In the third genome -wide linkage study,137121 individuals in 26 multigenerational families were genotyped with markers with an average spacing of 10 centimorgans (cM). (Note: a centimorgan is defined as the distance on a chromosome in which 1% crossing over occurs. Given the success of the human genome project, this metric is rarely used any more, since it is now possible to determine precisely the number of base pairs between markers.) As in the first study published by these investigators,135 all relatives were assessed with a semistructured psychiatric interview, and best estimate lifetime psychiatric diagnoses were made using data from these interviews and all other available sources of information. The maximum nonparametric LOD (NLOD) score observed was 2.43 for markers on chromosome 10p15. When data from Hanna et al's first genome scan were analyzed together with the current marker data, the maximum NLOD score in the 10p15 region was decreased to 1.79. These investigators followed up the linkage findings with a family-based association analysis which examined 35 single-nucleotide polymorphisms (SNPs) in this 10p15 region. Association was detected on 10p15 with
