Like most 7-year-old boys, Zach Guillot spends his days playing Legos. He just does it from a hospital bed.

In February 2010, Zach began not feeling well.

His mother, Julie Guillot, said, "I did begin to google his symptoms, and every time it came up with signs of childhood cancer."

A blood test showed Zach had AML leukemia - a more resistent and difficult-to-treat trype of luekemia.

Father Jeff Guillot said, "It`s devastating. The last thing you`d want to hear as a parent, that your child has a disease like leukemia."

Zach's mom said the family went into survival mode.

After several courses of intense chemotherapy and a bone marrow transplant from Zach's younger brother, Jake, the cancer went into remission for over a year.

"We hoped and prayed and felt good that everything had worked well," Mr. Guillot said, "and he was back to himself and back to the routine of what every six or seven year old should be in. Then, he started not wanting to go to school."

In November 2011, Zach returned to Children's Medical Center in Dallas for blood work.

Mrs. Guillot said, "They saw his counts had dropped slightly. So, they took him back for an aspiration. We had to wait a whole night. That was the worst night of my life."

The week before Thanksgiving, Zach learned his cancer had relapsed.

Zach's mother said, "It was like someone just took a massive baseball bat and swung it into your stomach."

Mr. Guillot said, "This time is harder, because we know it`s an uphill battle."

Doctors said Zach's brother was too close of a genetic match. Zach would need an unrelated bone marrow donor, and soon.

"Finding a donor for Zach is the potential cure for him, as far as I know," Mr.s Guillot said.

A bone marrow drive will be held Sunday to find a potential match for Zach and other children in need of a transplant.

Mrs. Guillot said, "Donating your marrow is as significant as donating your heart, your lung, your kidney, and you can walk away from it, and you`ve just saved somebody."

The blood marrow drive will be held at Parish Episcopal School on Hillcrest Drive in Dallas on Sunday from 12 p.m. to 6 p.m.

The Guillot family encourages those who wish to be tested as a potential match and donor to attend the drive or visit http://www.facebook.com/pages/ZachAttacksLeukemia/269535426431785?ref=tn_tnmn or www.getswab¿bed.org.