They arise from the rapid development of genetic testing which promises to identify more indelible elements of human differentiation upon which adverse discrimination could be based. Pregnant women in many countries have for years been able to undergo amniocentesis to detect the presence in the foetus of genetic abnormalities such as Down Syndrome. But the progress made over the past decade in the Human Genome Project will ultimately ensure that genetic causes of human differences are identified. Many that are responsible for inherited cancers and other serious diseases have already been isolated. Amongst those discovered are the genes causing several late onset disorders such as cystic fibrosis, muscular distrophy, Huntington's Disease and, most widespread of all, Alzheimer's Disease.
Mistakes can occur in the performance of tests to identify the presence of genetic disorders.
As with the well known tests for HIV, there can be false positives and false negatives. But apart from this problem, current tests cannot predict, with accuracy, precisely when a genetic condition will manifest itself. But there is enormous variation in the age of onset and in the range of symptoms that will appear in a given individual. In the past, family members would often know generally about inherited conditions which might manifest themselves in succeeding generations. Now there is the potential to remove the uncertainty and to diagnose with near perfect accuracy the presence of the gene which, in due course, will manifest itself and, in some conditions, lead on to profound disabilities or certain death.