REFINEMENT OF THE X-LINKED CLEFT-PALATE AND ANKYLOGLOSSIA (CPX) LOCALIZATION BY GENETIC-MAPPING IN AN ICELANDIC KINDRED

The gene responsible for X-linked cleft palate and ankyloglossia (CPX) has previously been localized to the proximal region of the q arm of the X chromosome in both Icelandic and North American Indian kindreds. In this study, further linkage analysis has been performed on the Ice landic family and has resulted in a significant reduction in the size of the interval containing the mutated gene. A new polymorphism at DXS 95, together with DXS 1002 and DXS349, defines the proximal boundary o f the CPX interval, whereas DXYS1X defines the distal boundary. Multip oint analysis supports this localisation with a peak lod score of 12.7 , more than 2 lod score units higher than the next most likely positio n. In order to assess the physical size of the CPX interval prior to i nitiating yeast artificial chromosome cloning, metaphase fluorescence in situ hybridisation analysis was performed with the closest flanking markers. The size of the interval between DXS95 and DXYS1X was estima ted to be approximately 2-3 Mb.