MOSCOW - President Rodrigo Duterte on Saturday said he has a condition called myasthenia gravis, a chronic autoimmune neuromuscular disease.

Duterte talked about his condition during the Filipino community meeting in Moscow Saturday, as he spoke about admiring a Filipina singer whom he just had a duet with.

The President said that his condition affects the muscles in his eyes.

“Ganun ako eh. May talent ako, magtingin ako sa'yo, 'yung isang mata ko bumaba. Kita mo maliit 'yung isa, tingnan mo. O 'di maliit. O 'yun. Nag... nagsasariling biyahe 'yan. [laughter]."

(That's how I am. I have a talent, I'll look at you [then] one of my eyes will drop. You can see one of them is smaller. It's smaller. It goes its own way.)

"Actually my... that's myasthenia gravis. It's a nerve malfunction. I got it from my... exactly from my grandfather, ganun rin siya (he also has it). So, I believe really in genetics. Kung anong sa kanya, nakuha ko eh (What he has, I inherited),” Duterte said.

The US National Institute of Neurological Diseases and Stroke said "myasthenia gravis is a chronic autoimmune neuromuscular disease that causes weakness in the skeletal muscles, which are responsible for breathing and moving parts of the body, including the arms and legs.”

The Institute said that the condition causes “muscle weakness that worsens after periods of activity and improves after periods of rest."

Certain muscles such as those that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are often (but not always) involved in the disorder, the Institute said.

The muscles that control breathing and neck and limb movements may also be affected, it added.

"There is no known cure but with current therapies most cases of myasthenia gravis are not as "grave" as the name implies. Available treatments can control symptoms and often allow people to have a relatively high quality of life. Most individuals with the condition have a normal life expectancy," the Institute said.

In 2016, Duterte also admitted that he suffered from Buerger's disease, a cause of blockages in the blood vessels, associated with smoking during his youth.

In 2017, Duterte also spoke about using fentanyl to manage pain from a spinal injury.