A consumer group has sued the health insurer Aetna, claiming that it discriminated against patients with HIV when it required them to obtain medications exclusively through its own mail-order pharmacy. The lawsuit, filed Friday in federal court in San Diego by the advocacy group Consumer Watchdog, argues that Aetna's policy violates the new federal health care law, which prohibits insurers from discriminating against people based on medical condition. The company's new policy, which takes effect Jan. 1 and applies to people who have purchased individual coverage, also raises the out-of-pocket amount that patients must pay for their treatments, potentially doubling it in some cases, according to the suit.