Privacy and intra-familiy communication of genetic information

The new knowledge (and predictions) created by DNA tests and the family nature of genetic information has already lead to a new problem: the intra-familiar communication of genetic data. This raises questions such as the following. Is there a duty to inform in cases when treatment is possible and the patient does not permit disclosure of genetic results to relatives? Is there an obligation to warn or merely an authorization (that could be used or not)? Could privacy protection be maintain as an individual interest but with some justified violations? A balance needs to be establishes between the interest of privacy and the need to disclose secret information.