The present invention relates to systems, methods and 
software arrangements for the detection of variations in the copy number of a 
gene in a 
genome. These systems, methods and 
software arrangements are based on a simple prior model that uses a first process generating amplifications and deletions in the 
genome, and a second process modifying the 
signal obtained to account for the corrupting 
noise inherent in the technical methodology used to scan the 
genome. A Bayesian approach according to the present invention determines, e.g., the most plausible 
hypothesis of regional changes in the genome and their associated copy number. The systems, methods, and 
software arrangements can be are framed as optimization problems, in which a 
score function is minimized. The 
system, methods and software arrangements may be useful to assist the 
scientific study, diagnosis and / or treatment of any 
disease which has a genetic component, including but not limited to cancers and inherited diseases.