Salla Disease

Salla disease (SD) is the mildest of the sialic storage diseases, which are inherited disorders characterized by progressive neurological problems. Infants with Salla disease appear normal at birth and then develop low muscle tone in the first year of life. As they grow, they exhibit developmental delay, movement and balance problems, and intellectual disability. Later they develop muscle stiffness, seizures, and involuntary movements of the limbs. Individuals with Salla disease usually survive into adulthood but may become nonverbal and unable to walk as they age. There is no cure for Salla disease; however medical surveillance and care may help to improve some symptoms and overall condition of life. Salla disease is caused by pathogenic variants in the SLC17A5 gene.

Salla disease is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

There are generally no signs or symptoms associated with being a carrier for Salla disease. However, the risk to have a child affected with Salla disease is increased. Testing of reproductive partners is recommended for carriers of Salla disease.

Salla disease is a rare disease with only about 150 reported cases. The majority of these cases are in Finland and Sweden; however cases have been reported outside of this region.

Genetics Home Reference: Sialic acid storage disease (http://ghr.nlm.nih.gov/)
Genetic Alliance: Salla disease (http://www.diseaseinfosearch.org/)

OMIM [SD: 604369] (http://www.ncbi.nlm.nih.gov/omim)
Gene Reviews: Free Sialic Acid Storage Disorders (http://www.ncbi.nlm.nih.gov/books/NBK1116/)

• Full gene sequencing