Yeah (his mom) is dead I'm not sure how but he mentioned a few times that she killed herself so maybe he was able to get money for the treatment and she killed herself after that or something but I'm not too sure
oh wait i just realized you meant Ming's sister.. I dont think shes dead because he would probably be a lot more upset but she might be and he might just be in denial or something
IS THE SISTER DEAD OR WHAT WTF IS GOING ON