WHAT IS AHC?
Alternating Hemiplegia of Childhood or AHC is an extremely rare neurodevelopmental disorder characterised by repeated episodes of weakness or paralysis that may affect one side of the body or the other (hemiplegia) or both sides of the body at once (quadriplegia).
Additional episodic symptoms usually include intermittent abnormal eye movements, episodes of muscle stiffness or posturing (dystonia), and in a substantial percentage of cases, seizures. Delays in attaining developmental milestones (developmental delays), cognitive impairment, persistent issues with balance and the presence of continuous dance-like movements of limbs or facial muscles (chorea) may occur independently of episodes of paralysis, weakness or stiffness and persist between episodes.
The severity of AHC and the specific types of episodes that occur can vary dramatically from one individual to another. First symptoms usually begin before the age of 18 months. AHC is caused by mutations in the ATP1A3 gene in the majority of those affected.