L1CAM and cyclic hematopoiesis: Among them, only 4 genes have been confirmed to be linked to CH: two X-linked genes [L1CAM (L1 cell adhesion molecule) and AP1S2 (adaptor-related protein complex 1 subunit sigma 2)] and two autosomal recessive genes [MPDZ (multiple PDZ domain crumbs cell polarity complex component) and CCDC88C (coiled-coil domain containing 88C)].