Answer:
Genetic disorder.
Abnormal cell division.
Step-by-step explanation:
Down's syndrome is a genetic disorder condition which is caused by the abnormal cell division during the development of the sperm cell or the egg cell. Due to abnormal cell division, the patient receives and extra copy of chromosome which is the cause of Down's syndrome. This is a genetic disorder which means that this disease occur during the formation of baby when the sperm and egg cells fuse together so this abnormal cell division occur in the sperm or egg cell of the patient's parent.