Prader-Willi Syndrome

Prevalence: 1:25,000

Incidence: 1:10,000-15,000

Racial prevalence: None

Gender predominance: Similar frequency in both sexes and all races

Most common syndromic form of obesity, affects 350,000–400,000 individuals worldwide

Annual death rate is 3% versus 1% in the general population, primarily due to respiratory arrest

Infantile hypotonia, hypoventilation, and breathing difficulty

Potential for difficult intubation and aspiration risk

Worsening of obstructive/central sleep apnea and abn ventilatory responses to hypoxia, hypercarbia, and bronchospasm

Bradycardia, ventricular arrhythmias (PVCs)

Postop resp insufficiency

Potential risk of rhabdomyolysis with succinylcholine

Aberrant thermoregulation: Hyperthermia and MHS-like syndrome

Glucose intolerance or DM

Abn short and restricted neck mobility, limited mouth opening and difficult intubation

Poor vascular access and intraop positioning

Systemic and pulm Htn, conduction defects, RBBB cor pulmonale, and dilated cardiomyopathy

Restrictive lung disease (obesity, kyphoscoliosis) and reactive airways

Presents in two stages: Infantile central hypotonia, FTT, and delayed developmental milestones. Childhood stage presents with obesity (BMI >97th percentile in a child and ≥30% in an adult), skeletal abn (dysmorphic, short stature, short hands and feet, scoliosis), hypogonadism, and hypothalamic dysfunction.

Restrictive pulmonary disease results from muscle weakness, obesity, and kyphoscoliosis. It starts in early childhood and is present in 80–90% of pts >30 y of age.

CV system: Htn in 17–32%; myocardial hypotrophic hypokinetic syndrome.

Central thermodysregulation: May develop hyperpyrexia.

Cognitive problems: Mild to moderate mental retardation. Mean IQ in 60s–70s; some individuals have normal intelligence.

Behavior problems of oppositional behavior, emotional lability, aggressive and violent behavior; obsession with food and compulsion to eat. Psychosis found in 5–10% of adults.

High threshold for pain.

A complex genetic disorder; paternally inherited via 15q11–q13 deletion (65–70%), maternal uniparental disomy 15 (20–30%) and imprinting defect (1–3%). GH deficiency.