Screwing up GCS is nothing. The clinical genectist that came in a taught a class told us a story of a PMD who screwed up reading a Huntington's Disease screen. Huntington's Disease is caused when a triplet repeat on chromosome 4 goes past 36 repeats. Now the screens come back with two numbers, one for each chromosome. The poor patient's PMD decided to add the numbers together (it was something like 17 and 23), and told her that she was going to develop Huntington's Disease eventually. Oh course she goes to see the clinical genetists, he takes one look at the test and tells her the good news.