Strain-specific hyperkyphosis and megaesophagus in Add1 null mice.

The three adducin proteins (α, β, and γ) share extensive sequence, structural, and functional homology. Heterodimers of α- and β-adducin are vital components of the red cell membrane skeleton, which is required to maintain red cell elasticity and structural integrity. In addition to anemia, targeted deletion of the α-adducin gene (Add1) reveals unexpected, strain-dependent non-erythroid phenotypes. On an inbred 129 genetic background, Add1 null mice show abnormal inward curvature of the cervicothoracic spine with complete penetrance. More surprisingly, a subset of 129-Add1 null mice develop severe megaesophagus, while examination of peripheral nerves reveals a reduced number of axons in 129-Add1 null mice at four months of age. These unforeseen phenotypes, described here, reveal new functions for adducin and provide new models of mammalian disease.