Illness stress-induced transient hyperglycemia in a patient with a novel YIPF5 homozygous missense variant: expanding the phenotype.

A recently described type of neonatal diabetes mellitus is caused by mutations in the YIPF5 gene and is combined with manifestations from the central nervous system, including developmental delay, epilepsy, and microcephaly. The molecular pathophysiology behind this phenotype involves the breakdown of the endoplasmic reticulum stress response due to the loss of protein folding capacity. This results in overt diabetes present from very early in life. Herein, we describe a patient with a newly reported variant in the YIPF5 gene, who presented with short events of severe hyperglycemia, induced by the stress of common illnesses, which completely resolved after recovery. We discuss the nature of transient hyperglycemia in the context of the YIPF5 gene variant and compare this phenotype with the previously described cases.