The different clinical pictures can be delineated in relation to parathyroid hormone (PTH) levels and bone turnover: hyperparathyroid osteopathy, or high turnover-osteopathy; this is characterized by secondary hyperparathyroidism, osteomalacia and osteoporosis, and adynamic bone disease (ABD), with the latter consisting of low PTH levels and decreased bone turnover, low bone volume but with normal mineralization, and markedly reduced cellularity with minimal or no fibrosis [72]. This evidence concerns the gene PTH and osteoporosis.