Backstreet Boy Brian Littrell's Son Ill

Backstreet Boy Brian Littrell and his wife, Leighanne, have been served devastating news before the holiday. Their 6-year-old son, Baylee, has been diagnosed with atypical Kawasaki Disease, E! reports.

The family spent last week in Atlanta at the Scottish Rite children's hospital. Baylee was released Saturday after entering the hospital with symptoms like erythema multiforme, hand, foot, and mouth disease, and strep throat.

Littrell wrote on his Web site, "After receiving a biopsy, blood tests, an EKG and two echocardiograms, Baylee was finally diagnosed with A-Typical [sic] Kawasaki Disease. We would like to stress A-Typical because Baylee did not have textbook symptoms of any of the viruses they thought he had."

Littrell also wanted to "thank everyone who prayed for us as well as all of the emails and phone calls," and he and Leighanne are "humbled" by the overwhelming amount of support they have received.

"Kawasaki Disease causes inflammation in the coronary arteries as well as the walls of the small and medium sized arteries throughout the body," Littrell added.

A pediatric cardiologist will monitor Baylee during the next six to eight weeks in order to see that his IVIG treatment will be effective. The IVIG is to help lower the inflammation in his coronary arteries.