Other Names for this Disease
- Ataxia, chorea, seizures, and dementia
- Dentatorubropallidoluysian atrophy
- Haw River syndrome
- Myoclonic epilepsy with choreoathetosis
What are the signs and symptoms of dentatorubral-pallidoluysian atrophy (DRPLA)?
What causes dentatorubral-pallidoluysian atrophy (DRPLA)?
How is dentatorubral-pallidoluysian atrophy (DRPLA) inherited?
How might dentatorubral-pallidoluysian atrophy (DRPLA) be treated?
When DRPLA appears before age 20, it most often involves episodes of involuntary muscle jerking or twitching (myoclonus); seizures; behavioral changes; intellectual disability; and problems with balance and coordination (ataxia). Epileptic seizures occur in all individuals with onset before 20 years of age.
When DRPLA begins after age 20, the most frequent signs and symptoms are ataxia; uncontrollable movements of the limbs (choreoathetosis); psychiatric symptoms such as delusions; and deterioration of intellectual function (dementia). Seizures are less frequent in individuals with onset between the ages of 20 and 40. Seizures are rare in individuals with onset after age 40.
Individuals who have inherited the condition from an affected parent typically have symptoms 26 to 29 years earlier than affected fathers, and 14 to 15 years earlier than affected mothers.
DRPLA is caused by a mutation in the ATN1 gene. This gene provides instructions for making a protein called atrophin 1. Although the function of atrophin 1 is unclear, it likely plays an important role in nerve cells (neurons) in many areas of the brain.
The ATN1 mutation that causes DRPLA involves a DNA segment known as a CAG trinucleotide repeat. This segment is made up of a series of three DNA building blocks (cytosine, adenine, and guanine) that appear multiple times in a row on the gene. Normally, this CAG segment is repeated 6 to 35 times within the ATN1 gene. In people with DRPLA, the CAG segment is repeated at least 48 times (and sometimes much more). The abnormally long CAG trinucleotide repeat changes the structure of the atrophin 1 protein, which then accumulates in neurons and interferes with normal cell functions. The dysfunction and eventual death of these neurons lead to the signs and symptoms associated with DRPLA.
DRPLA is inherited in an autosomal dominant pattern, which means that one copy of the mutated gene in each cell is sufficient to cause the disorder. The condition may be inherited from an affected parent or may occur for the first time in the affected individual. In most cases, an affected person has one parent with the condition.
The CAG trinucleotide repeat in the ATN1 gene often increases in size (resulting in a greater number of repeats) when the mutated gene is transmitted from a parent to a child. This "instability" during transmission of the gene results in a phenomenon called anticipation. This means that larger repeat expansions in subsequent generations are usually associated with an earlier onset of the condition and more severe signs and symptoms. Anticipation seen in DRPLA tends to be more prominent when the ATN1 gene is inherited from a person's father (paternal inheritance) than when it is inherited from a person's mother (maternal inheritance). Affected offspring typically have symptoms 26 to 29 years earlier than affected fathers and 14 to 15 years earlier than affected mothers.
- Treatment of seizures with anti-epileptic drugs
- Treatment of psychiatric problems with appropriate psychotropic medications
- Adaptation of environment and care to the level of dementia
- Adaptation of educational programs for affected children.
- Dentatorubral-pallidoluysian atrophy. Genetics Home Reference (GHR). 2008; http://ghr.nlm.nih.gov/condition=dentatorubralpallidoluysianatrophy. Accessed 5/10/2010.
- Brice A. Dentatorubral pallidoluysian atrophy. Orphanet. 2004; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=101. Accessed 5/10/2010.
- Shoji Tsuji. DRPLA. GeneReviews. June 1, 2010; http://www.ncbi.nlm.nih.gov/books/NBK1491/. Accessed 9/5/2012.