If my sister has mthfr could i??

my sister has mthfr...its a gene disorder or something. it causes miscarriages, abruptions during pregnancy, preclampsia, and birth defects including downs syndrome and spinal bifida. i think its somewhat common....but does anyone know if its hereditary or if i have a higher chance of having it? i've looked it up online but it seems really complicated. i have one child....i had an easy pregnancy and he is okay. but, then again my sister has two children with no complications as well. (but she had a hard pregnancy, with abruptions and preclampsia and she had many miscarriages). thanks for your help.