Background: Friedreich’s ataxia is the most common hereditary form of ataxia with an incidence
of 1:50,000. Typical symptoms are ataxia, sensory neuropathy, scoliosis with further
skeletal deformities, and cardiomyopathy. The disease is caused by a homozygote mutation
of the frataxin gene on chromosome 9. A rare differential diagnosis in contrast to
the above mentioned is the CAPOS syndrome with an incidence of 1:1,000,000. This syndrome
shows likewise a progressive cerebellar ataxia, areflexia, progressive atrophy of
the optic nerve, sensory-neural deafness, as well as foot abnormalities. Remarkable
is the aggravation of cerebellar ataxia which can be triggered by infections. The
etiology of this syndrome is not fully understood yet; few affected families show
a mutation in the ATP1A3-gene.
Methods: Three patients with Friedreich’s ataxia are compared with one patient with CAPOS
syndrome focusing on their clinical findings. This should help defining the CAPOS
syndrome as its own clinical entity and put into focus of the clinically working neuropediatrician.
Results: The presented cases are very similar in their clinical findings, though there are
some relevant differences. The infection-triggered deterioration of the ataxia is
a unique feature of CAPOS syndrome.
Conclusion: The early diagnosis of the CAPOS syndrome in contrast to Friedreich’s ataxia is desirable,
especially considering the absent cardiomyopathy in this syndrome. This is possible
due to its clinical features. There should be a genetic tasting to harden the clinical
diagnosis and further understand the etiology of the CAPOS syndrome.
