SYT1 (Synaptotagmin 1) is an important gene which controls communication between nerve cells in the brain. So far, around twenty individuals around the world have been diagnosed with an alteration in the SYT1 gene (SYT1 mutation). SYT1 mutations occur by chance and are not inherited from either parent (de novo). We are at an early stage of understanding how SYT1 mutations affect brain development to cause the wide range of problems experienced by patients and their families.