Horned Frogs coach Gary Patterson told local reporters on Thursday during a conference call that Duggan has had the condition his entire life but it was only recently discovered in the midst of increased coronavirus testing protocols.
"Because of all the things we had in place, Max has a condition that he's had his whole life and we caught it," Patterson said, according to the Fort Worth Star-Telegram. "Right now he's in a good place and hopefully he'll be getting back some time during the season."
Patterson did not say whether Duggan would return this season.
"Right now we'll be going forward with the rest of the quarterbacks," Patterson said, according to the Star-Telegram.
Duggan appeared in all of TCU's 12 games in his true freshman season in 2019 and started the last 10, throwing for 2,077 yards, 15 touchdowns and 10 interceptions while completing 53.4% of his pass attempts.
The team's other options at quarterback include Matthew Downing, a redshirt sophomore who transferred from Georgia prior to the 2019 season but did not play last year, and Stephon Brown, a junior college transfer from Independence Community College who was ranked as the No. 1 dual-threat quarterback recruit from the 2020 junior college ranks.