Restricted growth (dwarfism) may be caused by many different medical conditions, and is more noticeable in some conditions than others.
Causes of proportionate short stature
The main cause of proportionate short stature (PSS) is being born to small parents.
A less common cause is the body not producing enough growth hormone, which is estimated to affect one in every 3,500 to 4,000 children.
This may be present at birth, because of problems with the pituitary gland (a pea-sized gland below the brain responsible for producing several important hormones) or as part of another condition. It can also start in childhood, as the result of an injury, a brain tumour or radiotherapy to the brain.
In about half of children with growth hormone deficiency, the cause is unknown.
Other possible causes of PSS include:
If your child is diagnosed with restricted growth, tests may be carried out to try to identify the underlying cause.
Read more about diagnosing restricted growth.
Causes of disproportionate short stature
Conditions associated with disproportionate short stature (DSS) are usually caused by a faulty gene. The affected genes stop the bones and cartilage developing properly, leading to restricted growth that is often noticeable from birth.
Many children born with DSS have parents of average height and the change to the gene happens by chance. However, people with conditions that cause DSS may pass their condition on to their children.
The most common cause of DSS is a condition called achondroplasia, which is estimated to affect around one in every 25,000 people.
Other conditions that cause DSS include:
- mucopolysaccharide disease
- diastrophic dysplasia
- spondyloepiphyseal dysplasia
- multiple epiphyseal dysplasia
- Conradi syndrome
- Ellis-van Creveld syndrome
You can read more about some of these rare conditions on the Restricted Growth Association website.