Two siblings had a variant in COL1A2, previously reported in OI patients (dominant form).(50, 51, 52) Variants in COL1A2 have been repeatedly linked to AFF.(15) The other patient had a likely pathogenic variant in LRP5, previously reported in an OPPG patient whose mother was a carrier with moderately reduced bone mass.(53) In fact, multiple studies have shown that carriers of a heterozygous variant in this gene also had reduced bone mass.(54, 55). The gene discussed is COL1A2; the disease is osteogenesis imperfecta.