A NEWLY discovered gene could shed light on why some people develop as girls
even though they have a boy鈥檚 Y chromosome.
David Ornitz and his colleagues at Washington University Medical School in St
Louis, Missouri, engineered mice to lack a gene called Fgf9, which
makes fibroblast growth factor 9. They expected this to shrivel the mice鈥檚
lungs, and it did鈥攁ll 24 mice died at birth. But they were also surprised
to find that 10 male mice in the study had unexpectedly lost their manhood and
developed female genitalia. 鈥淭he male sex organs had completely regressed,鈥� says
Ornitz.
The experiments suggest that the growth factor orders the multiplication and
specialisation of cells which grow into testes, and tells those cells where to
go. Without this gene, males develop female sex organs by default (Cell,
vol 104, p 875).
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