5 C.F.R. § 339.206
An employee or applicant may not be disqualified for any position solely on the basis of medical history. For positions subject to medical standards and/or physical requirements, and for positions under medical evaluation programs, a history of a particular medical condition may result in medical disqualification only if the condition at issue is itself disqualifying, recurrence of the condition is based on reasonable medical judgment, and the duties of the position are such that a recurrence of the condition would pose a significant risk of substantial harm to the health and safety of the applicant or employee or others that cannot be eliminated or reduced by reasonable accommodation or any other agency efforts to mitigate risk.
5 C.F.R. §339.206