Salla disease

Salla disease, also known as Sialic Acid Storage Disease, Finnish type, is a rare autosomal recessive lysosomal storage disorder characterized by the accumulation of free sialic acid in lysosomes. It is part of a group of disorders known as the lysosomal storage diseases. Salla disease primarily affects the nervous system, leading to physical and mental impairment. It was first identified in the Salla region of Finland, where it has the highest prevalence, but it has since been diagnosed in individuals worldwide.

Symptoms and Signs

The symptoms of Salla disease typically manifest in infancy or early childhood. They include:

• Hypotonia (reduced muscle tone)
• Developmental delay and later, intellectual disability
• Ataxia (impaired balance and coordination)
• Nystagmus (involuntary eye movement)
• Seizures in some cases
• Speech difficulties

As the disease progresses, individuals may experience further neurological deterioration, although the rate of progression can vary widely among affected individuals.

Causes

Salla disease is caused by mutations in the SLC17A5 gene, which encodes a protein involved in the transport of sialic acid out of lysosomes. Mutations in this gene lead to the accumulation of sialic acid within lysosomes, disrupting normal cellular function and leading to the symptoms of the disease.

Diagnosis

Diagnosis of Salla disease involves a combination of clinical evaluation, biochemical tests to measure the levels of free sialic acid in urine, and genetic testing to identify mutations in the SLC17A5 gene.

Treatment

There is currently no cure for Salla disease. Treatment is symptomatic and supportive, focusing on managing symptoms and improving quality of life. This may include physical therapy, speech therapy, and medications to manage seizures and other symptoms.

Epidemiology

Salla disease is most common in individuals of Finnish descent, particularly those from the Salla region, but it has been identified in various ethnic groups worldwide. The exact prevalence is unknown, but it is considered a rare disease.

Research

Research into Salla disease is focused on understanding the underlying mechanisms of the disease and developing effective treatments. Gene therapy and enzyme replacement therapy are areas of interest, but these approaches are still in the experimental stages.