7p and 5qter

Evidence for linkage has been sought, in four pedigrees with Crouzon syndrome, between polymorphic markers known to be linked to the Saethre-Chotzen locus on 7p and another form of autosomal dominant craniosynostosis on 5q. The data we present exclude Crouzon syndrome as an allelic variant at either of these known craniosynostosis loci. (J7 Med Genet 1994;31:219-221) Mothercare Unit of Genetics and Fetal Medicine, Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK W Reardon R M Winter Molecular Genetics Unit, Institute of Child Health, 30 Guilford Street, London WCIH 1EH, UK L van Herwerden C Rose S Malcolm Department of Plastic and Reconstructive Surgery, The Hospital for Sick Children, Great Ormond Street, London WC1N 3JH, UK B Jones Correspondence to Dr Reardon. Received 1 September 1993 Accepted for publication 1 October 1993 The craniosynostoses comprise a clinically and genetically heterogeneous group of disorders characterised by premature fusion of the skull bone sutures. Several recognisable entities are identifiable within this broad group, among them Crouzon, Apert, Pfeiffer, and JacksonWeiss syndromes.' Originally described by Crouzon in a mother and son in 1912,2 the syndrome which bears his name (MIM No 123500) is principally characterised by craniosynostosis, shallow orbits, ocular proptosis, and maxillary hypoplasia, although a host of other clinical features have been identified.34 Although variability in gene expression within families is well documented, and indeed craniosynostosis has occasionally been absent in obligate gene carriers, the phenotype of the disorder is usually readily recognisable and the autosomal dominant mode of transmission is not in doubt.7 While Crouzon syndrome is clinically distinct from other autosomal dominant craniosynostosis syndromes, the aetiological relationship between these disorders remains unclear. Two such conditions have recently been mapped, the locus for Saethre-Chotzen syndrome being localised by mapping and cytogenetic evidence to 7p21"'0 and a family with autosomal dominant craniosynostosis of possibly undescribed type being assigned to 5qter using linked