International AHC Day, also known as AHC Awareness Day, is observed worldwide every January 18 to educate the public about Alternating Hemiplegia of Childhood (AHC), a rare neurological disorder. The day commemorates the landmark discovery made on January 18, 2012, which revealed that approximately 70-80% of AHC cases are linked to a mutation in the ATP1A3 gene. Patients with AHC experience transient episodes of hemiplegia, which can vary in severity and duration, alongside a range of neurological symptoms. The condition is complex and difficult to diagnose, often leading to misdiagnosis as epilepsy. Organizations such as the Spanish Association of Alternating Hemiplegia of Childhood (AESHA) and Alternating Hemiplegia of Childhood UK (AHC UK) support the observance, emphasizing the need for further research into the condition, especially since about 20% of patients do not have the known genetic mutation.