Liberal MP Mauril Bélanger says he has been diagnosed with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, and while he plans to continue to represent the riding of Ottawa-Vanier, will drop out of the race to become Speaker of the House of Commons. 

The disease, which takes its name from the famed baseball player who was stricken with the disease in the prime of his career, causes a person to lose control of their muscles. 

Motor neurons that transmit electrical impulses from the brain to the muscles in the body start to fail, causing the muscles to lose strength, atrophy and die.

The average life expectancy after diagnosis is three to five years.

Bélanger, 60, has recently suffered voice problems, a concern when he was seeking the job of Speaker of the House of Commons.

He was re-elected on Oct. 19 with nearly 58% of the vote in Ottawa–Vanier, a riding he has held since a by-election in 1995.

"I wish to thank everyone who has encouraged me and supported my candidacy for Speaker. I will be eternally grateful. Thank you to my election team and the voters of Ottawa–Vanier for the privilege of serving them," Bélanger wrote in a letter to Liberal caucus members.

Bélanger, who served as the associate defence minister under Liberal prime minister Jean Chrétien, had been having problems speaking in recent months, avoiding media interviews and speaking on the phone.

Last week, he announced that he had undergone a series of MRIs and a CT scan that had come back normal, but a visit to an Ottawa neurologist on Friday revealed he has the incurable disease.

Prime Minister Justin Trudeau tweeted his best wishes Monday, telling Bélanger that his colleagues "will always have your back."

Bélanger and his wife, Catherine, have three grandchildren.

Below is the note Bélanger sent this morning to his colleagues:

Dear Colleague,

Last Friday, I met with highly respected Ottawa neurologist Dr. Pierre Bourque. After undergoing a series of tests, he has diagnosed me with Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease. It is an incurable disease.

Under the doctor's advice, I have decided to withdraw my candidacy for Speaker of the House of Commons today but shall continue as the proud Member of Parliament for Ottawa-Vanier.

I wish to thank everyone who has encouraged me and supported my candidacy for Speaker. I will be eternally grateful. Thank you to my election team and the voters of Ottawa-Vanier for the privilege of serving them.

I look forward to seeing you all at the opening of Parliament.