The CSF1R gene is consistently lost by partial deletions occurring in chromosome 5 in patients with Myelodysplastic syndrome (MDS)1. Specific deletion of the CSFS1R gene has been detected in as many as 40% of MDS patients. Studies have also shown that up to 58% of all breast carcinomas and 85% of invasive breast carcinomas express higher levels of CSF1R compared to normal resting breast tissue2,3. There also seems to be evidence to suggest that the expression of CSF1R in cervical cancer is usually associated with a more aggressive and invasive disease4. EGR aids in this diagnosis by helping determine whether there is a complete loss of chromosome 5 versus a 5q deletion (5q-) present in MDS5.