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[Neurophysiological studies on group A xeroderma pigmentosum in early childhood]
Y Iwakawa1, M Shimohira, S Kondo
1Department of Pediatrics, Tokyo Medical and Dental University.
Insights
Xeroderma pigmentosum (XP) patients show abnormal sleep patterns and early neurological signs, suggesting basal ganglia involvement due to potential DNA damage from endogenous compounds. This highlights early CNS degeneration in XP.
Area of Science:
- Neuroscience
- Genetics
- Sleep Medicine
Context:
- Xeroderma pigmentosum (XP) is a rare genetic disorder characterized by defective DNA repair.
- Early childhood neurophysiological assessments are crucial for understanding XP's neurological impact.
- Previous studies have not extensively detailed sleep abnormalities in pediatric XP patients.
Purpose:
- To investigate neurophysiological and sleep abnormalities in young children with Xeroderma pigmentosum (XP).
- To explore potential early central nervous system (CNS) degenerative changes in XP.
- To correlate DNA repair defects with neurological manifestations in XP.
Summary:
- Neurophysiological tests (EEG, ABR, NCV) were normal in 8 pediatric XP patients.
- Polysomnography revealed abnormal sleep parameters, including altered REM sleep and body movement patterns.
- Neurological examinations showed hypotonia, delayed motor skills, speech delay, and diminished reflexes, indicating early CNS deficits.
Impact:
- Findings suggest that endogenous compounds may cause DNA damage in the nervous system, leading to neurodegeneration in XP.
- The basal ganglia may be an early site of CNS degeneration in XP, potentially linked to dopaminergic system dysfunction.
- This research opens avenues for understanding the interplay between DNA repair, sleep, and neurological health in XP.
Abstract:
Neurophysiological studies were performed on 8 patients with group A xeroderma pigmentosum during early childhood. EEG, ABR and NCV were normal during this period. In contrast, various sleep parameters detected by polysomnography showed abnormal findings even in the neurologically normal patient. Decreased % sleep REM was seen in a case, and decreased frequency of REMs were seen in another. Body movements were extremely high or low in frequency in 3 cases in whole night sleep. The distribution of body movements were abnormal; in control subjects, the frequency was higher in SREM and stage 1 than in slow wave sleep; in 7 cases, it was higher in slow wave sleep than in stage 1 or 2, or body movements were extremely frequent. Neurological examination revealed soft signs in various systems in early childhood. All cases except one showed hypotonia. Many cases were slow in learning to walk and the gait was unstable. Speech delay and decreased deep tendon reflexes, especially of patella, were seen in most cases. Since the neural deficits in XP may be related to the DNA repair defect, these findings indicate the possibility that some endogenous compounds distributing all over the nervous system might produce the DNA damages. Because the body movements during sleep are controlled by the nigrostriatal dopaminergic system, present data indicate that the basal ganglia might be one of the earliest degenerative systems in the CNS. Recently, some studies have suggested the possibility that oxygen radical mechanisms might be involved in the development of the dopamine neurodegenerative process in Parkinson's disease.(ABSTRACT TRUNCATED AT 250 WORDS)