Leprechaunism is otherwise known as the Donohue syndrome or dwarf dwarfism. It is a rare genetic disease and only a few dozen cases have been well described in history. It is associated with strong insulin resistance, which is why some say it is the most extreme stage of diabetes.
symptoms
The disease has its name for a reason, external symptoms can be seen with the naked eye. Children suffering from this syndrome are compared to dwarfs – and it’s not just about short stature and low birth weight. The faces of the sick have characteristic elven features. Their heads are smaller, their eyes are much larger than usual, and they are set wide apart. The nose is often hooked with wide nostrils. The lips are prominent with fleshy lips. In addition, there are large, low-set, sometimes pointed ears. In addition, the skin becomes gray and is excessively hairy.
Other visible physiological changes in people with Donohue syndrome are enlarged genitals and enlarged breasts in girls. Often there is also a dilated chest and disproportionately large feet and hands. Affected people have underdeveloped muscle tissue and practically no body fat, but there is an excessive amount of skin that sometimes forms folds. In addition, there are a number of changes in internal organs, including excessive growth of the pancreas and numerous changes in the ovaries and breasts.
The basis of the disease
The underlying disease is dysfunction of the insulin receptor, which leads to severe insulin resistance. Insulin is a hormone produced in the pancreas. Its role is to regulate the carbohydrate metabolism in the blood. When the amount of glucose in the blood rises after a meal, the pancreas secretes insulin, which affects the conversion of glucose into glycogen.
Usually, insulin resistance is associated with diabetes. As a result, the sensitivity of the liver, muscles and adipose tissue to insulin decreases. In Donohue syndrome, insulin sensitivity is close to zero.
People with leprechaunism have a rare mutation on chromosome 19. The gene that encodes the insulin receptor is modified. As a result of this mutation, the body’s cells cannot detect the insulin in the blood, so it cannot penetrate inside them, where the conversion of glucose into glycogen takes place. This results in a very high concentration of unmetabolized insulin in the blood. To compensate for the excess insulin, the pancreas produces increased amounts of glucagon (a hormone that works opposite to insulin). Her over-reactivity eventually leads to organ hypertrophy.
The secretion of estrogens is also disturbed in the course of the disease. It is the elevated levels of these hormones that cause changes in the sex organs and mammary glands of those affected.
It has also been suggested that the high concentration of insulin outside the cells reduces the activity of growth hormone, which causes the patients to suffer from developmental disorders.
The frequency of occurrence
Donohue syndrome is an autosomal recessive disease. This means that for a child to be born with the defect, both parents must be carriers of the abnormal gene. These parents have a 25% chance of conceiving a sick child. For this reason, leprechaunism is extremely rare – on average, in one child per 4 million live births. Since the likelihood of unrelated parents developing the abnormal gene is very low, most of the reported cases are children of blood-tied parents. In the described cases, it was usually a cousin or second cousin.
Diagnosis
Due to the fact that leprechaunism is a disease of genetic origin, particular attention should be paid to pregnancies of people who have a case of this disease in the medical history of the family – especially when conception was achieved as a result of contacts between relatives.
The diagnosis can be made while still pregnant. To confirm the disease, amniotic fluid should be collected and then a DNA test performed. If the test has not been performed, the stopping of fetal growth around the seventh month of pregnancy should be of concern.
Postpartum diagnosis is usually based on observation of physical characteristics. To confirm that a patient suffers from Donohue syndrome, a blood test is performed (patients have severe hypoglycemia).
Course of illness
Donohue syndrome is incurable. Mortality is very high among affected children. Patients usually live for several months, but there have also been reports of children who survived several years. These were patients with rudimentary insulin receptor functionality. Caring for a patient comes down mainly to administering an appropriate diet (similar to that used in people with type 2 diabetes). In addition, pharmacological agents are used. People with properly functioning growth hormone receptors are also given this substance.
Medical advances also make it possible to use experimental therapies, including gene therapy. At this stage of research, however, it is not possible to unequivocally assess its effectiveness in people with leprechaunism.
Tekst: Andrzej Dębski