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. The growth hormone deficiency may be present at birth, due to problems with the pituitary gland (a pea-sized gland below the brain) or as part of another condition. Or it may start in childhood, as the result of an injury or disease affecting the head.
In about half of children with growth hormone deficiency, the cause is unknown. Growth hormone deficiency is estimated to occur in 1 in 3,500-4,000 children.
Other possible causes
Other possible causes of PSS include:
Disproportionate short stature
Conditions associated with disproportionate short stature (DSS) are usually caused by a faulty gene. Many children born with DSS have parents of average height and the change to the gene happens by chance. The affected genes stop the bones and cartilage developing properly, leading to restricted growth.
People with conditions that cause DSS may pass their condition on to their children. Conditions that cause DSS are usually present from birth.
The most common cause of DSS is a condition called achondroplasia. This causes shortened limbs (especially the upper arms and thighs), a large skull with prominent forehead, short hands and feet, and spinal abnormalities.
Other conditions that cause DSS include:
- mucopolysaccharide disease
- diastrophic dysplasia
- spondyloepiphyseal dysplasia
- multiple epiphyseal dysplasia
- Conradi syndrome
- Ellis-van Creveld syndrome
For information on any of these rare conditions, go to the Restricted Growth Association website.