GTR Home > Conditions/Phenotypes > Achondroplasia

Disease characteristics

Excerpted from the GeneReview: Achondroplasia
Achondroplasia is the most common process resulting in disproportionate small stature. Affected individuals have short arms and legs, a large head, and characteristic facial features with frontal bossing and midface retrusion (formerly known as midface hypoplasia). In infancy, hypotonia is typical, and acquisition of developmental motor milestones is often both aberrant in pattern and delayed. Intelligence and life span are usually near normal, although craniocervical junction compression increases the risk of death in infancy.

Associated genes

Clinical features

  • Apnea
  • Hyperhidrosis
  • Trident hand
  • Long thorax
  • Generalized joint laxity
  • Recurrent otitis media
  • Kyphosis
  • Limb undergrowth
  • Midface retrusion
  • Anteverted nares
  • Intrauterine growth retardation
  • Rhizomelia
  • Malar flattening
  • Short femoral neck
  • Lumbar kyphosis in infancy
  • Limited elbow extension
  • Hydrocephalus
  • Obesity
  • Sudden cardiac death
  • Macrocephaly
  • Limited hip extension
  • Abnormality of the teeth
  • Conductive hearing impairment
  • Abnormality of the ribs
  • Narrow chest
  • Abnormality of the metaphyses
  • Acanthosis nigricans
  • Brachydactyly syndrome
  • Muscular hypotonia
  • Motor delay
  • Megalencephaly
  • Joint hypermobility
  • Frontal bossing
  • Ventriculomegaly
  • Neurological speech impairment
  • Brain stem compression
  • Skeletal dysplasia
  • Small foramen magnum
  • Upper airway obstruction
  • Lumbar hyperlordosis
  • Genu varum
  • Flared metaphyses
  • Elbow dislocation
  • Hyperlordosis
  • Abnormal form of the vertebral bodies
  • Spinal canal stenosis
  • Depressed nasal bridge
  • Spinal stenosis with reduced interpedicular distance
  • Neonatal short-limb short stature
  • Infantile muscular hypotonia
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