When patients were divided by severity of HS and the presence/absence of UDT, median value of serum FSH was 3.8 mIU/ml in patients with mild HS without UDT (n = 33), 5.4 in patients with severe HS without UDT (n = 34), 2.4 in patients with mild HS and UDT (n = 2), or 12.4 in patients with severe HS and UDT (n = 10), respectively. The gene discussed is BRD2; the disease is histiocytic sarcoma.