[1] Duke Univ, Med Ctr, Dept Pediat, Durham, NC 27710 USA
[2] Mayo Clin & Mayo Fdn, Coll Med, Dept Biochem Mol Biol, Scottsdale, AZ USA
[3] Mayo Clin & Mayo Fdn, Coll Med, Tumor Biol Program, Scottsdale, AZ USA
[4] George Washington Univ, Childrens Natl Med Ctr, Res Ctr Genet Med, Washington, DC USA
[5] George Washington Univ, Dept Pediat, Washington, DC 20052 USA
[6] George Washington Univ, Dept Biochem Mol Biol, Washington, DC 20052 USA