Chapter 17 - Dentato-rubro-pallido-luysian atrophy

Summary

The dentato-rubro-pallido-luysian atrophy (DRPLA) disorder was predominantly seen in the Japanese population. DRPLA is an autosomal dominant neurodegenerative disorder caused by abnormal repeat expansions within the DRPLA gene located on chromosome 12p13.31. Ataxia, choreoathetosis, and/or myoclonus and mental decline are the cardinal signs. Epileptic seizures usually occur in patients with an earlier onset. Unstable expanded CAG repeats in one allele in the DRPLA gene are responsible for this disorder and the size of the CAG expansion is well correlated with age of onset and severity of the disease. There are characteristic degeneration of both the dentato-rubral and pallido-luysian systems in the brain. Diffferential diagnosis includes all types of progressive myoclonic epilepsies, hereditary ataxia, and Huntington chorea. An autosomal dominant hereditary pattern and anticipation from the paternal side make the diagnosis more likely. However, a definitive diagnosis is based on genetic testing.