Homozygosity for an allele carrying intermediate CAG repeats in the dentatorubral-pallidoluysian atrophy (DRPLA) gene results in spastic paraplegia.

We report a family with autosomal recessive spastic paraplegia. Patient 1 was a 37-year-old woman and patient 2 was her 35-year-old sister. They showed spastic paraplegia with mild truncal ataxia and dysarthria but no dementia, epilepsy, myoclonus, or other involuntary movements. They were the products of a consanguineous marriage but the parents were neurologically normal. We analyzed the CAG repeats of the dentatorubral-pallidoluysian atrophy (DRPLA) gene in the family members. The patients were homozygous for an allele carrying an intermediate size of CAG repeats (41 or 40 repeats) in the DRPLA gene; the parents were heterozygous for an intermediate allele and a normal allele in this gene. Homozygosity for an intermediate allele in the DRPLA gene appears to have resulted in spastic paraplegia different from any DRPLA phenotype.