sentence: Humans are diploid organisms.
sentences_before: It comes from a problem with the genes.
sentences_after: This means that for each chromosome, there are two copies, one from the mother, and one from the father. During meiosis the number is reduced to one set of chromosomes. People with Down syndrome have an extra copy of chromosome 21, or part of it. They usually have some measure of mental handicap, but this can range from mild to severe.
concept_name: human
headings: Down syndrome
categories: Trisomies