The glycerophosphodiester phosphodiesterase domain containing 5 (GDPD5), which encodes for the enzyme glycerophosphocholine phosphodiesterase that catalyzes the degradation of GPC to free choline (Figure 4) has been found to be positively correlated with PCho, tCho and PCho/GPC levels in human breast tumors [87]. The gene discussed is GDPD5; the disease is breast neoplasm.