XPNPEP2 and ovarian dysfunction: The genes placed in the POF1 and POF2 loci of X chromosome are as follows:CHM (Xq21.1) (OMIM *300390), POF1B (Xq21.1)(OMIM *300603), DACH2 (Xq21.3) (OMIM *300608),DIAPH2 (Xq22) (OMIM *300108), NXF5 (Xq22.1)(OMIM *300319), COL4A6 (Xq22.3) (OMIM *303631),PGRMC1 (Xq24) (OMIM *300435), XPNPEP2 (Xq25)(OMIM *300145), FMR1 (Xq27.3) (OMIM *309550), andFMR2 (Xq28) (OMIM *300806).19, 20, 21, 22, 23, 24, 25, 26 However, despite the description of all these candidate genes, the cause ofpremature ovarian failure remains unknown in most cases.27,28