What is Pallister-Killian syndrome (PKS)?
Pallister-Killian syndrome is a very rare genetic condition with just 150 recorded cases to date. However this figure may actually be higher as individuals with mild symptoms may go undiagnosed.
This rare disease is a multi-system disorder. Its defining features include low muscle tone (hypotonia) in infancy and early childhood, intellectual disability, unique facial features and other features which are usually present at birth.
Syndrome Synonyms:
Isochromosome 12p Syndrome; Pallister-Killian syndrome; Tetrasomy 12p syndrome; Tetrasomy 12p, Mosaic
What gene change causes Pallister-Killian syndrome (PKS)?
The syndrome is caused by the presence of an extra abnormal chromosome, known as isochromosome 12p, meaning a cell may have up to four copies of the small arm of chromosome 12.
The syndrome is not inherited and occurs due to mutations during reproductive cell production in the parents which leads to mosaicism, some cells may have the abnormality, some may not. Most occur due to mutations in the mother’s cells.
Mosaic inheritance occurs very early in the development of a fetus. Essentially it is an error in cell division. The human body is made up of 46 chromosomes, in 23 pairs. Mosaicism occurs when an individual has cells in their body with more or less chromosomes than the usual 46. This can trigger issues that affect different systems and parts of the body.
What are the main symptoms of Pallister-Killian syndrome (PKS)?
Facial and physical characteristics include sparse hair, a high forehead, a broad nasal bridge, widely spaced eyes, low-set ears, rounded cheeks, a cleft or high-arched palate.
Extra fingers or toes, a large big toe, and short arms and legs also characterize the syndrome.
Infants with the syndrome are often born with birth defects, as well as unusual skin coloring in patches of the skin. 30% of individuals will also suffer from serious mobility issues and be unable to walk unassisted.
One of the most serious syndromes associated with the syndrome is extremely low muscle tone, as this can cause breathing and feeding difficulties in infants. 40% of individuals are born with a congenital diaphragm hernia that can cause serious medical complications concerning the internal organs.
Individuals with the syndrome may also experience hearing and vision loss and generally present with limited or zero speech.
Possible clinical traits/features:
Short neck, Stenosis of the external auditory canal, Renal cyst, Renal dysplasia, Webbed neck, Thin vermilion border, Single transverse palmar crease, Sparse eyelashes, Seizure, Postaxial hand polydactyly, Postaxial foot polydactyly, Obesity, Omphalocele, Patent ductus arteriosus, Inguinal hernia, Intellectual disability, profound, Intestinal malrotation, Short nose, Anteverted nares, Muscular hypotonia, Rhizomelia, Long philtrum, Macroglossia, Micrognathia, Mesomelia, Joint hypermobility, Macrotia, Kyphoscoliosis, Cryptorchidism, Decreased body weight, Postnatal microcephaly, Flexion contracture, Coarse facial features, Clinodactyly of the 5th finger, Congenital hip dislocation, Congenital diaphragmatic hernia, Coarctation of aorta, Delayed eruption of teeth, Delayed skeletal maturation, Epicanthus, Everted lower lip vermilion, Downturned corners of mouth, Cognitive impairment, Hearing impairment, Short phalanx of finger, Hypospadias, Hypohidrosis, Hypopigmented streaks, Hypoplastic labia majora, Short toe.
How is it diagnosed?
To find out if someone has a diagnosis of Pallister-Killian syndrome (PKS), it is important to have a consultation and evaluation with a clinical genetic specialist. Specialists may also suggest specific genetic testing or other types of tests to help reach a diagnosis. FDNA’s AI technology can help speed up the diagnostic process by analyzing facial features and other health information.
