Hi Ricky,
Welcome to the forum. I'm sorry to hear about your illness. S50N denotes a rare mutation in the TTR gene. Hereditary ATTR amyloidosis can be triggered by more than 100 different mutations in the TTR gene, and there is less information available about the rarer mutations.
Do you know if your doctor has referred you to the National Amyloidosis Centre in the Royal Free Hospital, London? If not, you should ask to be referred.