SOX2 and Huntington disease: We have demonstrated that HD patient-specific pluripotent stem cells can be cultured over multiple passages without losing CAG repeat length or pluripotent markers such as SSEA-4, NANOG, OCT4 and SOX2.  These markers are absent in the fibroblasts in which the iPSCs were derived (data not shown).  As might be expected, we do detect altered signalling when comparing the normal iPSCs to the HD iPSCs.  In this case, we detect altered ERK phosphorylation in resting cells and in response to bFGF.