Prenatal detection of free sialic acid storage disease: genetic and biochemical studies in nine families

Sialic acid storage disorders, Salla disease (SD) and a severe infantile fo rm of disease (ISSD), are recessively inherited allelic lysosomal storage d isorders due to impaired egress of free sialic acid from lysosomes. Fourtee n pregnancies at risk of adult-type free sialic acid storage disease, SD, w ere monitored by sialic acid assays, genetic linkage or mutation detection analyses using chorionic villus samples. Three affected and 12 unaffected f etuses were identified. The first studies were based on the sialic acid ass ays alone, but the location of the gene enabled the use of genetic linkage analysis and, more recently, the identification of the SLC17A5 gene and dis ease-causing mutations added yet another possibility for prenatal studies. A missense mutation 115C-->T (R39C) is present in 95% of all Finnish SD all eles, providing an easy and reliable means of diagnostic studies. Both mole cular and biochemical (sialic acid assay) studies can be used for prenatal diagnosis of free sialic acid storage diseases. Copyright (C) 2001 John Wil ey & Sons, Ltd.