Coats and his identical twin, Devin, of Slidell, Louisiana, were both diagnosed with a severe form of liver cirrhosis in March 2017. The cirrhosis was thought to be caused by a rare genetic mutation shared by the brothers, their mother said.
"It was not his fault, but ultimately, he paid the price because of it," said Margi Coats, the boys' mother. "My son had big aspirations for life. He wanted to go to Texas A&M to go to engineering school. He was smart.
"Now, his life is cut short because of the lack of donors," she believes, "and with the millions of people we have in this country, there's no sense in it."
Devin was able to receive a liver transplant this year. However, Nick was deemed ineligible for a transplant at the time because his liver was not damaged enough to place him on the donor registry, Coats said.
While waiting for his liver condition to worsen, Nick developed angiosarcoma, an aggressive cancer of the blood vessels that probably originated in his damaged liver, his mother said.
A match for Nick was found in February, but by that point, it was too late. Doctors would no longer proceed with the transplant due to the metastasized cancer, his mother said. Had the pool of available donors been larger, he may have been eligible for a transplant in time to save his life, she believes.
"From what I understand, they cannot give organs to somebody that's already fighting another disease. They want it to go to a healthy person," she added.
"So with his cancer, that kind of put him on the back burner."
Nick died surrounded by his family and loved ones. His funeral is set for Wednesday.
"Nick requested to be placed outside by a garden in nature, and we have secured a place. It's a beautiful area, and I know that he would enjoy it," their mother said.
After Nick's deaths, hundreds of people from across the country posted on the family's Facebook
pages to offer their condolences.
"I am so sorry, I pray for people to get on board and sign up for organ donation. God Bless you and your family. I know being on the list, getting on the list is hard. Waiting is hard. But to do it for two is unfair," one post said.
"My niece ... is 22 years old and my sister's only child. She has been waiting for a liver transplant as well," another person posted.
Nick's death has inspired his mother to educate people -- especially teenagers -- about the societal benefits of becoming an organ donor.
"This could be you one day. This could be you needing a kidney; this could be you needing a heart," she said. "Now I have a cause, I have a meaning, and it's something strong that I feel in my heart."
Those interested in registering can sign up at organdonor.gov
More than 90% of Americans support organ donation, but just over 50% are signed up in the organ registry, according to Anne Paschke, public relations manager for the United States nonprofit United Network for Organ Sharing
According to the US Department of Health and Human Services
, there are 114,951 candidates on organ transplant waiting lists in the United States. Of these, 83% are waiting for a kidney, 12% for a liver and 4% for a heart.
"The good news is that we had a record number of donors and transplants last year. About 95 people a day got a transplant," Paschke said. "But that's not enough. About 20 people die [per day] waiting for an organ that doesn't come in time."
Before his death, Nick asked that his body be used to help others like him.
"We were able to donate the cornea of his eyes, which I felt was a blessing," his mother said. "I feel like now Nick continues to live; he's just living through the eyes of someone else."
The experience also reminded Nick's mother of one of her favorite quotes, which she says has given her strength over the past few weeks: " 'You can't take your organs to heaven, because heaven knows you need them here.'
"I think that's a beautiful ending to this whole situation," she added. "Don't let anything go to waste."