This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goals of this project are to define the defective genes responsible for the short-rib polydactyly syndromes and asphyxiating thoracic dystrophy. These are autosomal recessive, primarily perinatal lethal disorders that are hypothesized to be either allelic or are shared components of a pathway. Using family based, linkage analysis studies, and then positional candidate gene approaches, this proposal will identify the disease genes for these disorders. Identification of these genes should help define a novel pathway which leads to abnormal cartilage and bone.