Breathe in and straighten your back: hypoxia, notch, and scoliosis.

In this issue of Cell, Sparrow et al. propose a new mechanism for sporadically occurring congenital scoliosis in which Notch signaling and hypoxia converge in the embryo on somite patterning via the segmentation clock. This interaction between hypoxia and a predisposed genetic background might underlie other birth defects with incomplete penetrance.