Trisomy is a mutation that results in a cell having an extra

Down syndrome is an example of a condition caused by trisomy. People with Down syndrome typically have three copies of chromosome 21 in each cell, for a total of 47 chromosomes per cell. Monosomy, or the loss of one chromosome in cells, is another kind of aneuploidy

Aneutral atom must have the same number of neutrons and protons? no, they must have the same number of protons and electrons