In epilepsies arising from a genetic cause, analyses of the genetic etiology have occasionally found causal loss-of-function mutations in inhibitory conductances 10; however, loss-of-function.

The cause is usually a deficiency of either cobalamin (vitamin B 12) or folate, but megaloblastic anemia may occur because of genetic or acquired abnormalities that affect the metabolism of these vitamins or because of defects in DNA synthesis not related to cobalamin or folate . Cobalamin and folate absorption and metabolism are described next.