Galactosialidosis. Juvenil type. Combined alpha-neuraminidase and beta-galactosidase deficiency.
Incidence
Autosomal recessive disease. Similar phenotype than Sialidosis II juvenil chronic form. This phenotype appears to have a much higher incidence in Japan but also has been reported in other countries.
Clinical Characteristics
The first manifestation may become apparent as early as the third year of life. This form is a less dramatic neurological syndrome than the others galactosialidosis and sialidosis II. Neurological abnormalities include myoclonic seizures, action myoclonus, myoclonic epilepsy, ataxia, macular cherry red spots and corneal clouding. Neurological deterioration may be very slow and the mental function of half the patient is normal. Angiokeratoma, coarse facial features and skeletal changes are other characteristic features. Very rarely there may be visceromegaly. Patients survive well into adulthood. Thin layer chromatography of the urine demostrates a high concentration of sialyated oligosacharides several hundreds times greater than normal. Electronic microscopy show clear membrane-bound inclusions in biopsy of skin fibroblasts, liver and bone marrow histiocytes. There is a marked deficiency of activity of alpha-neuraminidase and beta-galactosidase in cultured fibroblasts and leukocytes.
Precipitants
no
Provocation Tests
no
Diagnostic Procedures
EB-W, EB-F. There is excretion of sialylated oligosaccharides in urine and a marked deficiency of the activity of alpha-neuraminidase and beta-galactosidase.