Chondrocytes from the cartilage proteoglycan-deficient mutant, nanomelia, synthesize greatly reduced levels of the proteoglycan core protein transcript.

Nanomelia is an avian mutation that results in the absence of the major proteoglycan of cartilage. The deficiency in mutant chondrocytes results from their failure to express the cartilage proteoglycan core protein. Using cartilage proteoglycan core protein cDNA probes, the present study shows that nanomelic chondrocytes synthesize greatly reduced levels of this core protein mRNA. The transcript is normal in size and, in addition, comparative analyses of normal and nanomelic genomic DNA show no indication of a major deletion of the core protein gene. These results are interpreted to mean that the mutation affects the regulation of transcription of the cartilage proteoglycan core protein gene.