Pfeiffer syndrome (PS) Is an autosomal dominant disorder characterized by cranlosynostosis, mldfaclal hypoplasia, and broad thumbs and great toes. We examined 129 Individuals from 11 families with PS and performed linkage studies using microsatellite markers spanning the entire genome. Strongest support for linkage was with DNA markers (D8S255, GATA8G08) from chromosome 8. Obligate crossovers exclude close linkage to this region in six families, and there was significant evidence for genetic heterogeneity. A multipoint lod score of 7.15 was obtained In five families. The 11 cM Interval between D8S278 and D8S285 contains one gene for PS and also spans the centromere of chromosome 8. © 1994 Oxford University Press.