[MIM 269 920, 604 369]

Very rare, except in Northern Finland where the frequency of carriers is estimated at 1/40. Autosomal recessive transmission of a mutation of the ARSLC17A5 gene (6p13). Overload in free sialic acid due to the failure of a carrier of the lysosomal membrane (sialine) ensuring the release of sialic acid (or N-acetylneuraminic acid) out of the lysosome.

Very diverse presentation:

-        severe forms (ISSD: Infantile Sialic acid Storage Disease) occurring in utero (with fetal ascites  and hydrops fetalis) or at birth with hypotonia, hepatosplenomegaly often associated with ascites, coarse features, bone abnormalities (calcifications,large diaphyses, vertebral anomalies), motor impairment (spastic quadriplegia), nephrotic syndrome, mental retardation (leukodystrophy at MRI) and convulsions; fatal issue in early childhood.

-        moderate form (originally described in Finland under the name of Salla disease): onset in the first year with hypotonia followed with hypertonia with athetosis, ataxia, nystagmus, psychomotor retardation and sometimes coarse features. There is no organomegaly; most patients live into adulthood but with a significant intellectual impairment.

Biological diagnosis relies on the finding of increased urinary excretion and accumulation of free sialic acid in fibroblasts. Treatment is symptomatic

Anesthetic implications:

management of a multi-handicapped child

References : 

• Héron B, Guffon N. 
  Progrès dans les maladies lysosomiales, 
  In Maladies métaboliques héréditaires, coordinateurs : B Cabrol et P de Lonlay. Série Progrès en Pédiatrie. Doin, 2011, p 25-54.

Updated: September 2018