 The human iPS is generated by direct reprogramming of human somatic cells. These hiPS cells can give rise to most tissue types in the human embryo and possess many of the properties of human embryonic stem cells hESC. The big advantage of human iPS cell over hESC is that it circumvents most of the limitations of hESC and remains the pluripotency for regeneration of cells and tissues. The unique capacity of self-renewal of iPS can provide unlimited supply of pluripotent stem cells for study. The patient-specific iPS cell lines should fundamentally eliminate the concern of immune rejection and ethical issues. The disease-specific iPS will facilitate the study of the mechanism of nucleotide expansion. It is the ideal medium to study the dynamic changes of the expansion from stem cell stage to different differentiation stages. It also creates a platform for drug development. The establishment of iPS stem cells will also make it realistic for target gene replacementcorrection therapy. 