The wide receiver, 22, announced the diagnosis on Sunday but said he’s in “good spirits” and that he expects to make a recovery.
“I am currently receiving great medical care, am in good spirits and I expect to make a recovery at a later point in time.
“As a result of this diagnosis, I will likely not be playing football this season. My main focus will be on my health and recovery.
“Thank you in advance for your support and well-wishes. I cannot wait to come back stronger than ever. God Bless.”
‘John has overcome every challenge’
Metchie was the 44th overall pick in this year’s NFL draft.
The Alabama product had 96 catches for 1,142 yards and eight touchdowns last season before a period on the sidelines after tearing his ACL in December.
His former coach at Alabama, Nick Saban, sent his best wishes.
“It’s a blessing that he is in a city known for great care and with an organization, in the Houston Texans, who will be with him throughout this journey.
“Our thoughts and prayers will remain with him throughout this battle.”