Fig. 9From: Calcium channelopathies and intellectual disability: a systematic reviewThe mechanism of how gain-of-function variants can lead to ID/GDD. Calcium ions can enter into neuronal cell via Cav1.2, Cav1.4, Cavα2δ, Cav2.1, Cav2.2, Cav2.3, Cav3.1, Cav3.2 and Cav3.3. In normal physiology, some of the calcium ions go to the nucleus to initiate gene transcription, translation and protein synthesis essential for learning and memory, some go to mitochondria for ATP synthesis (essential for learning and memory) and some to the endoplasmic reticulum (ER) for storage. Gain-of- function variants can allow excessive influx of calcium ions inside the cells. This will reduce the amount of ATP production while contributing to the accumulation of reactive oxygen species (ROS) and release of cytochrome C that induces apoptosis of neuronal cell. Many red and blue solid circles stand for high calcium levelsBack to article page