Prateek Yadav, son of late SP founder Mulayam Yadav, had history of deep vein thrombosis - blood clots in veins, usually in legs and was at high risk medically, family doctor said. Ruchita Sharma said she advised Prateek to undergo thrombolysis, emergency procedure to break down blood clots to restore blood flow, but he refused. Prateek passed away at 38.