EVIDENCE FOR LOCUS HETEROGENEITY IN ACROCEPHALOSYNDACTYLY - A REFINEDLOCALIZATION FOR THE SAETHRE-CHOTZEN SYNDROME LOCUS ON DISTAL CHROMOSOME 7P - AND EXCLUSION OF JACKSON-WEISS SYNDROME FROM CRANIOSYNOSTOSISLOCI ON 7P AND 5Q

Craniosynostosis (premature fusion of the skull sutures) occurs as a c linically heterogeneous group of disorders, frequently involving digit al abnormalities. We have previously provisionally assigned the gene f or one such condition, Saethre-Chotzen syndrome (ACS III), to chromoso me 7p. Linkage analysis is now reported between ACS III and dinucleoti de repeat loci on distal 7p. The maximum lod scores, Z(max), were 5.57 at a recombination fraction of .05, with D7S488, and 4.74 at a recomb ination fraction of .05, with D7S493. Only weak linkage, not reaching significance, was found with distal markers (D7S513 and afm281vc9) and a proximal marker (D7S516). Multipoint analysis shows that the diseas e locus lies between D7S513 and D7S516. Analysis of individual recombi nants shows that the most likely position is between D7S493 and D7S516 . Linkage data in regard of Jackson-Weiss syndrome demonstrate that th is autosomal dominant form of acrocephalosyndactyly does not map to th e ACS III region on 7p or to the acrocephalosyndactyly locus on 5q (Bo ston type). These findings underline the genetic heterogeneity among t he different clinical conditions manifesting with acrocephalosyndactyl y.