Balki's 'Paa' has Amitabh Bachchan and Abhishek Bachchan in a very different kind of a role. Unlike real life, the film portrays Amitabh Bachchan as Abhishek Bachchan's son. Amitabh Bachchan suffers from Progeria, a rare congenital abnormal characteristics where the person ages rapidly. Amitabh Bachchan is shown to have this rare characteristics in the film. The film is more an emotional father-son relationship with the ailment as the back-drop.