The synonym for this syndrome, leprechaunism, is
derived from “leprechaun,” the name of a mythical little hairy elf
originating from the Irish folklore. Patients have an elfin or gnome-like
face with microcephaly, protuberant and low-set ears, large, wide-set eyes,
high arched palate, thickened lips, and severely diminished subcutaneous fat
(general lipodystrophy) and muscle mass. Skin abnormalities include
hypertrichosis (also reflected in the name leprechaun), acanthosis
nigricans, and pachyderma. Insulin resistance characterizes the metabolic
abnormalities, such as severe hyperinsulinemia, postprandial hyperglycemia,
and paradoxical fasting hypoglycemia. Intrauterine and postnatal growth
retardation seem to result from a diminished response to growth hormone, at
least partially because of downregulation of growth hormone receptors by
high insulin levels. The genitalia are enlarged, and cystic changes in the
gonads occur frequently in girls. The abdomen often is distended, and the
presence of umbilical and/or inguinal hernias is not uncommon. Some patients
have cardiac involvement, such as atrial septal defect or, more commonly,
myocardial hypertrophy, which may be severe. Although some patients survived
for several years, most die of severe failure to thrive with recurrent
infections in the first year of life. Rare cases of survival beyond infancy
have been attributed to the presence of residual insulin receptor function.