[1] Johns Hopkins Univ, Sch Med, Ctr Med Genet, Baltimore, MD 21205 USA
[2] Johns Hopkins Univ, Sch Med, Dept Gynecol, Baltimore, MD 21205 USA
[3] Johns Hopkins Univ, Sch Med, Dept Obstet, Baltimore, MD 21205 USA
[4] Johns Hopkins Univ, Program Human Genet, Baltimore, MD 21205 USA
[5] NIAID, Mol Microbiol Lab, NIH, Bethesda, MD 20892 USA