We report a family with inherited Potocki–Shaffer syndrome. The phenotypically normal mother has an interstitial deletion of 11(p11.12p11.2) with neocentric marker chromosome formation. The marker chromosome contains the deleted material on 11p11.2 and is likely a ring. The patient inherited a maternal deleted chromosome 11 but not the marker chromosome, thus resulting in an unbalanced karyotype along with the phenotype of Potocki–Shaffer syndrome. The deleted region in our case—11p11.12p11.2—is a newly reported site of constitutional neocentromere formation. This is also the first report describing deletion of 11p11.12-p11.2 and neocentromere formation resulting in inherited Potocki–Shaffer syndrome. © 2005 Wiley-Liss, Inc.