MTHFS and hyperinsulinemic hypoglycemia, familial, 4: Considering the mechanism of the link between MTHFS deficiency and recurrent diarrhea, regeneration of the intestinal surface may depend on adequate folate status on the one hand, and may be related to the role of folate in innate and/or adaptive antigen-specific immune responses on the other (Dhur et al., 1991; Manger et al., 2011).