Слово встречается в следующем контексте:

When loss of the chromosome occurs later than the blastoderm stage, the incipient male cells die because they have problems with dosage compensation (the mechanism whereby gene expression on the one X chromosome of males is increased relative to the two chromosomes of females so that both sexes have the same amount of gene products).
When loss of the X chromosome occurs very late in development, _perdurance_ of some gene products is sufficient and again small male patches survive.

Заранее спасибо,

Natalya.

я конечно не медик но вроде что-то похожее на правду:)