What is PWS > Symptons & Characteristics

Prader-Willi Syndrome Symptoms

By Suzanne Cassidy, MD

Physical characteristics:

There is often a characteristic facial appearance with a narrow forehead, almond-shaped eyes, and a thin upper lip with downturned mouth. Scoliosis (S-shaped curvature of the spine) may develop. Many individuals have fairer coloring of hair, eyes and skin than other family members.

Growth deficiency:

People with PWS typically have short stature for the family and small hands and feet. Early growth may be below normal, and there is failure to have a pubertal growth spurt. Recent studies have documented insufficiency in growth hormone, and treatment can correct this problem.

Incomplete Sexual Development:

The small genitalia that characterize affected individuals are more easily identified in males, but affects both sexes.  Males often have undescended testicles and a small, poorly delineated scrotum; females have small labia minora and clitoris. Pubertal development is typically delayed and incomplete, and fertility is extremely rare and has occurred only in females.


Intellectual disability:

Learning and cognitive development are delayed. Although there is wide variability in abilities, the average IQ is in the 60’s. Most affected persons function in the mild intellectual disability range independent of tested IQ, and most are learning disabled.


Speech and language difficulties:

Cognitive capacity and probably also the extent of hypotonia affect this ability. Speech therapy may be helpful.

Balance and Coordination:

Fine motor skills usually are well developed, while gross motor skills remain limited.

High pain threshold and irregularities in body temperature control.  Most people with PWS are unaware of injury and infection because of blunted sensory mechanisms. Unexplained high or low temperatures may occur, and there is often insensitivity to environmental temperature.



Scratching and Picking:

Many individuals with PWS pick and scratch at sores and insect bites which, if not controlled, may become chronic sores and result in infection.


Behavior and Temperament:

Affected children tend to be loving, happy and compliant in early years, and then subtle changes typically lead to mood swings and behavior difficulties over time.  This often includes temper outbursts, stubbornness, rigidity, argumentativeness, and repetitive thoughts and behaviors. Social skills are often impaired. True psychosis occurs in a minority of affected older teenagers and young adults, but it usually responds well to treatment. Depression may result in later years when self-image issues emerge, particularly over the conflict between the drive for independence and the need for management.


Other Findings:

People with PWS may experience excessive daytime sleepiness and sleep apnea, particularly if obese. Eye abnormalities such as strabismus (cross-eyed), myopia (nearsightedness) or amblyopia (lazy eye) are common.


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