Cartilage-hair hypoplasia gene assigned to chromosome 9 by linkage analysis.

Cartilage-hair hypoplasia (CHH) is an autosomal recessive skeletal dysplasia of unknown pathogenesis leading to short-limbed stature. Associated features include hypoplasia of hair, abnormal cellular immunity, deficient erythrogenesis, increased risk of malignancies, Hirschsprung disease, and Diamond-Blackfan type hypoplastic anaemia. We mapped the CHH gene by linkage analysis with 5 markers to chromosome 9. Multipoint linkage analysis gives a lod score of 9.94 for a location between D9S43 and D9S50. Based on strong linkage disequilibrium the closest marker, D9S50, is likely to be less than 1 cM from the gene. No heterogeneity was observed in 14 Finnish families, nor was there evidence of reduced penetrance. These results provide a starting point for the eventual cloning and characterization of the CHH gene.