ATP6V1H and osteoporosis: We describe the consequences of atp6v1h mutation in zebrafish, based upon the ascertainment of a family with 3 generations of osteoporosis segregating with a K386N/N387Y mutation in ATP6V1H. We discovered a profound reduction in the amount of mature bone in homozygous atp6v1h zebrafish mutants; cartilage formation was largely unaffected.