A transcriptional profile of human fetal cartilage

Cartilage plays a central role in the patterning and growth of the skeletal elements, and mutations in genes expressed in cartilage are responsible for at least 250 distinct clinical conditions, the osteochondrodysplasias. While recent progress has been made in characterizing the genes that define cartilage biology, there are only limited data describing the gene expression profile of human cartilage. Here we describe the sequences and identities of 6266 clones from an 18-20-week human fetal cartilage cDNA library. Among the sequences, BLAST analysis identified 2404 individual transcripts. Of these, 1775 were defined as derived from characterized genes and the remaining 629 were classified as representing the products of uncharacterized genes. Analysis of the relative representation of each individual transcript showed that the 186 most abundant cDNAs in the library accounted for almost half (47.7%) of the clones. The most highly expressed gene was COL2A1, accounting for 4.15% of all cDNA clones. The cDNAs identified included clones derived from 27 genes which, when mutated, result in disorders of skeletal patterning, development and growth. There were cDNAs representing 22 genes encoding collagen subunits. The genes encoding the identified cDNAs represent candidates for the approximately 100 osteochondrodysplasias for which the causative gene has not yet been identified. Moreover, these data provide an extensive profile of human fetal cartilage gene expression at this developmental stage.