EFHC1 (EF-hand domain containing 1) is a microtubule-associated protein with critical roles in neuronal development and cilia function. As a microtubule inner protein component of dynein-decorated doublet microtubules in cilia axoneme, EFHC1 is required for motile cilia beating 1. During cortical development, EFHC1 regulates cell division and neuronal migration by controlling microtubule dynamics 23. Loss of EFHC1 function disrupts mitotic spindle organization, impairs M-phase progression, and induces microtubule bundling, leading to radial migration defects in cortical progenitors 2. EFHC1 also negatively regulates neurite growth by fine-tuning microtubule cytoskeleton dynamics 4. Functionally, EFHC1 may enhance calcium influx through CACNA1E and stimulate programmed cell death 2. EFHC1 mutations are associated with juvenile myoclonic epilepsy (JME) and juvenile absence epilepsy, with pathogenic variants identified across diverse populations 53. However, population-specific genetic backgrounds influence penetrance, as some reportedly pathogenic mutations occur in healthy individuals, particularly in African and Hispanic populations 67. Recent reassessment suggests EFHC1 testing currently lacks sufficient scientific foundation for routine clinical diagnosis and should remain research-focused 7.