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Morphological observations in the nervous system of prenatal mucopolysaccharidosis II (M. Hunter)
Abstract:
Light and electron microscopic finding in the nervous system of a 23-week-old fetus are reported, in which MPS II was diagnosed prenatally. The degrees of myelination and neuronal differentiation were similar as in a normal fetus of the same age. A storage of mucopolysaccharides in typical vacuolar inclusion bodies was present throughout the peripheral and central nervous system, mainly in cells of mesenchymal origin. "Zebra" bodies and granulo-membranous bodies, which are thought to represent secondard ganglioside accumulation were only found in the well developed neurons of the spinal cord and spinal ganglia, but not in the poorly developed neurons of the cerebellar and cerebral cortex. Mucopolysaccharide storage in endothelial cells of cerebral bood vessels precedes the appearance of lipid storgae in cerebral neurons.
Insights
Prenatal diagnosis of Mucopolysaccharidosis type II (MPS II) in a fetus revealed normal neural development but widespread mucopolysaccharide storage. Lipid accumulation occurred in mature neurons, suggesting a specific progression of cellular damage in this rare genetic disorder.
Area of Science:
- Neuropathology
- Developmental Biology
- Genetics
Background:
- Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a rare X-linked genetic disorder.
- It results from deficient iduronate-2-sulfatase enzyme activity, leading to the accumulation of glycosaminoglycans in various tissues.
- Prenatal diagnosis allows for early intervention and management strategies.
Purpose of the Study:
- To investigate the neuropathological findings in a fetus diagnosed with MPS II prenatally.
- To characterize the distribution and type of cellular storage in the developing nervous system.
- To correlate the observed storage with neuronal differentiation and myelination status.
Main Methods:
- Light and electron microscopy were utilized to examine nervous system tissues.
- Fetal tissues were analyzed for the presence of mucopolysaccharide and lipid storage bodies.
- Comparison was made with a normal fetus of the same gestational age.
Main Results:
- The fetus showed normal myelination and neuronal differentiation comparable to a 23-week-old normal fetus.
- Widespread mucopolysaccharide storage was observed in vacuolar inclusion bodies, primarily in mesenchymal cells throughout the central and peripheral nervous systems.
- "Zebra" bodies and granulo-membranous bodies, indicative of ganglioside accumulation, were present only in well-developed neurons (spinal cord and ganglia), not in immature cortical neurons.
- Mucopolysaccharide storage in cerebral blood vessel endothelial cells preceded lipid storage in cerebral neurons.
Conclusions:
- Despite normal neural development, prenatal MPS II diagnosis revealed significant cellular storage of mucopolysaccharides in the fetal nervous system.
- The pattern of storage suggests a specific progression, with endothelial storage preceding neuronal lipid accumulation.
- These findings highlight the utility of prenatal diagnosis for understanding the early neuropathological impact of MPS II.