Serum ATX levels are reported to be elevated in subjects with chronic liver diseases, especially HCV hepatitis [27], various types of cancers [33–35], pregnancy [28], Graves’ disease [23], rheumatoid arthritis [21,22] and lung diseases [25,6]; furthermore, steroids also known to reduce the serum ATX levels [32], besides a malnutrition state [36]. This evidence concerns the gene ENPP2 and rheumatoid arthritis.