Sialic Acid Storage Disease

**Definition:** Autosomal recessive neurodegenerative disorders caused by lysosomal membrane transport defects that result in accumulation of free sialic acid (N-ACETYLNEURAMINIC ACID) within the lysosomes. The two main clinical phenotypes, which are allelic variants of the SLC17A5 gene, are ISSD, a severe infantile form, or Salla disease, a slowly progressive adult form, named for the geographic area in Finland where the kindred first studied resided.

**Tree numbers:** - C10.228.140.163.100.435.810 - C16.320.565.189.435.810 - C16.320.565.595.554.810 - C18.452.132.100.435.810 - C18.452.648.189.435.810 - C18.452.648.595.554.810

**Synonyms:** - Sialuria