Which are the symptoms of Pallister-Killian Syndrome / Tetrasomy 12p?

Pallister-Killian Syndrome, also known as Tetrasomy 12p, is a rare genetic disorder caused by the presence of extra genetic material on the short arm of chromosome 12. This condition is characterized by a wide range of symptoms that can vary in severity from person to person.

Physical Features:

• Distinctive facial features: individuals with Pallister-Killian Syndrome may have a high forehead, widely spaced eyes, a flat nasal bridge, a small mouth, and a pointed chin.


• Hypotonia: decreased muscle tone, which can lead to poor muscle strength and coordination.


• Abnormal pigmentation: patches of lighter or darker skin may be present, typically in a mosaic pattern.


• Extra nipples or other genital abnormalities may occur.


• Short stature: individuals with this syndrome tend to be shorter than average.


• Skeletal abnormalities: these can include scoliosis (curvature of the spine), joint contractures, and abnormalities of the hands and feet.

Developmental and Intellectual Disabilities:

• Global developmental delay: individuals with Pallister-Killian Syndrome often experience delays in reaching developmental milestones such as sitting, crawling, and walking.


• Intellectual disability: most individuals with this syndrome have some level of intellectual impairment, ranging from mild to severe.


• Speech and language delays: affected individuals may have difficulty with speech production and language comprehension.


• Learning difficulties: individuals with Pallister-Killian Syndrome may struggle with academic skills, such as reading, writing, and math.

Other Symptoms:

• Hearing loss: some individuals may have sensorineural hearing loss, which can range from mild to profound.


• Vision problems: individuals with this syndrome may have refractive errors, strabismus (crossed eyes), or other eye abnormalities.


• Seizures: epilepsy is relatively common in individuals with Pallister-Killian Syndrome.


• Heart defects: certain structural abnormalities of the heart may be present, including ventricular septal defects or atrial septal defects.


• Genitourinary abnormalities: these can include kidney abnormalities, hypospadias (abnormal positioning of the urethral opening in males), or undescended testes.


• Respiratory issues: some individuals may have recurrent respiratory infections or chronic lung disease.

It is important to note that not all individuals with Pallister-Killian Syndrome will exhibit all of these symptoms. The severity and combination of symptoms can vary widely. Additionally, some symptoms may not be apparent at birth and may become more evident as the individual grows older.