22q13, or the Phelan-McDermid syndrome, is a deletion syndrome that results in a lag in developmental behavior. My cousin has this deletion. It is a new deletion that has only been found due to a advancement in technology, particularly Fluorescence in situ hybridization (FISH). Until now it has been diagnosed as basic autism seeing as individuals who have this deletion suffer from a lack of eye contact and some social communication deficiencies. However other symptoms such as habitual chewing and certain body and facial features have allowed doctors to be able to diagnose more and more individuals correctly, but many still require multiple DNA inspections in order to find the problem.
Most of these things I already knew. What I did not know is that many of the 22q13 deletion patients suffer from lack of perspiration and that, for some reason, these children are prone to ear infections. I also did not know (seeing as my cousin Kit is the only person I know with 22q13) that many of Kit's features are a result of this deletion. For example, his gorgeously-long eyelashes and large hands. I also did not know that there is varying degrees. I figured that with a deletion of a chromosome, the individuals would express the same basic symptoms at about the same levels. However, this is not true and some are much more advanced and communicate more than others.
Lots of research still needs to be done to determine the cause, whether genetic or environmental, and perhaps ways to implement early developmental programs to encourage an increase in communication and coordination. It is known, though, that a unbalanced translocation on the 22 genes or the parents lead to an increased chance of 22q13 developing in their children.