United Kingdom, Jan. 8 -- Patrick Swayze's younger brother Sean Swayze has died at the age of 63.

He passed away on December 15 at the Antelope Valley Medical Centre in Lancaster, California.

According to Sean's death certificate - obtained by TMZ - he died of acute upper gastrointestinal bleed and severe metabolic acidosis, which was caused by cirrhosis of the liver.

Cirrhosis of the liver is a condition that causes healthy liver tissue to turn into severe scar tissue as a result of alcoholism.

Sean's death certificate also revealed that he worked as a Teamster in the entertainment industry for 30 years.

He is survived by his brother Don Swayze and his children, Cassie, Kyle and Jesse.

Sean's cousin Rachel Leon paid tribute to him ...