U.S. Sen. Johnny Isakson announced Wednesday he will resign at the end of 2019.

“It goes against every fiber of my being to leave in the middle of my Senate term, but I know it’s the right thing to do on behalf of my state,” the 74-year-old Isakson said in a statement, citing his declining health.

» Georgia's Isakson to resign from Senate at end of 2019

Here are five things to know about the 74-year-old who has served Georgia for more than four decades.

1. He was born here

John Hardy Isakson was born December 28, 1944, in Atlanta, to Edwin Andrew and Julia Isakson.

2. Before politics

Isakson graduated from the University of Georgia in 1966 and served in the Georgia Air National Guard from 1966 until 1972. In 1967, he opened the first Cobb County office of Northside Realty, an Atlanta-area real estate firm his father helped to establish. He was company president for 22 years.

» PHOTOS: Johnny Isakson through the years.

3. Family

He and his wife, Dianne, married in 1968 and have three children — John, Julie and Kevin — and eight grandchildren. They live in Marietta and attend Mount Zion United Methodist Church, where Isakson previously taught sixth-grade Sunday school for 30

years.

4. Politics

According to his bio, Isakson "holds the distinction of being the only Georgian ever to have been elected to the state House, state Senate, U.S. House and U.S. Senate. In addition, in 2016 he became the first Georgia Republican ever to be elected to a third term in the U.S. Senate."

» Isakson timeline

5. Health

In 2015, Isakson was diagnosed with Parkinson's disease. He has suffered several falls since the diagnosis, including this past July, when he broke four ribs. During his retirement announcement Wednesday, he revealed he'd undergone surgery to remove a growth on his kidney.

» How will U.S. Sen. Johnny Isakson's replacement be chosen?