NOTUM and dentin dysplasia: We previously described dentin dysplasia and incomplete pre-weaning lethality (32%, N = 3 391) in Notum−/− mice.30 Since 26% of surviving Notum−/− mice examined (N = 89) had unilateral kidney agenesis30 and WNT signaling is critical during kidney development,31,32 we suspect lethality results from bilateral kidney agenesis.