Ortho - Achondroplasia

Question 1

What causes achondroplasia?

Answer 1

Fibroblast growth factor receptor 3 gene mutation on chromosome 4

Spordic mutation or inheritance of abnormal copy

Autosomal dominant

Homozygous gene mutations are fatal and not compatible with life

Question 2

What do FGFR3 gene mutations cause?

Answer 2

Abnormal functions of the epiphyseal growth plates

Restricts bone growth in length, leads to short bones and short stature

Only affects long bones

Question 3

What are the features of achondroplasia?

Answer 3

• Long bones affected
• Short digits
• Bow legs (genu varum)
• Disproportional skull
• Foramen magnum stenosis

Question 4

Why is the skull disproportionate?

Answer 4

Some bones grow by endochondral ossification leading to:
- Flattened mid-face
- Flattened nasal bridge
- Foramen magnum stenosis

Cranial vault grows by membranous ossification leading to normal growth causing :
- Frontal bossing

Question 5

What are some associations with achondroplasia?

Answer 5

• Recurrent otitis media
• Kyphoscoliosis
• Spinal stenosis
• OSA
• Obesity
• Foramen magnum stenosis - leads to cervical cord compression and hydrocephalus

Question 6

How is achondroplasia managed?

Answer 6

MDT to support patient

Question 7

What is the prognosis in achondroplasia?

Answer 7

Normal life expectancy if not affected by complications

Tendency to be overweight due to small stature

Psychosocial implications