In contrast to Axin1 cKO mice, deletion of Axin1 in Sox9-, Col2a1-, and Sp7-expressing cells does not affect fibular development (Figure 2K, Figure 2—source data 1), suggesting that FH disease is caused by defects in the specific cell population, limb mesenchymal cells. The gene discussed is SP7; the disease is familial hyperaldosteronism.