Leprechaunism - a case report.

Sir,

Leprechaunism or Donohue's syndrome is a rare condition occurring in less than one in a million births. Marked hypertrichosis, characteristic facies, loss of subcutaneous tissue and low birth weight are characteristic of this morbid condition.[1] Fibroblasts from the skin of such patients are resistant to the action of insulin and this result in postprandial hyperglycemia.[2]

An 11 month old marasmic male child was refered to dermatology from the Endocrinology department. The infant was suffering from fever and cough. History revealed consanguinity of the parents. Birth was uneventful and he had weighed 2.2 Kg. There was no significant drug history of the mother during pregnancy. On presentation, the patient weighed 3.7 Kg and had a remarkable facies [Figure 1] with enlarged head, hypertrichosis of forehead and sides of the face, flaring nostrils with flattened nasal bridge. Skin over neck region was thick and was thrown into several folds [Figure 2]. Ears were large, low-set and whole body was covered with a fine pelage [Figure 3]. The abdomen was protuberant with an everted umbilicus, and the extremities were thin and elongated, but emaciated. The penis was enlarged [Figure 4]. Both testes were undescended. The child could not stand unsupported and milestones were delayed. The blood count revealed a total leukocyte count of 16,700/cmm with a predominance of lymphocytes. Fasting blood glucose was 66 mg/dl and insulin level in the fasting state was 23 microunits/ ml. Serum alkaline phosphatase, an enzyme found in the liver and bones, displayed a level of 9 KA units and was low for the patient's age indicating derangement of hepatobiliary system or reduced bone age. X-ray of the extremities, urinary amino acids and ultrasonography of the abdomen was planned, but the child deteriorated dramatically and died just a day after.

Figure 1

Characterestic elfin facies of child with Leprechaunism

Figure 2

Skin over neck region thrown into several thick folds

Figure 3

Large ear of infant and whole body covered with fine hairs

Figure 4

Thin and emaciated extremity with protuberant abdomen and large penis

Leprechaunism was first described by Donohue (1948)[3] and since then it remains mainly a clinical diagnosis with the criterion outlined by Donohue and Uchida standing the test of time. Conditions mentioned for the diagnosis are characteristic gnome like facies, dystrophy with failure of ossification and marasmus, atrophy of lymphoid structures with a liability to infection and an abnormal carbohydrate metabolism.[3] Other distinctive features, which may help are consanguinity of the parents, growth retardation and tubular dilatation of the kidneys. Research indicates that the disease is genetically determined and is transmitted as autosomal recessive trait.[4] Chromosomal abnormality has been reported in very few instances of Donohue's syndrome, and in one case the classical features of this condition were reported with chromosome mosaicism.[4] Others have observed that mutations in corresponding gene is responsible for the disorders Leprechaunism and Rabson-Mendenhall (R-M) syndrome. Leprechaunism children die within 1year of age. Few have been known to survive till older age. A male patient of Leprechaunism suffering ocular manifestations in the form of subluxated mature cataract, retinal detachment, high myopia, and optic atrophy has exceptionally survived to the age of 29 years. Patient had residual insulin receptor function, which possibly increased his longevity.[5]

Those of the R-M syndrome suffer milder aliment and can survive upto 15 years of age.[6] R-M syndrome differs from leprechaunism by being less severe, and by the presence of premature and dysplastic dentition, coarse facial features, gingival hyperplasia and pineal hyperplasia.[6]

Acanthosis nigricans seen in this subject is a consequence of the hyperinsulinemia. The phenotypic features of the subject is a result of reduced binding capacity of extracellular growth factor (EGF) receptor, producing increased blood levels of EGF. The reduced EGF receptor function could be related to altered insulin receptor function itself.[7] Signs of hyperandrogenism could be due to excessive production of androgen, induced by insulin.

The rare genetic entity, Leprechaunism requires early diagnosis and genetic counseling. Awarenes of the typical clinical features with even minimum laboratory investigations can help the physician identify this condition, and institute early supportive management.