Re: And as for how long...
>I expect they keep the records for six years
From memory, in the UK it is 30 years, which is laughable, as it meant my Dr could not refer to the details of various conditions, first diagnosed and treated in childhood.
Six years after the patient died, because a civil claim against the health authority will be out of time if not started before then. It is only three years if the claim is that the health authority injured the patient.
Remember health records are explicitly for the treatment of the patient, not for any other purpose like later research unless the patient consented. So you can't use them for DNA studies even if the patient is now dead.