In support of the key involvement of OSTM1 in LRRK1 signal pathways are the findings that both OSTM1 and CLC7 play a critical role in regulating osteoclast function by providing extracellular acidification and ablation of either Ostm1 or Clc7 in mice, causing severe osteopetrosis [19]. The gene discussed is OSTM1; the disease is osteopetrosis.