With U.S. House Republicans passing a bill this week to start repealing Obamacare, many Americans with ongoing health issues have been taking their panic and outrage to Twitter.

The American Health Care Act (AHCA), passed on Thursday, aims to undo many of the provisions of the Affordable Care Act (ACA), former U.S. president Barack Obama’s signature piece of health legislation.

Republicans say the 2010 law is an example of government overreach and argue their new bill will eventually give people more choice.

But those opposing the bill say the AHCA would leave many Americans with pre-existing health conditions at risk of having to pay higher health insurance premiums -- a common practice before Obamacare.

What constitutes a pre-existing condition under the AHCA? The list is lengthy and includes everything from cancer, to acne, to having had a C-section.

Twitter users began tweeting under the #IAmAPreexistingCondition hashtag, to list the conditions they had that would make it difficult for them to get affordable insurance coverage.

Here are some of the most popular: