Whats Prada Willis syndrome?
A rare genetic disorder that is lifelong but non-inheritable that results due to defect in affected child’s paternal genes on chromosome 15.
PWS affects both sexes and all races.
PWS was identified these as cluster of clinical features by Swiss physicians A. Prader, H.Willi and A.Lambhart.
How does PWS occur?
A normal child as you know receives one pair of chromosomes from his parents- the pair made of one from mother and second from father .In Prada Willis syndrome, the affected child receives missing/defective genes on the father’s chromosome 15 or two mother’s chromosome 15 to make a pair with father’s chromosome 15 missing.
Thus, PWS is of two types-
- Paternal Chromosome 15 gene deletion (70%)
- Uniparenteral (mother’s) chromosome 15 Disomy (25%)
- Others (5%)
How does defect in chromosome 15 affect the body?
Defect genes or missing paternal chromosome 15 affect’s the child’s hypothalamus and its resulting function which leads to the clinical features of PWS.
What are the clinical features of Prader Willis syndrome?
Few clinical features are observed at birth and some develop in later stages of life as the child grows.
At birth signs observed are:
- Low birth weight and failure to thrive
- Severe muscle hypotonia leading to suckling and respiratory problems
- Delayed motor milestones
- Subtle facial dysmorphia- almond shaped eyes, narrow forehead, triangle shaped mouth
During child’ growing year
- Hyperphagia with slow metabolic rate leading to excessive and rapid weight gain.
- It is most common cause of genetic obesity .Without intervention the child will develop obesity related medical disease and eventual premature death.
- Many factors leads to behavioral and cognitive delays in the child.
- Obesity affects various other systems of the body eventually.As seen the in picture above the child has developed scoliosis.
How is it diagnosed?
By a simple blood genetic testing
PWS like most genetic disorders are managed medically/surgically based on symptom presentations but is not curable. The affected individual is has the disease lifelong.
Growth hormone and sex hormone replacement therapy is FDA approved for use at appropriate age .This replacement therapy helps in child’s body growth and development as the normal functioning of hypothalamus is affected in PWS.