The objective of this study is to determine the molecular basis of craniosynostosis, Philadelphia type. Previous studies by our lab have excluded FGFR1, FGFR2 and FGFR3, the causative genes of most hereditary craniosynostosis syndromes. In the five generation kindred previously reported we have conducted a genome-wide linkage analysis. We have identified four regions linked to this disorder, namely on 2q, 12q, 20q and 22q. Interestingly, syndactyly 1A, a phenotypically similar disorder, demonstrates an overlapping linkage region in two studies. Screening of candidate genes in the redion has excluded ten candidate genes, including IHH, IGFBP2 and IGFBP5.