"Effective immediately, I have chosen to take an extended leave of absence to focus my attention and intention on my wife's complete recovery from her recent diagnosis of breast cancer", Smith said in a statement.
Smith called the decision "extremely difficult" and acknowledged he still wants to bring Houston a championship.
His leave of absence comes after a hard 4-12 season for the Texans that brought rumors of a "toxic" relationship between Smith and coach Bill O'Brien.
Oil near 2015 highs on strong China data
Front-month prices are about 12 per cent higher this year, after rising 45 per cent - the most since 2009 - in 2016. The US expects production to top 10 million barrels a day in the coming year.
A source told Sporting News that O'Brien is planning to pitch a he-goes-or-I-go scenario to McNair because of the ongoing friction in his working relationship with Smith. That tracks with what Wilson reported, that it could be an "either-or-situation" with O'Brien and Smith.
This means Bill O'Brien will return for his fifth year as coach.
There has been speculation about O'Brien's future in Houston after the Texans struggled to a 4-12 season.
Pulwama Encounter: Four CRPF men, two militants killed
The militants initially said to be two, barged into the Lethpora centre from the hillside and killed two CRPF men. The CRPF camp also serves as training centre for troops inducted for counter-militancy operations in Kashmir.
From a contractual standpoint, O'Brien has limited leverage since one year remains on his Texans deal.
Last week, O'Brien said he would be willing to coach the final season without signing a contract extension and said earlier this month that he "will never quit as head football coach of the Houston Texans". They have been to the playoffs four times and won three postseason games.
Oyintiloye Urges Youths to Learn Persistence — George Weah's Victory
The 51-year-old Weah, a senator who entered politics more than a decade ago, will take over in January. Weah adds that "we have a lot to do together to accelerate the building of tomorrow's Africa".