Chromosomal disorders Problems within the structure of the cell nucleus that carries the genetic information. Down syndrome A condition resulting from a chromosomal abnormality most commonly due to the presence of three copies of chromosome 21; most likely to occur with advanced maternal age. Fracture Breakage of a bone. Fundus The part furthest from the opening of an organ. Gamete intrafallopian transfer (GIFT) A procedure for assisting conception, suitable only for women with healthy Fallopian tubes. Gestation The period during which a fertilized egg cell develops into a baby that is ready to be delivered; averages 266 days in humans. Haemolysis The destruction of red blood cells. Haemorrhoid Enlargement of the normal spongy blood-filled cushions in the wall of the anus.