In the hours following the passage of the American Health Care Act (AHCA) in the U.S. House of Representatives on May 4, thousands took to Twitter with the hashtag #IAmAPreexistingCondition.

People who have “preexisting conditions” as defined under pre-Affordable Care Act (ACA) policies fear they could lose coverage or see medical costs surge if the AHCA passes through the Senate.

According to research from the Henry J. Kaiser Family Foundation, up to 27 percent of Americans under the age of 65 — that’s over 52 million people — suffer from a preexisting condition that would allow insurance companies to decline coverage under the pre-ACA insurance market. (The ACA prevents insurance companies from refusing coverage or overcharging you due to a preexisting condition.)

What qualifies as a preexisting condition depends on the insurer. But a repeal of the ACA could give states and insurers the ability to deny coverage or offer hiked premiums to people with conditions such as multiple sclerosis, diabetes, arthritis, Crohn’s disease, lupus, epilepsy, bipolar disorder, and anxiety, among others.

Kaiser also lists pregnancy and transsexualism as preexisting conditions that could lead to declined coverage. Rape, sexual assault, postpartum depression, and “sexual deviation” may be potential others.

Here are just some of the people — including celebrities like Anna Paquin and Alyssa Milano — sharing their stories, and worries, with the #IAmAPreexistingCondition hashtag: