Pleural effusion was observed in two females aged 23 and 40 years: thoracentesis revealed cell counts of 720 and 450 with lymphocyte percentages of 80% and 98%, pleural fluid protein 2 g and 2.2 g, fluid LDH/serum LDH values of 468/691[67%] and 527/1000[52.7%] and ADA values of 28 U and 76 U respectively. The gene discussed is ADA; the disease is Pleural effusion.