= deletion of short arm of 5^th chromosome (5 p)

• generalized dwarfism ← marked growth retardation
• failure to thrive
• peculiar high-pitched cat cry (hypoplastic larynx)
• antimongoloid palpebral fissures; strabismus
• profound mental retardation; round facies; low-set ears

Associated with: congenital heart disease (obtain CXR!)

• agenesis of corpus callosum
• microcephaly
• hypertelorism
• small mandible
• faulty long-bone development
• short 3^rd, 4^th, 5^th metacarpals
• long 2^nd, 3^rd, 4^th, 5^th proximal phalanges
• horseshoe kidney

Dx: made clinically