Prader-Willi syndrome (PWS)

What is Prader-Willi syndrome (PWS)

Prader-Willi syndrome is a genetic disorder that is currently the most common cause of life-threatening childhood obesity. In childhood, individuals with the condition develop an insatiable appetite that triggers chronic overeating.

The syndrome occurs in 1 in 15,000 live births.

Syndrome Synonyms:
Prader-Labhart-Willi Syndrome, PWS

What gene change causes Prader-Willi syndrome (PWS)?

In 70% of cases, a deletion on the paternal copy of a specific region of chromosome 15 in each cell causes the syndrome. 25% of cases are caused by the duplication this specific region of chromosome 15 from the mother. The remainder of cases are caused by a translocation between both chromosomes 15 and subsequent deletion of the specific region. The condition is most often the result of a random mutation or event.

Microdeletion inheritance occurs when there is a deletion of several genes on a chromosome. The specific chromosome on which the deletions occur will determine the syndrome they cause.

Normally we inherit one copy of each chromosome pair from each biological parent. In the case of disomy, both copies of the chromosome pair are received from one parent and none from the other. This is also often known as uniparental disomy. With most genes this is not an issue, and will not cause any medical or health issues. However when specific genes are concerned, issues with genomic imprinting, can cause specific genetic syndromes.

What are the main symptoms of Prader-Willi syndrome (PWS)?

The main symptoms of Prader-Willi syndrome in infancy are hypotonia (low muscle tone), failure to thrive, and feeding difficulties. In childhood, these symptoms are replaced with an insatiable appetite, chronic overeating, obesity, and often the development of diabetes type 2.

Typical facial characteristics of the syndrome include a narrow forehead, almond-shaped eyes, and a triangular mouth. Short stature and small hands and feet are also common physical characteristics.

Other symptoms include underdeveloped genitals in both males and females and delayed or incomplete puberty that often results in infertility. Mild-moderate intellectual disability is common, as are issues with compulsive disorders and problem behavior related to a lack of impulse control.

Possible clinical traits/features:
Delayed speech and language development, Hypoventilation, Generalized hypotonia, Generalized hypopigmentation, Frontal upsweep of hair, Hypopigmentation of the skin, Hypopigmentation of hair, Hypogonadotropic hypogonadism, Hypoplastic labia minora, Short foot, Adrenal insufficiency, Hip dysplasia, Short stature, Global developmental delay, Growth hormone deficiency, Polyphagia, Hyperinsulinemia, Nasal speech, Hypermetropia, Kyphosis, Osteoporosis, Oligomenorrhea, Obesity, Primary amenorrhea, Precocious puberty, Psychosis, Syndactyly, Seizure, Cutaneous photosensitivity, Poor gross motor coordination, Poor fine motor coordination, Poor suck, Scrotal hypoplasia, Esotropia, Clitoral hypoplasia, Dolichocephaly, Ventriculomegaly, Motor delay, Delayed puberty, Impaired pain sensation, Decreased muscle mass, Failure to thrive in infancy, Cryptorchidism, Decreased fetal movement, Downturned corners of mouth, Infertility, Micropenis, Osteopenia, Intellectual disability, Myopia, Narrow nasal bridge, Narrow palm.

How is Prader-Willi syndrome (PWS) diagnosed?

To find out if someone has a diagnosis of Prader-Willi syndrome (PWS), 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.