Salla Disease (Free Sialic Acid Storage Disease)
Summary
Salla disease is a lysosomal storage disorder caused by deficient transport of free sialic acid out of lysosomes. The SLC17A5 gene encodes sialin, the lysosomal membrane transporter for sialic acid. When this transporter is defective, free sialic acid accumulates in lysosomes throughout the body, particularly affecting the brain.
Practical takeaway
Primarily relevant if your partner is of Finnish or northern Swedish descent. Carrier testing is available. Realised does not calculate reproductive risk or advise on reproductive decisions.
Evidence detail
What Carrier Status Means For You
You are not affected. One working copy of SLC17A5 is sufficient. Standard 25/50/25 recessive inheritance applies.
Population Context
Named after the municipality of Salla in northeastern Finland where the condition was first identified. The R39C variant is a Finnish/Swedish founder mutation. Carrier frequency is highest in northeastern Finland (~1 in 40). Part of the Finnish disease heritage.
Limitations
23andMe tests 1 SLC17A5 variant. Other SLC17A5 variants cause the more severe ISSD phenotype. Coverage limited to the Finnish founder mutation.