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Definition

Containing one copy of each chromosome. Human gametes (egg and sperm cells) are haploid, containing 22 autosomes and one sex chromosome.

Use in clinical context

During fertilisation an egg and sperm combine to form a cell that contains a complete complement of DNA. In humans this is a total of 46 chromosomes in pairs, termed diploid. If a cell contains any more or less than this number (aneuploidy) it can cause problems. Each parent contributes one of each chromosome, which is half their genome, to their gametes (egg or sperm) and therefore these cells are haploid. The half that each egg or sperm gets is random so that all offspring, with the exception of monozygotic twins, are different from each other.

Last updated on 29th May, 2019