Achondroplasia, Dwarfism

1 per 15,000 to 40,000 births worldwide

Females ≥ males

No race predilection

Most common type of dwarfism

Cervical spine instability

Spinal cord compression

Cardiopulmonary disease

Difficult airway and ventilation

Central and/or obstructive sleep apnea

Cervicomedullary compression and foramen magnum stenosis

Spinal cord and nerve root compression

Restrictive lung disease

Pulmonary hypertension, cor pulmonale

Results from overactive FGFR3, leading to inhibition of cartilage proliferation, leading to characteristic disproportionate dwarfism with relative macrocephaly, frontal bossing, midface hypoplasia, spine deformations, long narrow trunk, short extremities, and trident hands.

Average adult height is 4 feet 4 in. for males, 4 feet 1 in. for females.

Average adult weight is 120 lbs (55 kg) for males, 100 lbs (45 kg) for females.

Atlantoaxial instability, cervicomedullary compression, foramen magnum or spinal stenosis leading to cord compression and cauda equina syndrome may require neurologic intervention.

Brainstem compression contributes to central apnea while midface structural abnormalities lead to obstructive sleep apnea.

Kyphoscoliosis and rib cage deformities lead to restrictive lung disease.

Chronic hypoxia and hypercarbia from restrictive lung disease and sleep apnea lead to pulmonary hypertension and cor pulmonale.

Increased mortality from resp and neuro complications during childhood.

Heart-disease-related mortality approaches 10 times the general population in ages 25 to 35.

Intelligence is usually normal; overall life expectancy is decreased by 10 y.