Figure 2.

Ascertainment Bias and Anticipation in Glu200Lys Pedigree Data

(A) Distribution of age of onset or death by ascertainment mode.

(B) Years of onset or death, when known, occur overwhelmingly in the 25-year window since the mutation’s discovery in 1989.

(C) Year of birth and age of onset are artifactually correlated. This correlation is strongest in directly ascertained individuals (black line) but remains highly significant when indirectly ascertained individuals (gray points) are included in addition (dashed black line).

(D) Parent versus child age of onset or death. Points below the diagonal line indicate pairs in which the child dies younger than the parent. Directly ascertained pairs (black points) fall categorically below the line, pairs with one directly ascertained member are largely below the line (gray points), and pairs in which both individuals are indirectly ascertained fall on both sides (white points).