['To investigate the expression level of genes located in chromosome 21 in the brain tissues of Down syndrome(DS).', 'An optimized semi-quantitative RT-PCR method was used to evaluate the expression levels of seven genes encoded in chromosome 21 in fetal cortex brain and cerebellum of DS and the control at the end of 20 weeks of gestation. B2M was used as internal reference to normalize cell loss.', 'The expression levels of 6 genes in cortex and cerebellum, including DYRK1A, SYNJ1, PCP4, C21orf5, C21orf2 and C21orf106, were comparable between DS and the control. ANA, a cell-cycle negative regulatory gene, was over-expressed dramatically in the cortex but not in the cerebellum of DS.'] Is [ Cell-cycle negative regulatory gene ANA over-expressed in the brain tissues of patients with Down syndrome ]?