PKS happens randomly and for no known reason. It is thought that there are under 200 diagnosed cases of PKS in the world, however doctors at Children's Hospital in Philadelphia believe that the incidence of PKS is much higher! They feel there may be as many as 2,000 cases in the United States alone. So why aren't these numbers reflected? It is likely that there may be this many cases, but they are going undiagnosed. A main cause for these undiagnosed cases is the method of testing. PKS can be diagnosed in utero via amniocentesis, although occasionally, even this has produced a false negative. After birth, diagnosis is best made by a buccal smear (although a skin biopsy can be as accurate). The blood cells in the body quickly regenerate and the mosaic cells leave the bloodstream after just a few days, making a diagnosis via bloodwork inconclusive or falsely negative. Ask for a buccal smear if you have any reason to believe your child may have the traits of a syndrome.

The above graph was developed with information provided by PKS Support, an online Yahoo support group.