Major criteria

Characteristic facial features (may include almond-shaped eyes, down-turned mouth, narrow bifrontal diameter, strabismus, thin upper lip; see Figures 1 and 2)

Developmental delay

Feeding problems/failure to thrive during infancy

Hypogonadism (may include cryptorchidism, hypoplastic scrotum, and small testes in males; hypoplastic labia minora and clitoris in females; and pubertal deficiency)

Infantile central hypotonia

Rapid weight gain between 1 and 6 years of age

Minor criteria

Decreased fetal movement and infantile lethargy

Esotropia, myopia

Hypopigmentation

Narrow hands with straight ulnar border

Short stature (compared with family members)

Skin picking

Sleep disturbance/sleep apnea

Small hands and feet

Speech articulation defects

Thick, viscous saliva

Typical behavioral problems