Trisomy 18

A condition in which there are three homologous chromosomes per cell in chromosome 18 rather than two which causes severe deformity and intellectual disabilities. These children usually do not survive beyond the first year of life. The condition is characterized by prominent occiput (back part of the skull), overlapping of index finger over third finger, frequent facial abnormalities, straight nose coming off sharply from the forehead, low set ears and cleft palate and lip.