The effect of lingering illness in the family is rarely lost on the children involved; while they seem to be getting along, they understand that things aren’t right, and in their own ways they try to do something about it.

So it is with a 7-year-old girl from South Boston, described by her mother in a letter to Globe Santa as “a smart, active, kind, and friendly little girl who is innocent and open-minded, and very well behaved.’’ The illness the family is dealing with is her mother’s odds-defying five-year bout with acute myeloid leukemia.

Mother and daughter largely rely on each other for comfort and support, teaming up every day to handle the routines of school, meals, keeping up the house, and moving around Boston, the mother said. “She amazes me every day with something new she has learned or something special she says to make me feel better when I’m ill,’’ adding that she never complains.

The mother has been unable to work because of the side effects of her medication and the relentless commitment of time that her treatment demands. The family receives a modest disability check and food stamps every month, but that doesn’t leave anything for extras, the mother says, adding that unexpected expenses mean either more debt or going without.

“My daughter deserves the world, but all I can give her is my love and despite my problems, a happy childhood,’’ the mother wrote. “She deserves gifts like other children her age. If not for you, I wouldn’t be able to get her anything.’’

Like so many of the parents, grandparents, guardians, and siblings who write to Globe Santa, a program of The Boston Globe Foundation, she offered words of gratitude. “I want to thank everyone from the founders, employees, and wonderful volunteers who work very hard together to make small miracles happen for children who otherwise have a very sad Christmas,’’ she said in her letter. “As long as I might have left . . . I will do everything in my power to keep the faith, to keep the joy and the magic of Christmas alive.’’

This mother can trust that Globe Santa will keep the joy and magic alive on Christmas Day for her daughter and for thousands of other deserving children across eastern Massachusetts.

Please visit globesanta.org to learn more about the history of Globe Santa and upcoming events, or to make a donation.

Christopher Tangney can be reached at ctangney22@hotmail.com.