What does euploidy mean?
Euploidy is a term from cytogenetics describing the condition of a cell or organism whose chromosome number is an exact multiple of the haploid number for its species — in other words, it possesses whole, complete sets of chromosomes. Humans, for example, are normally diploid, carrying two sets of 23 chromosomes, which represents a euploid state. The concept matters chiefly because it stands in contrast to aneuploidy, in which individual chromosomes are missing, extra, or otherwise unbalanced; such imbalances typically cause developmental problems, miscarriage, or conditions such as Down syndrome. In reproductive medicine, confirming euploidy in embryos through preimplantation genetic testing has become central to modern IVF practice, since euploid embryos are far more likely to implant successfully. Euploidy also encompasses polyploidy, where entire extra sets of chromosomes are present — a common and often benign phenomenon in plants. Though strictly a specialist term, euploidy has gained wider currency as genetic screening has entered everyday medical conversation.
nounThe condition of a cell or organism having a complete set(s) of chromosomes, i.e. a chromosome number that is an exact multiple of the haploid number for the species. It contrasts with aneuploidy, in which chromosomes are missing or present in excess.
- The state of possessing a chromosome number that is an exact multiple of the haploid number, characteristic of healthy cells in many organisms.
"Preimplantation genetic testing revealed euploidy in three of the five embryos."
"Embryos demonstrating euploidy have a significantly higher likelihood of successful implantation."
"In plants, euploidy can occur naturally through whole-genome duplication, giving rise to fertile polyploid lineages."
Rarely pluralized; the uncountable singular form is standard even when discussing multiple cases.
"The study compared euploidies across several cell lines."
In IVF labs, 'euploidy' is the single most hopeful word a patient can hear — it means an embryo has exactly the right number of chromosomes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of euploidy
The word euploidy combines the Greek prefix 'eu-', meaning 'good' or 'well' (the same element found in words like euphoria and euthanasia), with '-ploidy', a suffix coined in early twentieth-century cytogenetics from Greek '-ploos', meaning 'fold', on the model of 'haploid' and 'diploid'. It was formed to describe cells whose chromosomal endowment was properly proportioned in whole sets. Its direct antonym, aneuploidy, was created alongside it using the negative prefix 'an-'.
Related word forms
How euploidy is actually used
A technical term used almost exclusively in genetics, cytogenetics, reproductive medicine, and botany. It is neutral in connotation within those fields, though in fertility contexts it often carries implicitly positive associations.
Easily confused with euploidy
Aneuploidy refers to an abnormal chromosome count that deviates from an exact multiple of the haploid number, whereas euploidy denotes a normal, complete chromosomal complement.
Polyploidy is one specific kind of euploidy in which an organism carries more than two complete sets of chromosomes, rather than the general state of having whole sets.