While graduation marks a coming of age for most high school students, the ceremony illustrates a legacy of perseverance for one Mount Vernon High School senior.

Delaney O’Hagan, 17, was diagnosed with leukemia in the second grade after her parents noticed she was extremely fatigued and pale, and bruised easily. After undergoing treatments, Delaney’s mother, Jami O’Hagan — an instructional assistant at Washington Mill Elementary School — said they were devastated by the news she had relapsed in sixth grade.

“We were completely blindsided. We came home from vacation, and she had no symptoms,” O’Hagan said, adding that a routine follow-up doctor’s appointment found Delaney had relapsed.

Since then, Delaney relapsed again as a freshman, causing her to miss most of the second part of the school year.

“My freshman year, I never came back [to school] after December. This year, I’ve missed 11 weeks,” she said.

“Throughout the years, I’ve had to take steroids and had several hundred spinal taps. Because of that I’ve built up scar tissue,” said Delaney, who began using a wheelchair again in January, because of impaired motor skills and fatigue.

She has been in and out of a wheelchair for 10 years. Delaney’s treatment throughout the years has included a weeklong round of radiation and five nonconsecutive years of chemotherapy treatments. During her freshman year, Delaney received a bone marrow transplant from her older brother, Grady, now 21, who attends Old Dominion University.

“We always say that I have two birthdays because I have my actual birthday, Sept. 14, and my re-birthday, March 10, when I got my bone marrow transplant,” Delaney said.

Although she is considered in remission, her medical woes are not yet over, she said. Possibly as a result of the bone marrow transplant, Delaney suffered two brain bleeds in July and January. As a result, she lost some memory skills, has some speech issues, lost some hearing in her right ear and wears a fogged right lens within her eyeglasses because of vision issues.

“Life has not been kind to her,” said Washington Mill Principal Tish Howard, who has watched Delaney grow up. “But she’s always got a smile on her face. . . . She’s the perfect example of why you don’t set odds. She’s a survivor. . . . Graduation is going to be a celebration of the ‘what if.’”

When her name is called during Mount Vernon High School’s graduation ceremony, Delaney said, she plans to walk to receive her diploma. She will be aided by Howard, who will be on stage among the educators present.

Despite everything thrown in her path, the teen is graduating on time, with a 3.3 grade-point average, having made the honor roll most of the time.

“The most days she missed was freshman year, when she had the transplant. I think she missed 66 days, but she was doing home-school tutoring,” O’Hagan said. “It’s incredible. There’s nothing else to say. Being with her, there was never any doubt. She fought tooth and nail to complete this. For her to be held back and not graduate with this ground of kids that she grew up with . . . she said, ‘That’s a no-go. We’re going to do this.’ . . . It’s going to be very emotional.”

Mount Vernon history teacher Amanda Bierschenk said Delaney is an inspiration to her peers.

“I think Delaney is an example of what all of us should strive to be in life, someone that tackles obstacles head-on and overcomes them with a smile on her face,” Bierschenk said. “Delaney is a student that makes teaching rewarding.”

Physics teacher Avi Shapiro said Delaney is quick to learn, focused on her studies and wants to be involved as much as possible.

“Despite her limited mobility, she tried to participate in everything that she could,” he said. “When she could not do something due to physical limitations, she accepted it with no visible sadness. In point of fact, she handled it far better than I would have under the same circumstances. . . . I believe that what everyone can take away from knowing Delaney is this: You should be a good and honest person. You should try to learn about the world around you in areas that interest you. Finally, no matter what your limits are you should strive to reach them, without excuses.”

Delaney attributes her success to the teachers who often have given up their off time to visit her home and tutor her.

“A couple of teachers from school would come at night [for a couple of hours each] and help tutor me,” she said. “My teachers helped me a lot. I was able to receive e-mails from teachers with assignments. I was constantly on my netbook in the hospital. . . . Usually, people [who have medical conditions] gradually integrate back into school when they are done with in-patient stays. I didn’t want to do that. I wanted to get right back into it. . . . I keep making honor roll. My parents love it. . . . The last four years, I’ve really tried to keep things the same as everyone else as much as possible.”

On graduating, Delaney said, “Mostly it means that I’ll finally be done with high school. But most of my friends already know what they are going to do after high school.”

Delaney’s mother and father, Joe O’Hagan, said the plan is to enroll her in the Woodrow Wilson Rehabilitation Center to help her regain some of the cognitive and motor skills she lost.

After that, the family is hoping she can enroll at Northern Virginia Community College, which would allow her to take college courses but have the support of her family and friends nearby. Delaney also is hoping to get her driver’s license this summer, with the goal of inheriting her brother’s gold Nissan Maxima.

“I feel like, if you’re committed to it, it’s not very hard to keep up with school,” Delaney said, offering this advice to students in similar situations: “Stick through it because you know your family is always there to support you. It will get easier.”