MAOA and pachyonychia congenita: Cox regression analysis revealed that high MAOA expression was an adverse prognostic factor for both low-intermediate risk PC patients (hazard ratio [HR] 2.74, 95% confidence interval [CI] 1.26–5.92; P = 0.011) and high risk PC patients (HR 1.73, 95% CI 1.11–2.71; P = 0.016).