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A study of evoked potentials in the 18q-syndrome which includes the absence of the gene locus for myelin basic
1Department of Medicine, Pennsylvania State University, Milton S. Hershey Medical Center, Hershey.
Abstract:
We report evoked potential findings in a patient with 18q-syndrome (18q22.3----qter). The deletion included the locus for myelin basic protein (MBP). Clinical manifestations were mild intellectual deficit, involuntary movements and ataxia. MRI of the brain showed diffusely abnormal white matter. Visual evoked responses were normal. Central conduction was prolonged on median somatosensory evoked potentials and no central response was seen with posterior tibial somatosensory potentials. Putative congenital deficiency of MBP does not necessarily cause abnormal visual evoked responses.
Insights
This study on 18q-syndrome found that a congenital deficiency in myelin basic protein (MBP) did not affect visual evoked responses, despite neurological symptoms. Central nervous system conduction was impacted in somatosensory pathways.
Area of Science:
- Neuroscience
- Genetics
- Clinical Neurology
Background:
- 18q-syndrome is a chromosomal disorder associated with intellectual deficits and neurological abnormalities.
- The deletion in this patient (18q22.3----qter) encompassed the myelin basic protein (MBP) gene locus.
- Myelin basic protein is crucial for central nervous system myelination.
Observation:
- The patient presented with mild intellectual deficit, involuntary movements, and ataxia.
- Brain MRI revealed diffusely abnormal white matter.
- Visual evoked responses (VERs) were within normal limits.
Findings:
- Median somatosensory evoked potentials (SEPs) showed prolonged central conduction time.
- Posterior tibial somatosensory evoked potentials (SEPs) lacked a central response.
- Despite the MBP gene deletion, VERs were not abnormal, suggesting myelin basic protein is not essential for normal visual pathway function.
Implications:
- Congenital myelin basic protein deficiency may not universally impair all sensory pathways.
- This case highlights the complex relationship between specific genetic deletions, white matter integrity, and evoked potential findings.
- Further research is needed to understand the precise role of MBP in different neural pathways and its clinical relevance in 18q-syndrome.