In Genetic Disorders, One Size Does Not Fit All.

In drug development, preclinical studies often do not predict human benefit. Why not, then, go right to the source-patients with rare diseases and, more importantly, with specific various genetic mutations that, in aggregate, define the phenotypic clinical disorder? In this issue, Genova et al. describe how induced pluripotent stem cells from patients with two genetic disorders (ataxia-telangiectasia and Aicardi-Goutières syndrome) can be used to better predict responses to immunosuppressive therapy.