Ossification gene found
Researchers led by Frederick Kaplan from the University of Pennsylvania in Philadelphia have identified a mutation that causes excessive bone growth in people with fibrodysplasia ossificans progressiva (FOP). By replacing a single base building block in a gene, the corresponding receptor appears to be more active. As a result, the bodies of those affected ossify from birth; Bone plates form even with the smallest of injuries.
FOP is one of the rarest diseases, with an estimated 2,500 people suffering from it worldwide. The scientists have examined 600 of them and their families for genetic markers over the past 15 years. They finally found what they were looking for on chromosome 2.
The point mutation in the gene for the activin receptor type 1A (ACVR1) causes the amino acid histidine to be incorporated at one point in the protein instead of the arginine originally occurring there. ACVR1 binds bone morphogenetic proteins (BMP), which regulate bone formation during embryonic development and later bone healing. The receptor influences the cell type into which stem cells mature.
Newborns with FOP initially only show characteristic deformations of the big toes. In the course of childhood, however, bone residues form throughout the body, which eventually block joints and increasingly paralyze those affected. So far there is no treatment option.
Kaplan and his colleagues are now trying to breed mice with the detected mutation in order to investigate therapeutic approaches on the animals. The scientists emphasize that their results are also important for research into a lack of bone growth, such as in osteoporosis.