Sister chromatid exchanges in the peripheral lymphocytes of newborns with Down syndrome after in vitro exposure to blue or green light.

This study determines whether irradiation by blue or green light has an adverse effect on the DNA of Down syndrome (DS) cells by examining the sister chromatid exchange (SCE) frequency of peripheral lymphocytes obtained from five neonates with DS and five karyotypically normal neonates (control). Lymphocytes in G0 of the cell cycle were irradiated with blue or green fluorescent light for 1, 2, 4 or 6 h, and then cultured using a conventional method. Our results revealed that the induction of SCEs per cell in both groups increased in a dose-dependent manner, although more SCEs were respectively induced by the blue light. In addition, after 6 h of blue light irradiation, the net-induced SCEs in the DS groups were higher than those in the control groups.