Formate rescues neural tube defects caused by mutations in <i>Slc25a32</i>

Abstract

Periconceptional folic acid (FA) supplementation significantly reduces the prevalence of neural tube defects (NTDs). Unfortunately, some NTDs are FA resistant, and as such, NTDs remain a global public health concern. Previous studies have identified SLC25A32 as a mitochondrial folate transporter (MFT), which is capable of transferring tetrahydrofolate (THF) from cellular cytoplasm to the mitochondria in vitro. Herein, we show that gene trap inactivation of <i>Slc25a32</i> (<i>Mft</i>) in mice induces NTDs that are folate (5-methyltetrahydrofolate, 5-mTHF) resistant yet are preventable by formate supplementation. <i>Slc25a32</i>^<i>gt/gt</i> embryos die in utero with 100% penetrant cranial NTDs. 5-mTHF supplementation failed to promote normal neural tube closure (NTC) in mutant embryos, while formate supplementation enabled the majority (78%) of knockout embryos to complete NTC. A parallel genetic study in human subjects with NTDs identified biallelic loss of function <i>SLC25A32</i> variants in a cranial NTD case. These data demonstrate that the loss of functional <i>Slc25a32</i> results in cranial NTDs in mice and has also been observed in a human NTD patient.