“…Nerve cells, germ cells, embryonal stem cells (ES), cancer cells, or other cell types with trisomy 21 genotype are not commercially available or retrievable from the biobanks, and often they derive from induced-pluripotent stem cells (iPSC) which could suffer deep genotype rearrangements (Sobol et al, 2015) or spontaneous chromosome loss (Li et al, 2012), avoiding the identification of the alterations caused only by the trisomic genotype we are interested in. In addition, cultured children and adult skin fibroblasts have been extensively used over decades to model cellular and molecular features of trisomy 21, for example, among others: cell proliferation (Kimura et al, 2005;Segal & McCoy, 1974), enzyme activity (Chadefaux et al, 1985;Cox, 1965;Feaster, Kwok, & Epstein, 1977;Sinet, Lejeune, & Jerome, 1979;Zatorska & Jozwiak, 2002), gene expression (Sullivan et al, 2016;Urakami et al, 1996), sensitivity to radiation and DNA repair (Kedziora, Sibinska, Rozga, & Bartosz, 1986;Necchi et al, 2015;Steiner & Woods, 1982;Yotti, Glover, Trosko, & Segal, 1980). FA was tested to confirm the null effect on trisomy 21 cell lines, previously observed by other authors, when it was administered in vitro (Blehaut et al, 2010).…”