Leprechaunism is an outdated name for a rare medical condition more properly called Donohue syndrome. This syndrome affects the appearance of the person and results in pointed ears, small stature and a short lifespan. It is caused by a genetic defect in insulin receptors that affect growth.
First described in 1948 by Dr. W.L. Donohue, the cause of leprechaunism was not well known until the late 1970s, when it was found that insulin receptors were abnormal. By the 1980s, a genetic cause was suspected, and doctors realized that a recessive gene was involved. A recessive gene is a gene that has a mutation that does not cause medical problems if it is inherited from only one parent. If both parents have a mutated form of the gene, then the child can inherit both abnormal genes and develop the condition.
Insulin receptor genes are involved in the development of leprechaunism. Usually, the outside of a healthy cell has a receptor to which insulin attaches. Kids who have the syndrome cannot make efficient insulin receptors. This syndrome technically is a severe form of diabetes.
Blood sugar levels are controlled partially by insulin. If the blood contains too much insulin, then the body's growth is adversely affected. As a response to the abnormal insulin levels, other hormones are produced by the body, and they can also affect bodily growth. This unbalanced growth system results in the unusual facial features and stature of the affected child.
The unusual name of leprechaunism, first attached to the condition, stemmed from the physical appearance of the affected child. Small and pointed features and wide-spaced eyes, much like a mythological elf, are characteristics of children who have Donohue syndrome. They also are smaller than usual, and because of the insulin processing problems inherent in the disease, they do not put on weight or develop muscle in the same way as unaffected children. The abnormal levels of other hormones in the body might also cause the children to have larger-than-normal hands, feet, breasts and sex organs.
Most children born with this condition die before they reach 1 year old. Death is normally caused by an inability to absorb nutrients from food or by infection. Children who have this syndrome and who live into their teens typically have physical disabilities and mental impairment. Genetic counseling is available for potential parents who carry the genetic mutations, and genetic testing of the fetus before birth is possible.