Detection of a Cryptic KMT2A/AFDN Gene Fusion [ins(6;11)(q27;q23q23)] in a Pediatric Patient with Newly Diagnosed Acute Myeloid Leukemia

KMT2A gene rearrangements are a major oncogenic driver in multiple hematologic neoplasms. Apart from t(9;11)(p21;q23) (KMT2A/MLLT3) in acute myeloid leukemia (AML), KMT2A gene rearrangements are considered to convey high risk and poor overall survival. Herein, we report a case of a 7 year old boy with newly diagnosed AML and a cryptic KMT2A/AFDN gene fusion resulting from a 5′KMT2A insertional event. The results of conventional chromosome studies revealed trisomy 8 in all 20 metaphases, with normal-appearing chromosomes 6 and 11. A KMT2A break-apart FISH probe identified 2 intact copies of the KMT2A gene region and an extra 5′KMT2A signal in 85% of interphase nuclei. in the literature that a cryptic KMT2A/AFDN gene fusion resulting from a 5′KMT2A insertional event was reported.