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Related Subjects: |Autosomal Dominant |Autosomal Recessive

Mutations in the fibroblast growth factor receptor-3 (FGFR3) gene on chromosome 4. The prognosis for individuals with achondroplasia is generally good, with most leading normal, healthy lives. However, they may face certain health challenges, particularly related to spinal and respiratory issues, that require ongoing medical care. Life expectancy is typically normal, but careful management of potential complications is essential to ensure a good quality of life.

About

• A non-lethal form of chondrodysplasia
• Disorder of cartilage leading to reduced growth

Aetiology

• Genetic Mutation: Achondroplasia is caused by a mutation in the FGFR3 gene located on chromosome 4. This mutation leads to an abnormal form of the FGFR3 protein, which inhibits bone growth, particularly in the long bones.
• Inheritance Pattern: The condition follows an autosomal dominant inheritance pattern. Most cases are the result of new mutations, but it can be inherited from one affected parent. If one parent has achondroplasia, there is a 50% chance of passing the condition to their offspring.
• Pathophysiology: FGFR3 is normally involved in regulating bone growth by limiting the formation of bone from cartilage. In achondroplasia, the mutated FGFR3 gene results in overactive inhibition of this process, leading to the characteristic short limbs and other skeletal abnormalities.

Clinical

• Short Stature: Adults with achondroplasia typically have a height of around 4 feet (122 cm).
• Disproportionately Short Limbs: The arms and legs, particularly the upper arms and thighs, are short compared to the torso.
• Macrocephaly: An enlarged head with a prominent forehead and flattened nasal bridge.
• Spinal Issues: Kyphosis (curvature of the upper spine) and lordosis (curvature of the lower spine) are common, as is spinal stenosis, which can cause pain and neurological problems.
• Hypotonia: Reduced muscle tone, especially in infancy, which can lead to delays in motor development.
• Dental Problems: Crowded teeth and delayed dental development are often observed.
• Ear Infections: Recurrent otitis media is common due to narrow Eustachian tubes.

Management

• Monitoring Growth and Development: Regular follow-up with specialist, orthopod and neurologist, to monitor growth, development, and complications.
• Surgical Interventions: for complications such as spinal stenosis, limb lengthening (in some cases), or correcting spinal curvature.
• Physiotherapy: improve muscle strength, coordination, and mobility, particularly in children with hypotonia or motor delays.
• Hearing and Speech Therapy: children with recurrent ear infections or speech delays.
• Educational Support: education plans to accommodate any physical or developmental needs.
• Genetic Counseling: with families to discuss the inheritance patterns, recurrence risk, and implications for future pregnancies.

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