A case with neonatal hyperinsulinemic hypoglycemia: It is a characteristic complication of Sotos syndrome.

Sotos syndrome (SoS, OMIM #117550) is an overgrowth syndrome. Deletions or intragenic mutations of the NSD1 , which is located at chromosome 5q35, are responsible for more than 75% of SoS. Conventionally, neonatal hypoglycemia was reported briefly as one of the infrequent symptoms of SoS. However, Matsuo et al. published a report describing five patients with SoS who presented with transient hyperinsulinemic hypoglycemia (HIH) in the neonatal period. We report on an additional patient of SoS, who presented transient HIH in the neonatal period. All of this patient and previous patients have microdeletions at the 5q35 chromosome. Therefore, we examined the following three in considering the possibility that other factor than NSD1 caused HIH. 1) This patient had no mutation of four currently known HIH related genes, ABCC8, KCNJ11, GLUD1, and GCK. 2) He had no further deletion than commonly observed region encompassing NSD1 by comparative genomic hybridization to DNA microarrays. 3) He had no mutation in the 5q35 region in the non-deleted chromosome using exsome sequence analysis. In conclusion, our patient supported that HIH could be one of the characteristic symptoms of SoS in the neonatal period, and could be useful for early diagnosis.