SMCHD1 and Kallmann syndrome: By identifying the relevant cell type (cranial placode) and mechanism of cell death (DUX4), Kaoru et al. proposed that in patients with arhinia and related nasal phenotypes (e.g., anosmia and nasal hypoplasia), nasal morphogenesis is completely or partially arrested when SMCHD1 missense mutations unleash DUX4 toxicity in cranial placode cells, leading to cell death [19].