This is a rare inherited condition characterized by the short stature resulting from the failure to generate the insulin-like growth factor I (IGF1) in response to growth hormone (GH). Although the affected infants appear to be close to normal size, they grow slowly resulting in the very short stature. Laron Syndrome also presents addition symptoms such as delayed puberty and hypoglycemia in infancy. There are only around 350 cases diagnosed with this syndrome globally.
Causes
Laron Syndrome develops as the result of a mutation in the gene GHR which is responsible for the production of the growth hormone receptor. This protein is particularly present in the liver cells. When the receptor attaches to the growth hormone, it stimulates the production of another hormone known as the insulin-like growth factor (IGF-I) which are essential for the normal growth of several parts of the body. The genetic mutation can affect the receptor’s ability to attach to the growth hormone and as the result, the cells are not able to produce IGF-I. This disruption affects the normal growth process of several tissues of the body. Hence, the short stature results when the growth of the bones cannot be adequately stimulated. Most cases are inherited in an autosomal recessive pattern meaning both the copies of the gene from the parents are defective.
Symptoms
The very short stature is the common characteristic feature of Laron Syndrome. The affected individual typically reaches the maximum height of around 4.5 feet. Additional features include reduced muscle strength, low blood sugar (hypoglycemia) in infancy, obesity, short limbs, delayed puberty, thin hair, dental problems and small genitals. The distinctive facial features include the sunken bridge of the nose, protruding forehead and the slight blue tint that appears on the whites of the eyes. Research indicates that these affected individuals appear to have reduced risk of cancer and type 2 diabetes.
Diagnosis
The diagnosis of Laron Syndrome is based on the identification of the features characteristic of this condition. Additional tests may be necessary to confirm the diagnosis and to rule out other possible causes. The tests include blood analysis that determines the levels of certain hormones such as the growth hormone and insulin-growth factor I which are often abnormal among these affected cases. The genetic testing can also confirm the diagnosis by detecting the genetic mutation that is responsible for causing this syndrome.
Treatment
Currently, there is no cure for Laron Syndrome. The treatment is based on improving the growth of the affected children and includes the subcutaneous injection of insulin-like growth factor 1 (IGF-I). This treatment can stimulate the linear growth, improves the metabolic problems and the brain growth. The treatment can also reduce cholesterol and increase the muscle growth.
References
https://ghr.nlm.nih.gov/condition/laron-syndrome#statistics
https://rarediseases.info.nih.gov/diseases/6859/laron-syndrome
