Leprechaunism
Leprechaunism“Leprechaunism”
Leprechaunism is an extremely rare genetic disease that was first identified in 1948 by W.L. Donohue. There have only been 49 cases reported worldwide since is first reporting in 1948 until 1987. This disease is also known as Donohue Syndrome, in his honor.
Most Leprechaunism patients die by the age of 10 months, although there have been cases of patients living until 11 years of age. This is because several different mutations in the insulin receptor gene can cause Leprechaunism, and the severity of the mutation determines the severity of the phenotype. Both male and female patients are affected by this disease. The disease is known as Leprechaunism because infants with the disease have an elf-like face and their growth is severely retarded. This is due to the patients being completely resistant to the effects of insulin.
Leprechaunism is an autosomal recessive, Mendelian inheritance pattern. As stated before, both males and females can be affected. Its occurrence is associated with consanguineous relationships. A consanguineous relationship means that the parents are genetically related (e.g. first cousins).
Clinical traits are as follows:
Hyperpigmented skin or as otherwise known, Acanthosis nigricans. This symptom is not exclusive to Leprechaunism, as it is caused by high insulin levels. This pigmentation normally occurs in areas of the body where flexing and bending occurs, such as the back of the neck.
Reddening of the skin or erythema. This is caused by localized irritation. Most often the areas of the body most affected are those such as the gluteal cleft, groin area, and other places that friction might occur. It is not limited to these areas as it occurs on any other part of the body as well, such as the extremities.
Pincer nails. This is where the nails of the feet and hands have an increased inward folding. This often gives the visual effect of claws in severe cases.
Hirsutism or excessive hair growth.
Gynecomastia or abnormal swelling of the breasts with prominent nipples. This effect is the result of excessive production of estrogen.
Enlarged genitalia.
Dysmorphic facial features including large, low-set ears, depressed nasal bridge with a broad nasal tip and flared nares, and thick lips.
A severe lack of subcutaneous fat, abdominal distention, and loose skin.
Leprechaunism is caused by defects in the insulin receptor (INSR). This receptor is a transmembrane protein. In 1993, the human insulin receptor was found to be located at the locus 19p13.3, or on the short arm of chromosome 19, in section one-three point three. The insulin receptor is a tetramer of 2 alpha and 2 beta subunits joined by disulfide bonds. The coding sequence consists of 22 exons, with 11 exons coding for the alpha subunit and 11 coding for the beta subunit. It is postulated that the class I MHC heavy chain is...
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