A 25-year-old man with ALL has a Philadelphia chromosome. Compared with CML, the BCR-ABL1 fusion in Ph+ ALL most commonly produces a protein of:

• A p210 (same as CML, major breakpoint cluster region)
• B p230 (micro BCR breakpoint, seen in CML with neutrophilia)
• C p190 (minor BCR breakpoint, with stronger kinase activity) ✓
• D p185 (from an alternative splice form of ABL1)

Explanation

Ph+ B-ALL most commonly produces the p190 (BCR-ABL1) fusion protein arising from a minor breakpoint cluster region (m-BCR, e1a2 junction), which has more potent tyrosine kinase activity than p210. CML and approximately one-third of Ph+ adult ALL produce the p210 protein (major BCR, b2a2 or b3a2 junction). p230 (micro-BCR) is associated with chronic neutrophilic leukemia. The distinction matters because p190 ALL has unique biology and treatment implications.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.