Santavuori disease: diagnosis by leukocyte ultrastructure.
Since Santavuori's 1973 description of infantile neuronal ceroid lipofuscinosis, 46 of the 58 reported cases have been Finnish. We recognized the disorder in three children from two different American families by leukocyte ultrastructure and clinical picture. These patients had the cardinal features of early developmental deterioration, retinal blindness, microcephaly, and seizures. Ultrastructural study of buffy coats revealed compact, granular, osmiophilic membrane-bound cytoplasmic inclusions in approximately 15 to 21% of lymphocytes and larger mononuclear cells. Similar cytoplasmic inclusions were seen in neurons, astrocytes, macrophages, and endothelial cells of a frontal lobe biopsy from one patient. The use of leukocyte ultrastructure combined with an awareness of the characteristic clinical picture should lead to the increased recognition of this disorder in American children.