They also found novel CNVs in the genes previously implicated in bone metabolism, COL1A2 and PLS2. A 4-kb deletion of exons 1–4 in COL1A2 and a 12.5-kb duplication in exon 3 of the PLS3 gene were detected in patients with severe osteoporosis, confirming the monogenic nature of both genes in early-onset OP. The gene discussed is COL1A2; the disease is osteoporosis.