Figure 1, left, The infant shows the typical "elfinlike" facies of leprechaunism with hirsutism, large, low-set ears, broad nasal tip and flared nares, and thick lips. Figure 1, right, Other prominent features present in this infant include reduced subcutaneous fat, prominent nipples, a distended abdomen, large external genitalia, and rectal prolapse.
Donohue1 and Donohue and Uchida2 were the first to describe this rare syndrome featuring dysmorphic facies, failure to thrive, hirsutism, and multiple endocrine abnormalities.2 Leprechaunism was the euphemistic name used to describe the "elfinlike" facies and poor growth characteristic of the syndrome. The dysmorphic facial features include large, low-set ears, depressed nasal bridge with a broad nasal tip and flared nares, thick lips, and hirsutism. The body habitus is striking with a marked lack of subcutaneous fat, generalized hirsutism, acanthosis nigricans, prominent nipples, enlarged genitalia, abdominal distention, and loose skin.3,4
The diagnosis of leprechaunism is usually made on the basis of the clinical appearance and laboratory evidence of hyperglycemia and extreme insulin resistance. Advances in molecular genetics have allowed the molecular basis of the syndrome to be delineated. The first insulin receptor gene mutation found in human disease was detected in an infant with leprechaunism.5 Insulin receptors are important for intrauterine growth, especially of muscle and fat. Mutation of the insulin receptor gene results in impaired insulin binding and altered receptor signaling resulting in intrauterine and postnatal growth restriction.6- 8
Excessive concentrations of epidermal growth factor found in affected infants are considered to be a factor that gives rise to hypertrophy of the skin, hypertrichosis, and prominence of the nipples.8 Other phenotypic and metabolic abnormalities may be the result of the combination of the lack of insulin receptor action and the overactivation of insulin-like growth factor 1 by insulin.9,10
Leprechaunism is inherited in an autosomal recessive fashion. Prenatal diagnosis is possible by DNA analysis of chorionic villus biopsy specimens for mutations in the insulin receptor gene.7
Infants with this rare syndrome usually die in infancy as a result of malnutrition and recurrent infections. Survival beyond early infancy has been attributed to the presence of residual insulin receptor function and the ability of pathologically elevated concentrations of insulin to transmit some signals through the homologous receptor for insulin-like growth factor 1.11 All infants are profoundly motor and mentally retarded.
Accepted for publication May 4, 1998.
Reprints: Hüseyin Özbey, MD, Department of Pediatric Surgery, University of Istanbul, Istanbul Medical Faculty, 34390, Capa-Istanbul, Turkey.
Picture of the Month. Arch Pediatr Adolesc Med. 1998;152(10):1032. doi: