Exclusion of human proteoglycan link protein (CRTL1) and type II collagen (COL2A1) genes in pseudoachondroplasia

Patients with pseudoachondroplasia have a skeletal dysplasia with marked short stature. The most common cause of this condition is an autosomal dominant mutation, although autosomal recessive inheritance has been reported. Linkage to 2 cartilage-specific candidate genes, type II collagen (COL2A1) and proteoglycan link protein genes (CRTL1), was tested in 9 autosomal dominant families with pseudoachondroplasia. Tight linkage to these candidate genes was excluded with LOD scores for COL2A1 of -2.45 at θ = 0.05 and for CRTL1 of -7.28 at θ = 0.001. Discordant inheritance of the disease phenotype with each of these genes was also observed. Thus, these 2 candidate genes can be excluded as the cause of disease in these families.