We report on.in infant boy \vitli congenital hydrocephatLis CILle to 1.1 syndrorne and p0lyUria dne to diabetes itisipidtis. We initially believed Ins excessive Lirine loss was froin central diabetes insipidLIS and diat the cerebral inalforniation caused a secondary insufficient pitnitary vasopressin release. However, lie failed to respond to treatnient with a vasopressin analOgLie, wliicli pointed to neplirogenic diabetes insipidus (NDI). LI syndrorne and X-linked NDI are distinct clinical disorders caLISed J-)y inutations in the LICAM and A'VTR2 genes, respectively, located in adjacent positions in Xq28. In this boy we foLind a deletion of 61,577 basepairs enconipassing the entire LlCAM and A 11711?2 genes and extending into introit 7 of the APJ-IGAI-'4 gene. To oLir knowledge this is the first description of a patient Nvitli a deletion of these diree genes. He is the second patient to be described with Ll syndrorne and NDL DUI-ing fOIIO\V-LIJ) lie inanifested cornplications front the hydroceplialLis and NI)l inClUding global developniental delay and gro, vtli faikire -,vith low IGF-I and liypotliyroidisni. (c) 2008 wile\'-Liss Inc.