When your body experiences Vitamin B 12 deficiency and the rise in Homocysteine levels, you might suffer from Pernicious Anaemia. This is a disease where your body is incapable of absorbing Vitamin B12 from the gut. It takes years for the first symptoms to even appear and these symptoms are; clumsiness, lack of coordination, and change in personality. With the help of this test, your doctor will be able to provide a thorough diagnosis. What is homocysteine? It is nothing but amino acid. The levels of homocysteine increase because of metabolism to cysteine of methionine to cysteine is damaged.