(a) A patient is eligible to access and use an investigational drug, biological product, or device, consistent with Texas Health and Safety Code §490.001, if:(1) the patient's treating physician confirms, in writing, the patient has a diagnosis of a severe chronic disease; and(2) the patient signs a written informed consent as described in §1.4 of this subchapter (relating to Informed Consent).(b) A treating physician must maintain the written confirmation of a patient's severe chronic disease diagnosis in the medical record of the treating physician in accordance with the applicable records retention requirements.