Arizona Cardinals wide receiver John Brown has not practiced this week due to what was listed as a hamstring injury.
On Friday, Cardinals coach Bruce Arians revealed that Brown's health issues were not actually the result of an injured hamstring, but rather due to sickle cell trait that had been causing Brown leg pain since pregame warmups before the Cards' Monday Night Football matchup against the New York Jets.
Arians said Brown is happy to have received a diagnosis and the team is "investigating how to help him." However, Brown is listed as doubtful for Sunday night's game vs. the visiting Seattle Seahawks.
Sickle cell trait impacts the function and shape of red blood cells. According to WebMD.com, "in rare cases, a person with sickle cell trait may have muscle pain or other serious health problems. These problems can happen under certain extreme conditions, such as intense exercise, overheating, or being at a high altitude."
The 26-year-old Brown was selected by the Cardinals in the third round of the 2014 NFL Draft. He has 24 catches for 301 yards this season.
Brown missed most of training camp while suffering from concussion symptoms.