The gene for autosomal recessive Robinow syndrome is located in 9q. H. Van Bokhoven¹, E. van Beusekom¹, J. Celli¹, H. Kayserili², H.G. Brunner¹. 1) Dept Human Genetics 417, University Hospital Nijmegen, Nijmegen, The Netherlands; 2) Division of Medical Genetics, University of Istanbul, Istanbul, Turkey.

   Robinow syndrome has hypertelorism, short stature, mesomelic shortening of the forearms and forelegs and hypoplastic genitalia as its most characteristic features. Both autosomal dominant and autosomal recessive forms exist. The genetic basis for Robinow syndrome is not yet known, but the phenotype of the autosomal recessive form suggests that the mutation may affect a gene that is involved in vertebral segmentation. We have used homozygosity mapping to localise the gene for autosomal recessive Robinow syndrome in five families of Turkish descent. Our results indicate that the Robinow syndrome gene is located in 9q21-q23 (Zmax = 5.72 at 'Q'=0). A Detailed analysis with markers spanning the 14cM critical region between D9S257 and D9S176 shows haplotype sharing between two of the families, which reduces the critical interval to 11cM between D9S1796 and D9S176. No obvious ancestral haplotype was present in this sample of five families. The results suggest that multiple mutant alleles at a single locus in 9q are involved in the high frequency of Robinow syndrome in Turkey.Q.