Youngs was selected in a 41-man squad by Warren Gatland last month, along with fellow number nines Conor Murray and Rhys Webb.
However, the 27-year-old informed Gatland this weekend that he would be staying at home, due to the terminal diagnosis given to the wife of his brother and fellow England international Tom Youngs.
A statement on Leicester’s official website read: “Leicester Tigers scrum-half Ben Youngs has withdrawn from the squad for the British & Irish Lions tour to New Zealand for family reasons.
“The wife of Ben’s brother Tom has been battling cancer for three years and the family has now received the devastating news that the illness is terminal.”
— England Rugby (@EnglandRugby) May 6, 2017
Ben Youngs added: “We are a very close family and, as I am sure everyone can respect, time is now precious together.
“The most important thing for me at this difficult time is to be able to offer as much support as I can to Tom and his family in the remaining time we all have together.
“It is a great honour to be selected as a member of the British & Irish Lions squad and I would like to thank Warren Gatland, the staff and the other players for their understanding in this situation. I wish them well and, like all rugby supporters in British and Ireland, hope they have a successful tour.”
Both Youngs brothers are set to represent the Tigers for the remainder of the Premiership season. Tom scored a try on Saturday as Leicester secured a semi-final berth by beating Worcester Warriors 28-23.
Watch every game of the Lions Tour of NZ streaming live on rugbypass.com, home of the best online rugby coverage including news, highlights, previews & reviews, live scores, and more!
Sign up to our mailing list here and we’ll keep you up to the minute with weekly updates from the world of rugby.