A new analysis suggests that 52 million Americans could be denied health insurance if the Affordable Care Act is repealed.

The analysis done by the Kaiser Family Foundation relies on the fact that one in four non-elderly adults in the U.S. has a medical condition that could lead an insurer to deny them coverage if the ACA, which prohibits insurers from denying coverage based on pre-existing conditions.

The report’s authors note many of the 52 million people are currently covered by an employer-based health plan or Medicaid. Therefore, the report is not predicting that that many people would be without coverage, but that roughly a quarter of the U.S. population would be unable to buy insurance in the individual market if necessary.