While still in the womb back in July, Mebane's daughter, Makenna, was diagnosed with a heart defect as a result of a chromosomal condition called trisomy 13.

The family moved to Omaha, Nebraska where Mebane's wife, Amena, and unborn child could be treated by doctors who specialized in the condition.

Makenna was born more than 1 month premature in November and later developed an intestinal infection known as Necrotizing Enterocolitis (also known as NEC) -- a fast-striking, devastating condition that can be fatal if not caught and treated immediately.

Doctors treated Makenna for weeks -- and Mebane used the team owner's private jet to travel to the last 2 regular season games when Makenna's health seemed to be stabilizing.

But unfortunately, her health took a turn for the worse earlier this month and she passed away on January 3.

Obviously, Mebane is devastated -- but says he plans to play in the Chargers' playoff game against the New England Patriots this weekend.