Prader-Willi Syndrome - Causes, Symptoms and Treatment

What is Prader-Willi syndrome?

Prader-Willi syndrome also known as chromosome 15 disorder is a very rare genetic disorder of chromosome 15. In this syndrome, 7 genes on the chromosome 15 are missing/deleted or unexpressed on the paternal chromosome. 1 person out of every 15,000 to 16,000 people in the world is born with the genetic disorder named Prader-Willi syndrome.

This syndrome was described by a group of scientists (Andrea Prader, Heinrich Willi, Alexis Labhart, Andrew Ziegler and Guido Fanconi) in 1956. This disease is characterized by abnormality in physical features and mental health of a new born (short physique, obese body, polyphagia, affected muscle tone i.e. hypotonia, smaller hands and feet, hypogonadism - lower level of sex hormones and problems involved with development of sexual organs, constant feeling of hunger along with mental retardation at a certain extent).

What are the signs and symptoms of Prader-Willi syndrome?

Babies born with Prader-Willi syndrome genetic disorder have abnormal physical stature along with an imbalanced mental system. People born with this syndrome are obese and their hands and legs are smaller than normal. They suffer from mental retardation at some extent and have a seriously affected system in the brain, which controls feelings related to hunger. As the system related to the feeling of hunger does not work properly, they constantly feel hungry and keep eating, which leads to obesity due to over-eating (hyperphagia) and weight gain. They also suffer to some extent from problems with ability to lead a logical life; they fail to co-relate two logical things/concepts in life, they also face problems with their learning ability. Sex organs of people suffering from this disorder are generally under-developed due to the lower level of sex hormones (hypogonadism). Due to poor muscle tone, they face problems in sucking.

Following are the signs and symptoms of Prader-Willi syndrome:

• Lethargy
• Problem in respiration
• Excessive sleeping problem
• Improper alignment of eyes with each other (also known as Strabismus)
• Curvature in the spinal column as against the central axis (known as Scoliosis)
• Speech delay
• Improper and imbalanced mental development; leading to poor coordination between different organs and parts of body
• Skin related problems (bruises, lightness of skin, skin picking etc.)
• Delayed motor development
• Improper sexual development

Causes of Prader-Willi Syndrome:

As mentioned earlier, Prader-Willi syndrome is caused due to deletion of the paternal copies of genes region (SNRPN and necdin genes and clusters of SNORNAs - SNORD64, SNORD107, SNORD108, SNORD109, SNORD116 and SNORD115) on chromosome 15. Due to the imprinting, maternal copies of the deleted genes are not introduced and kept silent, only paternal copies are expressed or introduced, leading to deletion of the genes as parental copy also shows deleted genes.

Diagnosis and Treatment:

Prader-Willi syndrome is diagnosed with the help of distinctive physical characteristics and mental behavior/condition of the patient. The symptoms related to this disorder also can help in diagnosis. Genetic testing (DNA-based methylation testing) is one of the techniques used to diagnose Prader-Willi syndrome.

Unfortunately, this syndrome has no cure. However, earlier diagnosis of this disease in a newborn can help in availing treatments that can help lessen and control various effects of the syndrome. Newborns who are pronounced to carry this disorder, once diagnosed with this syndrome, are given necessary medication such as growth hormones injection and treatments such as therapies to improve muscle tone, to reduce obesity, educational therapies and speech related therapies etc. for other conditions associated with this syndrome.