Laron syndrome General description
Laron syndrome (Laron dwarfism) – autosomal recessive illness with a short stature that appears because of body’s inability to use growth hormone (GH) and it is caused by defects of the GH receptor. This can be the result from mutations in the GHR gene.
This disease can cause resistance to insulin and rare mellitus type of diabetes. The syndrome was first described by Israeli researcher Zvi Laron in 1966. This disorder is very rare and only 350 people were affected by it in the world according to the recent statistics. The big part of them (100 people) are in southern Ecuador.
One of the causes of the disease is relationships between relatives. Type of inheritance of the disease is autosomal recessive, so the mutant gene which is located at the asexual chromosome, should be inherited from both parents. They both have one copy of the mutated gene, but they don’t experience any symptoms of Laron syndrome. It means that the chance of having a child with the condition in such family is 25%, and it will not depend on the age of the parents, the child's sex, the pregnancy and childbirth. Less often one copy of the mutated gene can cause this disorder, so it means that only one parent of affected person has it.
Symptoms of Laron syndrome
Affected people are born with normal size, but then they don’t grow up enough during childhood. Adult male will be only 4.5 feet tall and female 4 feet. Also, untreated Laron syndrome will cause endurance and reduced muscle strength, low blood sugar levels, fragile hair, small genitals, dental abnormalities.
People who suffer from this illness mostly have characteristic type of face with protruding forehead, blue tint in the whites of eyes, lowered bridge of the nose, undeveloped upper and lower jaws. Also they have short limbs, small hands and feet, rare hair, high voice.
In young years these individuals can have obesity. Sexual development is delayed, occurs spontaneously, so patients are fertile. But patients all have normal intelligence development.
The symptoms can be different even in affected members of one family.
Studies show that affected people have very low risk of cancer and type 2 diabetes. However, they don’t have an increased lifespan compared to non-affected individuals.
Diagnosis of Laron syndrome
Diagnosis of Laron disorder can be based on:
- clinical picture
- bone age backlog from the real age of a person
- attacks of hypoglycemia
- normal or high levels of growth hormone
- low levels of somatomedins
- increased stimulated level of growth hormone
- somatomedins do not increase after the injection of growth hormone.
To identify normal or high levels of growth hormone, you can use hormonal tests. It will be low in case if mutations present in the extracellular domain and normal or high if mutations are in the intercellular domain.
Treatment of patients with Laron syndrome is not very effective. Nowadays people most commonly use a recombinant insulin-like growth factor (somatomedin) as treatment.
Some representatives of healthcare organizations believe that treatment with biosynthetic IGF-1 can be used as effectively, but it should be taken before puberty.
A lot of drug companies have created some new medicines to treat Laron illness. For example, IGF-1 affected people have the option of using the product Increlex (mecasermin) provided by US company Tercica or IPLEX (Mecasermin rinfabate) as far as we know should be apporved by the US Food and Drug Administration.
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