Phenotypic spectrum of Salla disease, a free sialic acid storage disorder.
Salla disease (MIM 269920) represents the mildest phenotype among recessively inherited lysosomal-free sialic acid storage disorders. Although the vast majority of Salla disease patients in Finland share the same founder mutation, R39C in the SLC17A5 gene, there still is a wide clinical variation among mentally retarded, ataxic patients. We evaluated neurologic and neurocognitive findings of Salla disease in a cross-sectional study of 41 Finnish patients who were 11 months to 63 years of age (median = 19.5 years). The phenotype of Salla disease could be classified into two main categories. The majority of patients (90%) had so-called conventional phenotype, including a subgroup of seven patients with relatively mild symptoms. All but two patients with conventional phenotype were homozygous for the Finnish founder mutation. Four severely disabled, profoundly mentally retarded patients, 15-28 years of age, clearly could be clinically delineated as a separate group, likely reflecting the underlying compound heterozygous genotype. A typical developmental pattern could be outlined in the conventional type of the disease, emphasizing a strong motor handicap in Salla disease. The cognitive profile consisted of better verbal ability, especially speech comprehension, compared with nonverbal functioning in all patients. Our results indicate a partial genotype-phenotype correlation, although factors other than the molecular background are also involved in the phenotypic manifestation of Salla disease.
Varho
Tarja T
TT
Department of Medical Genetics, University of Turku, Finland.
Alajoki
Liisa E
LE
Posti
Kristiina M
KM
Korhonen
Tapio T
TT
Renlund
Martin G
MG
Nyman
Samuel R G
SR
Sillanpää
Matti L
ML
Aula
Pertti P
PP
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D019158:N-Acetylneuraminic Acid / Q000235:genetics / Q000378:metabolism / Q000652:urine*; D010641:Phenotype; D029461:Sialic Acid Storage Disease / Q000235:genetics* / Q000503:physiopathology / Q000523:psychology / Q000652:urine*; D018709:Statistics, Nonparametric
D019158:N-Acetylneuraminic Acid