- The paternal gene of the DDK syndrome maps to the Schlafen gene cluster on mouse chromosome 11. Bell, T.A., de la Casa-Esperón, E., Doherty, H.E., Ideraabdullah, F., Kim, K., Wang, Y., Lange, L.A., Wilhemsen, K., Lange, E.M., Sapienza, C., de Villena, F.P. Genetics (2006)