Subsequent studies have been conflicting with some authors observing an independent association of the RFC-1 80A>G polymorphism with the maternal risk of DS in the offspring [20,21] or even more complex interactions among RFC-1 and other polymorphisms in genes involved in one-carbon metabolism [22,23,24], and others failing to find any association of RFC-1 80A>G alone or combined [25,26,27]. The gene discussed is RFC1; the disease is Dravet syndrome.