Costa Rican sample, but five instances of var321 were found in Ashkenazi GTS patients, two of whom transmitted var321 to affected children. This high number of SLITRK1 var321 polymorphisms in the Ashkenazi sample prompted analysis of this variant in 256 Ashkenazi control individuals. One unaffected Ashkenazi individual was identified with SLITRK1 var321, suggesting overrepresentation of the var321 polymorphism in Ashkenazi Jews and raising the possibility that population stratification of Ashkenazis in GTS cases compared to controls might account for the association between GTS and SLITRK1 var321 in the original study [86]. Finally, a recent study by Miranda et al. [94] screened 208 GTS affected children from 154 nuclear families for association between common single nucleotide polymorphisms (SNPs) in SLITRK1 and GTS. This study detected a significant association of a common single polymorphism and of a haplotype of three tagging SNPs located in SLITRK1, albeit at an experiment-wide threshold of p<0.05 following permutation. Future studies of larger samples will be needed to attempt to replicate this finding.
