Thirdly, the family Lachnospiraceae has been reported to facilitate Treg differentiation and stimulate TGF-β and IL-10 production by immune cells.(12) TGF-β is a key molecule in the pathogenesis of CARASIL, an autosomal recessive small vessel disease caused by HTRA1 mutations.(13) Dysregulation of TGF-β signaling may also be associated with CADASIL according to a report that latent TGF-β binding protein 1 was sequestrated into CADASIL-related NOTCH3 extracellular domain deposits.(14) Taken together, the increase of Lachnospiraceae in CADASIL patients is of interest. Here, NOTCH3 is linked to CARASIL.