Differential Alu PCR fingerprint cloning was used to isolate a DNA probe from the Xp 11.4→p11.21 region of the human X chromosome. This novel sequence, cpXr318 (DXS742), detects a new submicroscopic deletion interval at the Norrie disease locus (NDP). Combining our data with the consensus genetic map of the proximal short arm of the X chromosome, we propose the physical order Xcen – DXS14 – DXS255 – (DXS426, TIMP) – (DXS742 – ([MAOB – MAOA -DXS7], NDP) – DXS77 – DXS228) – DXS209 – DXS148 -DXS196 – Xpter. The cpXr318 probe and a subclone from a cosmid corresponding to the DXS7 locus were converted into sequence-tagged sites. Finally, DXS742, DXS7, DXS77, and MAOA were integrated into a physical map spanning the Norrie disease locus.