Salla disease

What is Salla Disease?

Salla disease, also called free sialic acid storage disease, is an inherited condition causing a slow, progressive decline in motor and mental skills. Adults with the disease are profoundly disabled, but live normal lifespans. Salla disease belongs to a group of diseases known as lysosomal storage disorders.

Children with Salla disease appear normal at birth, but show poor muscle tone in the first year of life. Delays in their motor and mental skills become more obvious with age. They become spastic and will have difficulty coordinating their voluntary movements. Most will be able to walk in adulthood, though some cannot.

Loss of intellect is progressive over time, beginning in the first or second year of life. Children with Salla disease typically have delayed language skills. By adulthood, all people with Salla disease have profound intellectual and developmental disabilities with IQs between 20 and 40. Most can speak some words in short sentences.

In a more severe form of Salla disease, also called intermediate severe Salla disease, symptoms appear between the ages of 1 and 6 months. Infants have extremely poor muscle tone, growth delay, and may have seizures. Their loss of motor and mental functions are more rapid, and lifespan may be shortened.

How common is Salla Disease?

Salla disease is rare except in Northern Finland, where 1 in 40 people are carriers. Only 30 cases of intermediate severe Salla disease have been documented outside of Finland.

How is Salla Disease treated?

There is no effective treatment for Salla disease other than to address symptoms as they arise. Special education or physical, occupational, or speech therapy may be helpful.

What is the prognosis for a person with Salla Disease?

People with Salla disease have normal lifespans, but all will be profoundly disabled and will have difficulty with movement. Most will be able to walk, but some will not.

Those with the severe form of Salla disease will have a reduced lifespan. The small number of cases known worldwide make an exact prognosis difficult.