Fragile sites and chromosome breakpoints in constitutional rearrangements II. Spontaneous abortions, stillbirths and newborns.

Certain fragile sites may possibly predispose to chromosome breakage and rearrangements in meiosis. To test this hypothesis, we examined 894 breakpoints found in spontaneous abortions, stillbirths and livebirths of which 165 (18.5%) were in bands with fragile sites. Compared to an expectation of 98 (11%), there was a significant excess of breakpoints in fragile site bands (P less than 0.001). Together with data from amniocenteses, there is now evidence suggesting that certain fragile sites may be prone to fragility in meiosis.