Eric Dane, who shared his amyotrophic lateral sclerosis (ALS) diagnosis in April, has disclosed the initial symptom he noticed about 18 months ago.

“I began to feel some weakness in my right hand, but I didn’t pay much attention to it then,” the 52-year-old actor told Diane Sawyer on “Good Morning America” on Monday.

“I thought maybe I had been texting too much or my hand was fatigued. But a few weeks later, I noticed it had gotten a little worse.”

Dane mentioned that he consulted multiple hand specialists and then visited two neurologists. After nine months of medical consultations, he eventually got his “sobering” diagnosis.

Since then, Dane’s right arm — his dominant — has “completely stopped working.”

“And then your left arm is fine?” Sawyer, 79, asked.

“No, it’s going,” the “Grey’s Anatomy” alum replied, adding that he feels he has “a few more months” left of use of his left.

He’s also “worried” about his legs going next.

A few months ago, the father of two — a former competitive swimmer and water polo star — was on a boat trip with one of his teenage daughters, whom he shares with his on-again wife, Rebecca Gayheart.

When he jumped into the ocean, he quickly realized he “couldn’t swim or generate enough power to get [himself] back to the boat.” It was then that he had to accept, “I’m not safe in the water anymore.”

As his daughter “drag[ged]” him back to the boat, Dane was “breaking down in tears.”

“I was just heartbroken” he lamented.

Asked how “angry” the illness makes him, the “Euphoria” star responded sternly, “Very.”

He elaborated, “I’m angry because my father was taken from me when I was young, and now there’s a very good chance I’m going to be taken from my girls while they’re very young.”

(Dane’s dad died by suicide when the actor was 7.)

As he continues “fighting” the disease, which is largely “out of [his] control,” Dane plans to “spend time with [his] family and work a little bit — if [he] can.”

He made sure to note that he doesn’t believe this is “the end” of his story.

ALS, according to the ALS Association, is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord, leading to the eventual demise of motor neurons.

When the motor neurons die, the brain stops being able to initiate and control muscle movement, which can lead to the inability to speak, eat, move and breathe. There is no known cure.