THE SPECTRUM OF FREE NEURAMINIC ACID STORAGE DISEASE IN CHILDHOOD - CLINICAL, MORPHOLOGICAL AND BIOCHEMICAL OBSERVATIONS IN 3 NON-FINNISH PATIENTS

N-acetylneuraminic acid (sialic acid) storage disease is a rare autoso mal recessive lysosomal disorder. Clinically two major forms exist, an infantile type with severe progression leading to early death, and a milder form (Salla disease) with a protracted course, Intermediate for ms may also exist. Diagnosis rests on the determination of an excessiv e excretion of sialic acid in urine and concomitant storage in fibrobl asts, the severe forms exhibiting the highest excretion and storage, W e present clinical, morphological, and biochemical data on three non-F innish patients with sialic acid storage disease. Patient 1 was a pret erm infant with neonatal ascites, coarse face, hepatosplenomegaly, pal e skin, and wispy hair. Vacuolated lymphocytes were abundant in a peri pheral blood smear and he excreted large amounts of free sialic acid. High levels of free sialic acid were also found in cultured skin fibro blasts. He died at age 6 months from progressive respiratory insuffici ency, Patient 2 was an 11-month-old Egyptian girl with coarse face, fr equent upper respiratory tract infections, hepatosplenomegaly, and sev ere psychomotor retardation, Sialic acid excretion was elevated, likew ise the storage in fibroblasts. Histological investigations documented vacuolar storage in a skin biopsy and in iliac crest tissue, Patient 3 was a 16-year-old girl with slightly coarse face, severe generalized muscular hypotonia, ataxia, and kyphoscoliosis originally diagnosed a s having postpartum asphyxia. She suffered progressive motor function loss and had dysarthria, Urinary sialic acid was elevated and a skin b iopsy demonstrated vacuolization. The clinical variability of sialic a cid storage disease is exemplified by these three cases, Simple urinar y screening for free sialic acid facilitates the diagnosis, The degree of urinary excretion may indeed correlate with clinical presentation and progression. (C) 1996 Wiley-Liss, Inc.