Results of blind testing a method to detect carriers of the Duchenne muscular dystrophy gene.

We blind-tested a method that in earlier studies had shown increased leucine uptake in muscle fibers of biopsy specimens from three obligate carriers and seven of 11 putative carriers of the gene for Duchenne muscular dystrophy. Here, muscle samples obtained at biopsy in seven obligate carriers and nine control subjects from Brazil were examined in Canada without knowledge of the carrier status or serum enzyme concentrations. Leucine uptake was increased in four controls and within normal range in four carriers, a rate of false-positives and -negatives that underscores the need for blind-testing methods for detecting carriers of this disease.