Table 2. [Prader-Willi Syndrome: Frequency of Select Features]. - GeneReviews®

Feature	% of Persons w/Feature	Comment
Infantile hypotonia	95%-100%	Assoc w/poor suck; results in poor weight gain w/o feeding support
Dysphagia	90%-100%	Typically present at birth & persists to adulthood
Motor delay	90%-100%
Language delay	90%-100%	Incl abnormal speech articulation, speech apraxia
Intellectual disability	90%-100%	Most w/mild disability; ranges from severe learning disabilities to significant cognitive disability
Endocrine manifestations	90%-100%	Hypogonadism, abnormal pubertal development, growth deficiency, diabetes mellitus, hypothyroidism
Hyperphagia & obesity	90%-100%
Characteristic behavior profile	70%-90%	Anxiety, tantrums, rigidity, OCD, manipulative behavior, autistic features, ADHD; psychosis becomes evident in young adults, esp those w/UPD 15
Increased pain threshold	60%-80%	May mask urgent medical issues
Dysmorphic facial features	50%-70%	May attenuate w/GH therapy; more common in persons w/15q deletion
Hypopigmentation	50%-70%	Primarily in those w/15q deletion
Skin picking	50%-60%	Decreases in older adults
Strabismus	40%-60%
Sleep abnormalities	30%-40%	Central apnea (in infants), obstructive sleep apnea, daytime sleepiness, narcolepsy
Scoliosis	40%-80%
Seizures	10%-20%	Typically generalized & treatable

Feature

% of Persons w/Feature

Comment

Infantile hypotonia

95%-100%

Assoc w/poor suck; results in poor weight gain w/o feeding support

Dysphagia

90%-100%

Typically present at birth & persists to adulthood

Motor delay

90%-100%

Language delay

90%-100%

Incl abnormal speech articulation, speech apraxia

Intellectual disability

90%-100%

Most w/mild disability; ranges from severe learning disabilities to significant cognitive disability

Endocrine manifestations

90%-100%

Hypogonadism, abnormal pubertal development, growth deficiency, diabetes mellitus, hypothyroidism

Hyperphagia & obesity

90%-100%

Characteristic behavior profile

70%-90%

Anxiety, tantrums, rigidity, OCD, manipulative behavior, autistic features, ADHD; psychosis becomes evident in young adults, esp those w/UPD 15

Increased pain threshold

60%-80%

May mask urgent medical issues

Dysmorphic facial features

50%-70%

May attenuate w/GH therapy; more common in persons w/15q deletion

Hypopigmentation

50%-70%

Primarily in those w/15q deletion

Skin picking

50%-60%

Decreases in older adults

Strabismus

40%-60%

Sleep abnormalities

30%-40%

Central apnea (in infants), obstructive sleep apnea, daytime sleepiness, narcolepsy

Scoliosis

40%-80%

Seizures

10%-20%

Typically generalized & treatable

From: Prader-Willi Syndrome

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Adam MP, Feldman J, Mirzaa GM, et al., editors.

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