Sir

The philosophical issues involved in privacy of genetic data are debated in your Editorial 'My genome. So what?' (Nature 456, 1; 2008) and in Patrick Taylor's Commentary 'When consent gets in the way' (Nature 456, 32–33; 2008). But practical concerns are an issue too.

Hospitals increasingly often have electronic databases accessible by all doctors and nurses on the staff and some administrators. Someone who had had an abortion, for example, could find this information available to thousands. Privacy is likewise denied to cancer patients who don't want their illness to be common knowledge.

Penalties for snooping are hard to enforce. Medical information sneaks out, particularly about celebrities: anyone in medicine can find out exactly what type of pancreatic tumour afflicted Steve Jobs of Apple, as well as the details of his operation.

The FBI is currently investigating a criminal network allegedly trying to extort money from patients who used a medical-benefits management company called Express Scripts; the company's computer records were, apparently, pilfered. People receiving medication for conditions such as herpesvirus were targeted.

Adding genetic information that can be interpreted in different ways will simply increase the exposure of patients to a system that is already faulty in practice.