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Rare inherited condition caused by resistance to
insulin with growth deficiency and characterized by dysmorphic facies
(“elfin-like”), severe growth retardation, hirsutism, and multiple
endocrine disorders.
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Endocrine disorder characterized by resistance to insulin
caused by abnormal insulin receptors. First described by W.L. Donohue and
I.A. Uchida in 1954.
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Approximately 50 cases have been reported in the
literature, but the incidence is estimated to be approximately 1:4,000,000
live births.
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Autosomal recessive. The defective gene, which
is responsible for encoding of the insulin receptor, has been mapped to
19p13.2. Parental consanguinity is likely for this disorder.
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The primary defect in leprechaunism is located in
the insulin receptor, but a secondary associated defect probably is
responsible for growth failure because of an impaired response to endogenous
growth hormone. This finding may be explained by the fact that the
cytoplasmic subunit of the insulin receptor shares similarities with other
receptors that have tyrosine kinase activity (e.g., insulin-like growth
factor-1, epidermal and platelet-derived growth factor, and certain
protooncogenes).
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Clinical aspect and measurement of blood glucose and
insulin levels. Prenatal diagnosis is available.
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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.
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Obtain a blood sugar level prior to
going to the operating room. If cardiac disease is suspected, obtain an ECG
and an echocardiogram.
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General and regional anesthesia, in the
same newborn, for two different surgeries have been reported with no major
complications related to the type of anesthesia. Except for very short
surgeries, regular blood glucose measurements should be performed and a
dextrose-containing intravenous solution administered to detect and prevent
hypoglycemia, respectively. In the presence of hypertrophic cardiomyopathy,
tachycardia, hypotension, hypovolemia, and an increase in contractility must
be avoided.
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