Cat not eating , simply ignoring any food: Help wanted

Today I was approached by a customer from overseas. Her cat is not eating, period. For 10 months already! (Yes, I confirmed that to make sure there is no misunderstanding). She is looking at the food and then walks away. The owner has tried everything possible, pretty much every food available over there (which is actually a much better food and variety than what we have here available to us, but that does not mean they don’t face similar problems like we do) and including spending thousands of $ for vets and other specialists, all without any success. Currently she is force feeding the animal. I was just wondering if there is anybody out there with a similar experience who may be able to provide some input and advice. This is a first one for me and I would greatly appreciate any contribution on this topic.