G6PC1 and obesity due to melanocortin 4 receptor deficiency: Of interest, when the 60–90 week-old AAV-G6pc−/− mice that expressed 1%–63% of normal hepatic G6Pase-α activity were compared to age-matched WT mice, the AAV-G6pc−/− mice were protected against age-related obesity and insulin resistance that occur in WT mice (Kim et al., 2015; Kim et al., 2017b).