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A Japanese case of infantile sialic acid storage disease
C Nakano1, Y Hirabayashi, K Ohno
1Department of Pediatrics, National Sanatorium, Suzuka Hospital, Mie, Japan.
Insights
This study details a rare genetic disorder, infantile sialic acid storage disease (ISAD), in a Japanese child. ISAD is characterized by severe developmental delays and neurological issues due to abnormal sialic acid accumulation.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Background:
- Infantile sialic acid storage disease (ISAD) is a rare lysosomal storage disorder.
- It is characterized by the accumulation of free sialic acid within cells.
Observation:
- A 4-year-old Japanese girl presented with failure to thrive, distinctive facial features, enlarged liver and spleen, severe intellectual disability, and spastic quadriplegia.
- Electron microscopy of skin fibroblasts showed distended lysosomes, indicative of a lysosomal storage disorder.
- Elevated free sialic acid levels were detected in urine and cultured fibroblasts.
Findings:
- Despite lysosomal abnormalities and high free sialic acid, lysosomal enzyme activities were normal.
- Brain MRI revealed atrophy, diffuse white matter hyperintensities, and basal ganglia hypointensities on T2-weighted images.
- This is the first reported case of ISAD in a non-Caucasian family.
Implications:
- This case expands the known ethnic diversity of infantile sialic acid storage disease.
- Further research into the specific genetic mutations and biochemical pathways of ISAD is warranted.
- Early diagnosis and understanding of ISAD are crucial for potential therapeutic interventions.
Abstract:
We report a 4-year-old Japanese girl with infantile sialic acid storage disease. She presented with failure to thrive, coarse facial features, hepatosplenomegaly, severe mental retardation and spastic quadriplegia. Electron microscopic examination of cultured skin fibroblasts revealed multiple vacuoles and inclusion material representing distended lysosomes, thus suggesting a lysosomal storage disorder. A high concentration of free sialic acid was present in the urine and cultured fibroblasts, but bound sialic acid was not increased. The activity of a variety of lysosomal enzymes was not diminished. The MRI findings included brain atrophy and a diffuse high signal in the cerebral white matter and low signal in the basal ganglia on T2-weighted images. To our knowledge, this is the first case of infantile sialic acid storage disease described in a non-Caucasian family.