Southern California freshman Frankie Telfort has a heart problem that will prevent him from playing for the Trojans.

Telfort, a 17-year-old Miami native considered one of the top linebacker prospects in the country, has been diagnosed with hypertrophic cardiomyopathy, a serious genetic heart condition that has figured prominently in the lives and deaths of many notable athletes in recent years.

USC couldn't clear Telfort to play after examinations by several top heart specialists in Los Angeles and another opinion from the Minneapolis Heart Institute. The condition causes the heart muscle to thicken, making it difficult to pump blood.

"This is obviously very difficult news for Frankie, his family and all of us in the football program," coach Pete Carroll said. "But we're very thankful doctors discovered the issue before it led to anything worse."

USC will honor Telfort's full scholarship, athletic director Mike Garrett said.

Telfort, who attended Miami's Gulliver Prep, was ranked the No. 8 linebacker in last spring's recruiting class by Rivals.com. Though somewhat undersized at 5-foot-11, Telfort was thought to have a promising career ahead at linebacker or safety for the Trojans.

"Everybody's football career unfortunately ends at some point, and no one's ever ready for it," Carroll said. "For some guys, it comes sooner than expected. But you're a football player and a Trojan for life, and Frankie is definitely both."

Hypertrophic cardiomyopathy affects roughly one in every 500 people, according to the Mayo Clinic, and is the top cause of sudden heart-related death in people under 30 years old. Although it causes no significant health problems for many, the condition can produce dangerous problems with the heart's rhythm.

Veteran NBA guard Cuttino Mobley retired last season after being diagnosed with the condition, which also was linked to the deaths of Boston Celtics forward Reggie Lewis, Loyola Marymount star Hank Gathers and retired Portland Trail Blazers center Kevin Duckworth.

Marathoner Ryan Shay, San Francisco 49ers lineman Thomas Herrion, Atlanta Hawks center Jason Collier and former NHL player Sergei Zholtok are among many other athletes also believed to have died from conditions related to enlarged hearts.