The PAX7 Breakapart probe consists of a green 109kb probe and a red 139kb probe, which are positioned on each side of the PAX7 gene.
Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in children. One of the primary histological subtypes is the alveolar RMS (ARMS)1.
The majority (55%) of ARMS are associated with the t(2;13)(q36.1;q14) translocation, and less commonly (22%) with t(1;13)(p36;q14), leading to the fusion of transcription factor FOXO1 (Forkhead Box protein 1) to the transcription factors PAX3 (Paired Box protein 3) and PAX7, respectively2. The distinction between the t(1;13) and t(2;13) in ARMS is important as patients with the t(2;13) have a more adverse outcome than those with the t(1;13)3.
In ARMS cases that are negative for translocations involving FOXO1, there are two other variant PAX3 translocations that could be present - t(X;2)(q13;q36.1) PAX3-FOXO44 and t(2;2)(q36.1;p23) PAX3-NCOA15.