The Republican push to replace the Affordable Care Act, also known as Obamacare, has raised special concern among one group of Americans - those with pre-existing conditions.

In insurance language, that means diseases, injuries or conditions that affected a patient before he or she got a health insurance policy.

Obamacare banned insurers from charging risk premiums based on pre-existing conditions. Before the law, people with such conditions could be denied health insurance coverage, or be charged very high premiums.

This could be about to change, as the American Health Care Act bill is headed to the Senate.

After the House of Representatives narrowly passed the bill, people took to Twitter to talk about their pre-existing conditions and fears of losing health coverage.

Diagnosed w/breast cancer at age of 44. I paid 6,500 ded, insurance billed 170k+, paid 70K. Paid 4,800 in premium. #IAmAPreExistingCondition — Sondra (@BucIGrl) May 4, 2017

I survived breast cancer once, currently fighting it again at 36, I fear 4 my future, but mostly 4 others w/worse #IAmAPreexistingCondition — Sarah DeJarlais (@SBDJ2381) May 4, 2017

One controversial part of the Republican-drafted bill is the "MacArthur amendment", which would give states the chance to seek a waiver from the requirement that insurers charge customers with pre-existing conditions the same as those without.

As compensation, a pool of money would be set aside to help people with pre-existing conditions afford coverage - but critics say that amount is far from enough.

"The bill allows insurance companies to refuse to cover those with pre-existing conditions, or charge them more for coverage, meaning that conditions ranging from asthma to pregnancy to cystic fibrosis could completely devastate a family financially and leave those who need care unable to access it," the American Academy of Pediatrics said.

My son, day 3 of life & now, who has mild cerebral palsy, asthma & uses special education services at school. #IAmAPreexistingCondition pic.twitter.com/bdCXlZfhRW — Ashley Sager (@ashleysager81) May 4, 2017

Some social media users were angered by Republican Alabama Congressman Mo Brooks' comments implying that people with pre-existing conditions simply are not living their lives "the right way".

30 y/o,doesn't smoke,exercises 5-7 days a week,but was born with Crohns Disease.But I'm not living "the right way" #IAmAPreexistingCondition — Todd DeSando (@MrDeSando) May 4, 2017

I survived a heart transplant and live with PTSD. #IAmAPreexistingCondition — Faith Nieting (@faith_anne) May 4, 2017

I've had asthma since I'm 7 months old. Must be because I wasn't living a "good life" for the first 6. #IAmAPreexistingCondition — WEB (@WeeumBasha) May 4, 2017