidase, which play a crucial role in breaking down complex sugar molecules in the body. This deficiency leads to the accumulation of these molecules in various organs, causing a wide range of symptoms and complications. The adult form of galactosialidosis is the least severe, with symptoms typically appearing in adolescence or adulthood. In this article, we will discuss the importance of understanding, diagnosing, and using genetic testing for galactosialidosis in adults.

Understanding Galactosialidosis in Adults

Galactosialidosis is caused by mutations in the CTSA gene, which provides instructions for producing a protein called protective protein/cathepsin A (PPCA). This protein is essential for the proper functioning of the two enzymes mentioned earlier. When there is a deficiency in PPCA, the enzymes cannot break down complex sugar molecules, leading to their accumulation in the body and causing various symptoms.

Adult galactosialidosis is the mildest form of the disorder, with symptoms often appearing in adolescence or adulthood. These symptoms may include muscle weakness, impaired coordination, seizures, hearing loss, and vision problems. Some affected individuals may also develop angiokeratomas, which are small, dark red spots on the skin.

Diagnosing Galactosialidosis

Diagnosing galactosialidosis can be challenging due to the rarity of the disorder and the variability of symptoms. A combination of clinical examination, biochemical tests, and imaging studies may be used to establish a diagnosis. Biochemical tests involve measuring the activity of the enzymes neuraminidase 1 and beta-galactosidase in blood or skin cells. Reduced enzyme activity may indicate the presence of galactosialidosis.

Imaging studies, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans, may be performed to assess the extent of organ involvement and to rule out other potential causes of the patient’s symptoms. A definitive diagnosis can be made through genetic testing, which involves analyzing the patient’s DNA for mutations in the CTSA gene.

Genetic Testing for Galactosialidosis

Genetic testing can be a valuable tool for diagnosing galactosialidosis, as well as for providing information about the specific genetic cause of the disorder. This information can be helpful in several ways:

Confirming a Diagnosis

As mentioned earlier, genetic testing can be used to confirm a diagnosis of galactosialidosis by identifying mutations in the CTSA gene. This can be particularly helpful in cases where the clinical presentation is atypical or the biochemical tests are inconclusive.

Identifying Carrier Status

Galactosialidosis is inherited in an autosomal recessive manner, meaning that both copies of the CTSA gene must be mutated for a person to be affected by the disorder. Individuals with only one mutated copy of the gene are considered carriers and are generally asymptomatic. Genetic testing can be used to identify carriers, who may be at risk of having a child with galactosialidosis if their partner is also a carrier.

Guiding Treatment and Management

Although there is currently no cure for galactosialidosis, identifying the specific genetic cause of the disorder can help guide treatment and management strategies. For example, enzyme replacement therapy (ERT) is being investigated as a potential treatment for galactosialidosis, and knowing the specific mutation may help determine whether a patient is a candidate for ERT or other experimental therapies.

Providing Information for Family Planning

Genetic testing can provide valuable information for couples who are planning to have children and are concerned about the risk of galactosialidosis. By identifying carriers and understanding the specific genetic cause of the disorder, couples can make informed decisions about their reproductive options, such as pursuing in vitro fertilization (IVF) with preimplantation genetic diagnosis (PGD) to select embryos without the mutated gene.

In conclusion, understanding, diagnosing, and using genetic testing for galactosialidosis in adults is essential for providing the best possible care for affected individuals and their families. Early diagnosis and appropriate management can help improve the quality of life for those living with this rare genetic disorder.

About The Expert Reviewer

Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of  and the author of ⁠⁠Outsmart Your Genes.

Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (⁠⁠ACMG), an Associate of the American College of Preventive Medicine (⁠⁠ACPM), and a member of the National Society of Genetic Counselors (⁠NSGC)