HoLEP vs. TURP Greater decrease in Hb levels after HoLEP (p<0.001) Median sodium decrease (− 1 vs. −1mEq/L) Repeat bladder outlet surgery (1 vs. 1) Visible hematuria requiring intervention (2 vs. 4) Urethral stricture requiring intervention (3 vs. 3) Persistent retention requiring intermittent self-catheterization (1 vs. 10). The gene discussed is GSTM1; the disease is urinary system disorder.