What has helped to drive research into their endogenous roles is that both receptors are associated with recessive autosomal diseases: mutations in CMG2 lead to hyaline fibromatosis syndrome (HFS), whereas mutations in TEM8 result in growth retardation, alopecia, pseudo-anodontia, and optic atrophy (GAPO) syndrome5–7. This evidence concerns the gene ANTXR2 and optic atrophy.