Amends the Illinois Insurance Code to require an insurance policy to provide coverage for medically necessary treatments for genetic, rare, unknown or unnamed, and unique conditions, including Ehlers-Danlos syndrome and altered drug metabolism. Provides that an insurance policy that provides coverage for prescription drugs shall include coverage for opioid alternatives, coverage for medicines included in the Model List of Essential Medicines published by the World Health Organization, and coverage for custom-made medications and medical food. Provides that an insurance policy that limits the quantity of a medication in accordance with applicable State and federal law shall not require pre-approval for the treatment of patients with rare metabolism conditions that may need a higher dose of medication than what is otherwise allowed within a time frame or prescription schedule. Provides that the burden of proving that treatment is medically necessary shall not lie with the insured in cases of rejections for filing claims, preauthorization requests, and appeals related to coverage required under the Section.