About PKS

What is Pallister-Killian Syndrome?


Pallister-Killian Mosaic Syndrome or PKS happens randomly. It is a chromosome abnormality when a tetrasomy of the short arm of chromosome 12 (12p) occurs for no known reason. PKS is a unique, diverse syndrome that raises a lot of questions about care, symptoms and conditions.

Individuals affected by PKS often have some or all of the following characteristics:

  • Low muscle tone
  • Hypopigmentation of the skin
  • Cognitive and developmental delays. Although most PKS children have these delays, some children are only mildly affected.
  • Diaphragmatic hernias
  • Seizures
  • Speech delay or absence 
  • Sparse scalp hair at birth
  • Facial features that are common to the syndrome include a high forehead, broad nasal bridge, wide space between the eyes and a high arched palate.
  • Hearing and/or sight impairment

How common is PKS?

It is difficult to estimate the prevalence of PKS since many children will not have been diagnosed and many of those who are diagnosed are not reported in medical literature. It is estimated that there are currently fewer than 500 diagnosed cases of PKS in the world. Recent studies report a birth incidence of 5.1 per million live births.
Diagnosis: PKS can be diagnosed in utero via amniocentesis, although occasionally this has produced a false negative. After birth, chromosome disorders are usually diagnosed by examining DNA from white blood cells. However, children with PKS often appear to have normal chromosomes in their blood cells, so the diagnosis of PKS is usually made from skin cells or cells taken from inside the cheek (buccal mucosa) 


Further information:

One of the most comprehensive overviews of PKS was put together by Unique:

View UNIQUE pamphlet

Below is further information prepared by Dr. Krantz (Pediatrician and Medical geneticist Director of the individualised medical genetics center at the Childrens Hospital of Philadelphia) who has worked with individuals affected by PKS:

Subsequent pregnancies information

Clinical recommendations

Life expectancy