Prader-Willi syndrome or PWS syndrome is thought to be one of the most common genetic disorders. Prader-Willi syndrome and Angelman syndrome were the first examples in humans of genomic imprinting in Cytogenetics. Angelman syndrome has an entirely different clinical condition with PWS syndrome. I will explain about the Angelman syndrome in my future post.
What is genomic imprinting? Imprinting is a type of marking process that has a memory. Genomic imprinting is where a segment of DNA is marked or imprinted during gametogenesis. This mark will be retained and recognized throughout the life of the individual. Maternal and paternal inherited alleles will be marked differently and are expressed differently in the offsprings. Therefore, the offspring with the same genetic material will have different appearances. The individual with Prader-Willi syndrome is because the loss of paternally inherited region 15q11 – q13 of chromosome 15. Simple to say, the PWS individual does not inherit the region 15q11 – q13 of chromosome 15 from his/her father but only from mother.
Prader-Willi syndrome is the most common genetic cause of marked obesity in humans according to Cytogenetics. It is a complex disorder with cardinal features of
i) Infantile hypotonia (low muscle tone)
ii) Mild growth retardation
iii) Frequent occurrence of breech presentation (baby enters the birth canal with the buttocks or feet first)
iv) Small hands and feet with gracile and tapering fingers
v) Microcephaly (smaller head)
vi) Almond-shaped eyes
vii) Mental deficiency (average IQ of 65)
viii) Short stature and so on.
From the age of about one and half years onward, hyperphagia becomes a serious problem, leading to gross obesity. Due to hyperphagia and gross obesity, diabetes often sets in during adolescence or later. Epilepsy is found in a minority of cases. Mental development is characterised by moderate to severe retardation with tendency to behaviour disorders, especially reactive to food deprivation. Patients with this syndrome may need specialists for assessment and treatment of their behavioural and learning problems, at the beginning of childhood. Prader-Willi syndrome is present in all races and ethnic groups and most cases are sporadic.
In conclusion, Prader-willi syndrome is a genetic disorder that needs treatment and assessment to overcome the learning problem and obesity problem of the patients. I will write a series of Prader-Willi syndrome in this Cytogenetics and Cancer Research blog in order to give people a clear mind about this syndrome. Stay tuned! 
A very deep topic here.. I’m curious, so can this syndrome be treated and how long it needs?
.-= 2012 Doomsday Predictions´s last blog ..2012 Mayan Doomsday Prophecy DVD =-.
Hi! Happy to see you first time here!:)
This syndrome is a genetic disorder that cannot be cured. We can only reduce the symptoms of this disorder. For example, to prevent the obesity, we need to control the patient’s diet and getting some treatments.
I saw a brilliant documentary on Prader-Willi Syndrome. It really opened up my eyes. You often hear (usually in a comical context) about people who are big because they can’t help it but it was interesting to see it in a serious and informative context. The way they interacted with each other was pretty cool.
My daughter is 13 years old and she has the Chromosome 15 Ring Syndrome. Her height is about 4 ft tall and she is obese at about 120 lbs. Her mental capacity right now is that of a first grader, her temper is really brutal when she does not get her way and she becomes very explosive. She was in genotropic (i think I spelled it right) from 2 to about 7 yrs but saw very little improvement in her growth. We live in Houston and we need help with all of the above. Can you guide us?
Hi Roberto! I am so sorry to hear about your daughter. As this syndrome is a constitutional abnormality, so those symptoms are cannot be prevented. What we can do is to let your daughter to undergo the treatment to reduce the effect of those symptoms. However, it is impossible to get rid of those symptoms.
If possible, i will suggest you to seek for the genetic counselor help. I’m sure the genetic counselor can guide you well.
Hi Kok ..Its such a great article i have ever found on Genetic Disorder That Cause Obesity. I really impressed by the cardinal features you mentioned above. Looking forward for your next post. Do you think any kind of surgery can work in this case..please advice..Thanks Jessica