Depending on the site of the break, three protein isoforms are distinguished: a variant with a molecular weight of 185–190 kDa (p190), commonly found in ALL; a variant with a mass of 210 kDa (p210), prevalent in chronic myeloid leukemia (CML); and the rarest variant, with the highest molecular weight of 230 kDa (p230) [87]. The gene discussed is CNTNAP1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.