Sialidosis type II (Mucolipidosis I). Early infantile form. Alpha-neuraminidase deficiency.
Incidence
Autosomal recessive disease.
Clinical Characteristics
These patients resemble infantile GM1 gangliosidosis. In this form, hepatosplenomegaly and ascitis may be present in the neonate or develop after a few weeks. Dysmorphic features such as puffy faces, depressed nasal bridge and gingival hyperplasia are noted early. Hepatomegaly may be present. Macular cherry red spots is a major sign. Punctate lens opacity and deafness may occur. Neurologic development is severely impaired. Psychomotor retardation is severe. X-rays disclose periosteal thickening of the long bones, stippling of the epiphyses and ovoid vertebral bodies. Foam cells in bone marrow smears and clear vacuoles in peripheral lymphocytes can be seen. There may be evidence of peripheral neuropathy. The course of the disease is severe and usually leads to death after a few months or in the second year of life. Some children live longer with severe mental impairment, intention myoclonus, seizures and motor difficulties. In these cases, there is mild deficiency of alpha-neuraminidase. Some patients develop severe renal dysfunction with proteinuria in the first year of life (nephrosialidosis). They may develop fine corneal opacities. Survival is for several years.
Precipitants
no
Provocation Tests
no
Diagnostic Procedures
EB-W, EB-F. Foam cells in bone marrow smears and clear vacuoles in peripheral lymphocytes can be seen. There is excretion of sialylated oligosaccharides in urine and a marked deficiency of the activity of alpha-neuraminidase.