<s>[INST] <<SYS>> This is a medical question of type : inheritance <</SYS>> Is isodicentric chromosome 15 syndrome inherited ? [/INST] Isodicentric chromosome 15 syndrome is usually not inherited. The chromosomal change that causes the disorder typically occurs as a random event during the formation of reproductive cells (eggs or sperm) in a parent of the affected individual. Most affected individuals have no history of the disorder in their family. </s>