Abstract
Mutations in the potassium channel-related gene KCTD7 were described so far in a single family with progressive myoclonus epilepsy. We describe a unique phenotype: acute onset of myoclonus and ataxia, associated with abnormal opsoclonus-like eye movements; improvement of clinical symptoms under steroid treatment; and appearance of epileptic activity on EEG 2 years later without overt seizures. After excluding possible genetic causes, whole-genome exome sequencing was performed in order to identify the causative gene. One heterozygous missense mutation (R84W) was detected by exome sequencing and a large heterozygous deletion of exons 3 and 4 by MLPA analysis. The father is heterozygous for the R84W mutation and the mother is heterozygous for the exon 3+4 deletion. The mutation affects a highly conserved segment of the predicted protein, changing a basic amino acid into neutral. The large deletion probably results in a truncated protein. The different phenotype broadens the spectrum of KCTD7-related diseases. Therefore, patients diagnosed as having opsoclonus-myoclonus with an atypical course should be evaluated for KCTD7 mutations.
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Acknowledgments
We thank Prof. Pranzatelli MR from the National Pediatric Myoclonus Center, Southern Illinois University School of Medicine for his great help in the evaluation and treatment of our patient.
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Blumkin, L., Kivity, S., Lev, D. et al. A compound heterozygous missense mutation and a large deletion in the KCTD7 gene presenting as an opsoclonus-myoclonus ataxia-like syndrome. J Neurol 259, 2590–2598 (2012). https://doi.org/10.1007/s00415-012-6545-z
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DOI: https://doi.org/10.1007/s00415-012-6545-z