FERMT3 and osteopetrosis: Also, we confirmed that the exonic sequences of all genes known to cause osteopetrosis or high bone mass contained no low-frequency variants that might contribute to the phenotype, with the exception of an amino-acid substitution Arg215Gln in FERMT3 [25], the gene-encoding Kindlin-3, an integrin-binding protein shown to be important in forming the sealing zone in a bone-resorbing osteoclast [26].