Scientists reported Thursday they had found the approximate location of a gene that causes a crippling disease in as many as 20,000 Americans.

The work is a step toward earlier diagnosis of the illness, Friedreich's ataxia, and toward detection of healthy people who unknowingly carry the gene and can pass it to their offspring, the researchers said.Scientists hope to isolate the gene as a clue to possible treatments. The disease now has no cure or specific treatment.

The study was reported in Thursday's issue of the British journal Nature by researchers at St. Mary's Hospital Medical School in London, the Howard Hughes Medical Institute at the University of Utah School of Medicine, and the Karolinska Institute in Stockholm, Sweden.

Friedreich's ataxia afflicts probably 15,000 to 20,000 people in the United States.