Process Patients are entered into DECIPHER by registered consortium members. Typically a clinical geneticist arranges for a chromosome analysis (usually microarray based) of a patient's DNA. A potential microdeletion/microduplication may be identified, but the medical significance is not known. The clinician may enter the anonymised data into the restricted, password protected DECIPHER database and map the location and size of the chromosomal deletion/duplication to the reference genome. Using DECIPHER, the clinician can then identify the specific genes affected by the deletion/duplication, determine whether any have known clinical significance (for example, whether tumour suppressor genes have been deleted), and view the region in the Ensembl genome browser to see whether there are any other consented patients in DECIPHER with overlapping deletion/duplications. This enables a better ascertainment of whether a copy number change is a normal polymorphic variant, or the likely cause of the patient's clinical symptoms. The clinician can then counsel the patient on the likely significance of the deletion/duplication, and its implications for their health. Each patient's data is anonymized, and represented only by an ID with an associated genotype and set of clinical symptoms (phenotypes). Patient data is made accessible to other members of the consortium and viewable through Ensembl if a consent form is signed by the patient. With informed consent, the anonymized deletion/duplication and phenotypes become available for view to DECIPHER consortium members and public users, with different levels of access (e.g. only logged users can see the contact details of the centre that entered the data). Public users who wish to find more information about a patient may send a request to DECIPHER, which then will forward it to the clinician coordinator responsible for the submitting center. Most patients deposited in DECIPHER display genetic mutations with a very low occurrence in the general population. Hence the probability of the same clinicians encountering similar patients are also low. Since DECIPHER is opened to any accredited clinician or cytogeneticist from around the world, the chances of finding similar rare cases are significantly increased. This on-line sharing of clinical genetic information not only promotes better understanding of microdeletions/microduplications and their associated pathogenic phenotypes, it has also facilitated the discovery of new syndromes. As of January 2014, over 23000 patients have been entered into the DECIPHER database of which over 10000 are consented. Ethics and privacy The appropriate consent to enter patient data into DECIPHER is obtained by the submitting