Hello, Cathy that is such a very sad story and my heart goes out to you. I noticed this question was asked a few years ago; I hope by now that time has helped you heal a little bit. Prader-Willi Syndrome, as you know, is a rare genetic abnormality that causes several of the problems your daughter had, including severe morbid obesity. Factor V (5) Leiden is a separate genetic condition that creates a defect in 1 of the multiple proteins involved in balancing the formation of blood clots and the dissolving of blood clots. Obesity and clotting protein abnormalities are both significant risk factors for development of deep venous thrombosis and pulmonary embolism. Your question is a very common one. What did dying feel like for my loved one? A pulmonary saddle thromboembolism that you refer to is the most gigantic of blood clots, which travels to the Main Pulmonary Artery, the largest of the vessels that leaves the right ventricle of the heart. The way it straddles the beginning of the Main Pulmonary Artery, right where it bifurcates (branches off) into the Right and Left Pulmonary Arteries to the beginning of each lung, makes it resemble a saddle that sits on a horse s back. Hence, the descriptive name. A clot that large in that vitally important strategic location usually causes sudden and acute severe shock, low blood pressure, and passing out, followed by a quick death. It s impossible to know for sure, but I will provide an educated guess that might (hopefully) give you some peace and comfort with this horrific situation. There might have been some shortness of breath and some chest pain, but most likely not for long before she would have passed out, fallen asleep, and not woken up. That would usually be a quick, not prolonged, passage to death. Lastly, I would advise you to seek counseling with a psychologist, a social worker, a clergy person, other friends and relatives, and/or a support group. Any of these professionals can be found who specialize in grief counseling. Google that term. Read up on grief and grieving and how people have coped and recovered with time. Since your Question was dated 4 years ago (and I just found it tonight), I hope you have done some of this by now. Losing a child, it is said, is the most painful grief and loss a person can go through. But, unfortunately, you are not alone in this experience. That is why grieving parents support groups, counselors, etc. are very helpful in helping people recover, since it reinforces the concept that you are not alone; others have walked your path. And, it can be cathartic just to hear a stranger tell a story that matches up with your own. I wish you peace and comfort, and please write us again and describe where you are now, and how you have kept your wonderful daughter s memory and legacy alive. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr. Robert I. Rattiner, M.D.