After publication, we identified a systematic genotyping error that affects the boundaries of two congenic lines reported in Table 1. Lines 1 and 4 should have been defined by a distal homozygous B6 genotype at 98.87 Mb (rs27102250) rather than 96.49 Mb (rs27056693). Line 4 should have been defined by a proximal homozygous B6 genotype at 86.82 Mb (rs13481139) rather than 87.81 Mb (rs29397485).

The newly defined boundaries do not alter the main conclusion of the paper, which was that the QTL for methamphetamine sensitivity is most likely driven by an epistatic interaction of two or more alleles within the congenic segment. However, the 2.38 Mb distal extension of Line 1 means that four additional genes that possess cis-acting expression QTLs should have been included in Table 2 (q < 0.05 for analysis of the congenic region): 1700001P01Rik (97.63 Mb; A/J > B6), Osbpl7 (96.91 Mb; A/J < B6), Copz2 (96.71 Mb; A/J < B6), and Pcgf2 (97.55 Mb; A/J > B6). We apologize for this minor error.