Coauthor Eric Smith, M.D., of Cincinnati Children's Hospital Medical Center conducted tests which showed the man, his patient, to be severely estrogen resistant, a condition normally considered deadly to the developing male embryo.

Knowing of Korach's development of an estrogen receptor knock-out mouse, Smith sent samples of the man's DNA to Korach's lab at NIEHS, where evaluation revealed a mutation in the gene encoding the estrogen receptor. The case was the first reported mutation of this gene resulting in a living person who is hormonally insensitive to estrogen.

The finding, published in the New England Journal of Medicine (331:1056-61, 1994) may provide clues to some childhood growth disorders. Estrogen is the principal hormone involved in the final fusion of the epiphyses, the plates at the end of the bones whose closure is necessary for bones to stop lengthening. Though it is the female sex hormone, estrogen is also important in males for normal build-up of bone-mineral mass.

Dr. Korach attributed interest in the paper to "the uniqueness and novelty of the findings," which debunked the long-held notion that this mutation is lethal. "We hope it will allow us to make people aware that this mutation can exist in the human population," Korach told The Scientist.