The main cause of proportionate short stature is being born to parents of small stature. However, in some rare instances, the condition can be the result of the body not producing enough growth hormone. This specific type of the disorder can emerge not only in childhood but later adulthood.
In cases where a growth hormone deficiency has emerged in adulthood, the disorder can often be linked to a potential tumour or blockage in the pituitary gland. This is a small pea sized gland located in the brain, which helps to produce and administer growth hormone to the body. In other rare cases, adults may experience a reduction in growth hormone administration due to exposure to radiation therapy on the brain.
Hormone deficiencies amongst children can also occur due to irregularities in the pituitary gland, which cause the reduction or prevention of growth hormone release. In some instances, this can occur as a result of a head injury or illness sustained soon after birth. However, in some instances the cause of the growth hormone deficiency may be difficult to identify.
Additional causes of proportionate short stature include disorders such as Turner’s syndrome. This occurs only in girls and is caused by a defect in the chromosomes, which restricts both body and sexual development. In other instances, chronic illnesses which affect the lungs, kidneys or heart can lead to proportionate short stature. Furthermore, treatment for chronic conditions such as arthritis can often slow the release of growth hormones and lead to further growth related problems.
For those with a disproportionate short stature condition, the underlying cause of the problem is usually linked to a genetic mutation. Children with the condition may be born to parents of average height, but may find they have inherited a spontaneous genetic mutation which causes certain genes within the body to hinder the development of bones and cartilage and in turn restrict proportionate growth. It is important to note that in some cases those with a disproportionate short stature condition can pass it on to their children and, on the whole, the disorder is a congenital one.
The most common cause of disproportionate short stature is something called achondroplasia, a condition that affects around seven in ten of those with this disorder. This causes the development of a regular skeletal trunk with shortened limbs, most prominently in the thighs and upper arms, as well as an enlarged skull, forehead and some feet and spine abnormalities.