Linkage of bipolar affective disorders to markers on chromosome 11p is excluded in a second lateral extension of Amish pedigree 110.

Linkage between markers on chromosome 11p and bipolar affective disorders can be excluded in a second large lateral extension of the original Amish Pedigree 110. These results, together with previous negative linkage findings, suggest that there is not one single gene on 11p conferring susceptibility for bipolar affective disorders among the Old Order Amish.