Corpus callosum agenesis-neuronopathy syndrome

Corpus callosum agenesis-neuronopathy syndrome, also known as Charlevoix disease or Andermann syndrome, is a rare autosomal recessive neurological disorder characterized by agenesis (absence) or hypoplasia (underdevelopment) of the corpus callosum combined with a progressive sensorimotor neuropathy. The condition was first described in the Charlevoix and Saguenay-Lac-Saint-Jean regions of Quebec, Canada, where it occurs with higher frequency due to a founder effect. It is caused by mutations in the SLC12A6 gene (also known as KCC3), which encodes a potassium-chloride cotransporter important for neuronal function and development. The syndrome primarily affects the central and peripheral nervous systems. Key clinical features include intellectual disability (typically moderate to severe), progressive peripheral neuropathy leading to muscle weakness and wasting (particularly in the limbs), hypotonia, areflexia, and delayed motor milestones. Many affected individuals never achieve independent ambulation or lose the ability to walk during childhood or adolescence. Facial features may include a long face, high-arched palate, and widely spaced eyes. Seizures, scoliosis, and contractures may also develop. Brain imaging reveals partial or complete agenesis of the corpus callosum. There is currently no cure or disease-modifying treatment for Andermann syndrome. Management is supportive and multidisciplinary, focusing on physical therapy, occupational therapy, orthopedic interventions for scoliosis and contractures, seizure management with anticonvulsant medications when needed, and educational support. The prognosis is generally poor, with progressive neurological decline. Many patients have a shortened lifespan, with survival into the third or fourth decade of life, though this varies among individuals.

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