JF1/B6F1 Ngly1−/− mouse as an isogenic animal model of NGLY1 deficiency

N-Glycanase 1 (NGLY1) deficiency is a congenital disorder caused by mutations in the NGLY1 gene. Because systemic Ngly1^−/− mice with a C57BL/6 (B6) background are embryonically lethal, studies on the mechanism of NGLY1 deficiency using mice have been problematic. In this study, B6-Ngly1^−/+ mice were crossed with Japanese wild mice-originated Japanese fancy mouse 1 (JF1) mice to produce viable F₂ Ngly1^−/− mice from (JF1×B6)F₁ Ngly1^−/+ mice. Systemic Ngly1^−/− mice with a JF1 mouse background were also embryonically lethal. Hybrid F1 Ngly1^−/− (JF1/B6F1) mice, however, showed developmental delay and motor dysfunction, similar to that in human patients. JF1/B6F1 Ngly1^−/− mice showed increased levels of plasma and urinary aspartylglycosamine, a potential biomarker for NGLY1 deficiency. JF1/B6F1 Ngly1^−/− mice are a useful isogenic animal model for the preclinical testing of therapeutic options and understanding the precise pathogenic mechanisms responsible for NGLY1 deficiency.