“…These include affected sib-pair (ASP) linkage studies 16 -24 and studies of extended multigenerational families. 25,26 These studies suggested linkage to 1p36, 2q21, 2q35, 4q13.2, 5p13, 5q13.1, 5q33.3, 6q12, 6q22 -23, 7p13, 7q21, 9q22, 11q22, 13q12, 14q12, 15q15, 16q23, 17p11, and several other regions with nominally significant evidence of linkage but no outstanding replications. The continued failure to replicate linkage findings for ADHD has led researchers to believe that genes affecting ADHD have common variants with very small effects that cannot be detected successfully with methods relying on linkage and hence advocated the use of association analysis.…”