The IGH gene is located on chromosome 14q32.33. The IGH Break Apart FISH probe is designed to label both ends of the IGH gene, respectively. A 300 Kb orange probe is designed at the 3′ end of the IGH gene, and an 850 Kb green probe is designed at the 5′ end of the IGH gene.

IGH gene breaks and translocations are complex, involving multiple genes, commonly found in ALL/MM/lymphomas. In ALL, IGH-MYC reciprocal translocations have the highest frequency. IGH translocations with other genes are also common in both T-ALL and B-ALL.