There has been speculation that Austen was poisoned (perhaps unintentionally) by arsenic or other heavy metals.   Arsenic was used in paint, for example, and so exposure was common.

Based on the alternative diagnosis of Addison's Disease (adrenal gland disorder), the fact she suffered from cataracts, and also her death at a relatively young age, my guess would be vitamin b12 deficiency was the underlying problem -- possibly, but not necessarily, pernicious anemia.    Also, pictures of her often indicate very high colouring -- another telltale sign for some (but not all) people with a genetic predisposition to problems metabolizing b12 or pernicious anemia.