Prader Willi Syndrome
Prader Willi syndrome (PWS) is a rare genetic disorder in which seven genes (or some subset thereof) on chromosome 15 (q 11-13) are deleted or unexpressed (chromosome 15q partial deletion) on the paternal chromosome. It was first described in 1956 by Andrea Prader, Heinrich Willi, Alexis Labhart, Andrew Ziegler, and Guido Fanconi of Switzerland.
The incidence of PWS is between 1 in 10,000 and 1 in 25,000 live births. The paternal gene origin is lost due to deletion and the maternal genes are silenced due to imprinting. PWS has the sister syndrome Angelman syndrome that includes maternally deleted and paternally imprinted genes in the same genetic region.
Signs and symptoms
Clinical features and signs
Holm et al. (1993) describe the following features and signs as pretest indicators of PWS, although not all will be present.
In utero:
- Reduced fetal movement
- Frequent abnormal fetal position
- Occasional polyhydramnios (excessive amniotic fluid)
At birth:
- Often breech or caesarean births
- Lethargy
- Hypotonia
- Feeding difficulties (due to poor muscle tone affecting sucking reflex)
- Difficulties establishing respiration
- Hypogonadism
Infancy:
- Failure to thrive (continued feeding difficulties)
- Delayed milestones/intellectual delay
- Excessive sleeping
- Strabismus
- Scoliosis (often not detected at birth)
Childhood:
- Speech delay
- Poor physical coordination
- Hyperphagia (over-eating) from age 2 – 8 years. Note change from feeding difficulties in infancy
- Excessive weight gain
- Sleep disorders
- Scoliosis
Adolescence:
- Delayed puberty
- Short stature
- Obesity
- Extremely flexible
Adulthood:
- Infertility (males and females)
- Hypogonadism
- Sparse pubic hair
- Obesity
- Hypotonia
- Learning disabilities/borderline intellectual functioning (but some cases of average intelligence)
- Prone to diabetes mellitus
- Extreme flexibility.
General physical appearance (adults)
- Prominent nasal bridge
- Small hands and feet with tapering of fingers
- Soft skin, which is easily bruised
- Excess fat, especially in the central portion of the body
- High, narrow forehead
- Almond shaped eyes with thin, down-turned lips
- Light skin and hair relative to other family members
- Lack of complete sexual development
- Frequent skin picking
- Striae
- Delayed motor development
Read more detail at Wikipedia
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