They can and do base eligibility on medical history, and they tend to have blanket exclusions for anything related to a pre-existing condition. (verywell.com)
You should avoid using blanket exclusion policies because they may trigger the kind of scrutiny from the EEOC you do not want. (proformascreening.com)
After the Delhi High Court's recent ruling, blanket exclusion of genetic disorders from coverage is likely to become a thing of the past (business-standard.com)