They Human Genome Project is charging along, estimated by the year 2005 every gene will be mapped. Right now we are sitting, not quite halfway through the project and about 50 thousand genes have been mapped. We ll talk specifically about chromosome abnormalities first. You can again see children or adults who have developmental disorders either due to a change in the number of chromosomes or certain structural rearrangements. In humans we can see whole chromosome changes.
Polyploidy is very unusual.
More of an obstetrical sort of a problem - by polyploidy we mean that you have a whole extra set of chromosomes. So an individual with 69 chromosomes and those sort of things. Because of phenomena like imprinting there s a difference between if that whole extra set came from the sperm or the egg, but by and large it presents either with pregnancy loss, or with a molar pregnancy. Again, a whole extra set of chromosomes is not typically going to direct development in the way that you d expect it to. So from a practical standpoint medically, at least in humans with birth defects or developmental anomalies, trisomy s and monosomy s are the major chromosome abnormalities.