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Santavuori disease: diagnosis by leukocyte ultrastructure
Insights
Infantile neuronal ceroid lipofuscinosis, a rare genetic disorder, was identified in American children using leukocyte ultrastructure and clinical signs. This method aids in recognizing the condition beyond its typical Finnish prevalence.
Area of Science:
- Neurology
- Genetics
- Cell Biology
Background:
- Infantile neuronal ceroid lipofuscinosis (INCL) is a rare lysosomal storage disease.
- Most reported cases have been of Finnish origin since Santavuori's initial description in 1973.
Observation:
- The study identified INCL in three children from two American families.
- Patients presented with developmental deterioration, blindness, microcephaly, and seizures.
- Ultrastructural analysis of buffy coats revealed characteristic cytoplasmic inclusions in lymphocytes and mononuclear cells.
Findings:
- Osmiophilic, membrane-bound cytoplasmic inclusions were observed in 15-21% of leukocytes.
- Similar inclusions were found in neurons, astrocytes, macrophages, and endothelial cells from a brain biopsy.
- Leukocyte ultrastructure proved a valuable diagnostic marker.
Implications:
- This study expands the known geographic distribution of INCL.
- Utilizing leukocyte ultrastructure can improve early diagnosis of INCL in non-Finnish populations.
- Increased recognition of INCL in American children is anticipated.
Abstract:
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.