Donohue syndrome (leprechaunism; OMIM *246200) is a rare and often lethal autosomal recessive disease caused by mutations in the <i>INSR</i> gene. We report the case of a 29-year-old pregnant woman, primigravida, who was referred at 33 weeks of gestation for severe intrauterine growth restriction (IUGR). Ultrasound examination found severe IUGR associated with an obstructive hypertrophic cardiomyopathy (HCM), confirmed postnatally. The newborn’s blood glucose level fluctuated from fasting hypoglycemia to postprandial hyperglycemia. The infant was found to be homozygous for a novel missense pathogenic variant, c.632C>T (p.T211l), in exon 2 of the <i>INSR</i> gene, predicted to result in an abnormal insulin receptor. To our knowledge, this is the first report of leprechaunism being revealed by IUGR and HCM during the prenatal period. Clinicians should keep in mind that the association of these prenatal signs could indicate leprechaunism and specific early neonatal management could be proposed, in particular with recombinant human insulin-like growth factor-I.
Objectives
Serious hyperinsulinemic hypoglycemia (HH) is generally the main initial symptom of hyperinsulinism. Epilepsy, without any overt feature of hypoglycemia, might be a very rare initial presentation of late-onset isolated hyperinsulinism.
Case presentation
We describe a case of late-onset HH in a 15-year-old boy with a history of idiopathic generalized epilepsy, now named genetic generalized epilepsy (IGE/GGE), beginning with a tonic–clonic seizure at the age of 11 years. Subsequently, absences with rare eyelid myoclonia were recorded on electroencephalogram (EEG), followed by episodes of impaired consciousness with facial myoclonia. Neurological status was normal except attention-deficit hyperactivity disorder (ADHD). At the age of 15 years, an episode of slight alteration of consciousness with neurovegetative signs could be recorded, which did not correspond to an absence status. Hypoglycemia due to hyperinsulinism was documented (clinically, biologically, and genetically). Diazoxide treatment resolved the glycopenic symptoms, the non-hypoglycemic seizures and normalized brain electrical activity allowing complete withdrawal of antiepileptic medication.
Conclusions
Epilepsy can be a very rare initial feature of HH starting in childhood. The occurrence of atypical features in the context of GGE as “absence statuses” with unusual vegetative symptoms and facial myoclonia might be suggestive for HH. Careful assessment and specific treatment are necessary to prevent hyperinsulinism related brain damage. Our case showed that diazoxide might also resolve seizures and normalize EEG.
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