Low-level hyperinsulinism with hypoglycemic spells in an infant with mosaic Turner syndrome and mild Kabuki-like phenotype: a case report and review of the literature.

BACKGROUND: Impaired glucose tolerance and type 2 diabetes are well-known features in patients with Turner syndrome. To the best of our knowledge, there is only one reported case of hyperinsulinemic hypoglycemia associated with a complex mosaic Turner syndrome available in the current literature. PATIENT: We report on the case of a 13-month-old girl with a complex mosaic Turner genotype and mild hyperinsulinemic hypoglycemia responsive to diazoxide therapy. RESULTS: Cytogenetic analyses showed two or possibly three cell lines. Sixty percent of the cell lines had a 45,X genotype and the rest had 46,XX with a marker ring chromosome. Diagnosis of a mosaic Turner syndrome and mild Kabuki-like phenotype was confirmed. CONCLUSIONS: Despite the rareness of this case, clinicians should be aware of the possibility of hyperinsulinemic hypoglycemia in patients with Turner syndrome to prevent further brain damage caused by hypoglycemic episodes and seizures. Although the mechanism leading to hyperinsulinism in this condition is still unknown, the present report discusses this rare presentation and gives an overview on the current literature regarding this case.