Adolescent idiopathic scoliosis (AIS) is a common disorder with strong evidence 
for genetic predisposition. Quantitative trait loci (QTLs) for AIS 
susceptibility have been identified on chromosomes. We performed a genome-wide 
genetic linkage scan in seven multiplex families using 400 marker loci with a 
mean spacing of 8.6 cM. We used Genehunter Plus to generate linkage statistics, 
expressed as homogeneity (HLOD) scores, under dominant and recessive genetic 
models. We found a significant linkage signal on chromosome 12p, whose support 
interval extends from near 12 pter, spanning approximately 10 million bases or 
31 cM. Fine mapping within the region using 20 additional markers reveals 
maximum HLOD = 3.7 at 5 cM under a dominant inheritance model, and a split peak 
maximum HLOD = 3.2 at 8 and 18 cM under a recessive inheritance model. The 
linkage support interval contains 95 known genes. We found evidence suggestive 
of linkage on chromosomes 1, 6, 7, 8, and 14. This study is the first to find 
evidence of an AIS susceptibility locus on chromosome 12. Detection of AIS 
susceptibility QTLs on multiple chromosomes in this and other studies 
demonstrate that the condition is genetically heterogeneous.