FAT4 and paroxysmal nocturnal hemoglobinuria: In addition to classical PNH, multiple chromosomal abnormalities as well as variants affecting 9 genes (ARF1, ARFGEF2, DCHS1, ERMARD, FAT4, INTS8, MAP1B, MCPH1, and NEDD4L) have been linked to PNH, indicating the genetic heterogeneity of the disorder [5–13].