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THE MOST severe form of hemophilia A, in which there is virtually no factor VIII activity in the blood, has become an enigma to molecular biologists seeking a genetic basis for the disorder.
Over the years, chromosome linkage analysis has linked hemophilia A to the factor VIII gene on the X chromosome in every family studied by this technique. Yet in a study published last month, researchers found no mutations in the factor VIII gene in half of the severe cases examined (Proc Natl Acad Sci USA. 1991;88:7405-7409).
"We have found no point mutations, no deletions, no insertions, and no substitutions," says Stylianos Antonarakis, MD, associate professor of pediatrics at The Johns Hopkins University School of Medicine, Baltimore, Md. "The entire coding region of the gene is normal."
A First in Genetics
"This is the first time in which we have had a well-mapped, well-known gene in a relatively common
Randall T. Gene Scene: Factor VIII Gene Explains Just Half of Severe Cases of Hemophilia A. JAMA. 1991;266(12):1612-1613. doi:10.1001/jama.1991.03470120014005