TODAY | May 27, 2013
>>> now to the story of a mother facing both hope and heartbreak. her two sons have a deadly disease, but only one is getting a potentially life-saving treatment. here's nbc 's janet shamlian .
>> reporter: against improbable odds, jen mcnairy has two boys are the same genetic disease that slowly robs children of their muscles.
>> i can do it.
>> reporter: muscular dystrophy is usually fatal by age 20.
>> it was actually pretty shocking because i had been told that they couldn't both have it because i'm not a carrier.
>> reporter: but that's just the start of jen's heartbreak. one of her children, max, is improving every day while 14-year-old austin is slowly dying.
>> he can't get into a chair out of his wheelchair into his bed, onto the toilet. so he's become total care.
>> reporter: max is getting better, she says, because only he qualified for the clinical trial of a promising drug. she says he's running around again, climbing stairs. he even joined a soccer team . is it fair to call it life changing?
>> absolutely. it's a miracle. it really is a miracle drug . this is something that nobody ever expected, and he looks like an almost normal 11-year-old boy.
>> reporter: nationwide children's hospital is running the drug trial . doctors say other children are also improving.
>> everything i can tell indicates that this is a winner. it's a game changer for the disease.
>> reporter: austin didn't qualify because he was already in a wheelchair. but jen is determined to save him and other dmd children before it's too late. what is the prognosis for austin ? if he doesn't get this drug?
>> in the next six or seven years, he will die. but we hope that that doesn't happen.
>> reporter: it's more than hope. she's become an advocate, asking the fda for accelerated approval of the drug which could make it available to children in a year instead of the usual four. the fda tells nbc news it's reviewing the application. austin knows his time is slipping away.
>> it's really hard because i know i'm getting worse, and he's getting better.
>> reporter: would you like to take the medicine, too?
>> reporter: a mother dealing with heartbreak and hope on a quest to save both her sons. for "today," janet shamlian , nbc news, columbus, ohio.