euploide

Euploide, or euploid, is a term in genetics describing a chromosome complement that is an exact multiple of the haploid chromosome number (n). The concept includes haploid (1n), diploid (2n), triploid (3n), tetraploid (4n), and higher polyploids. In contrast, aneuploidy refers to chromosome numbers that are not exact multiples of n.

In many animals, the typical euploid condition is a normal diploid set. For example, humans have 2n = 46 in somatic cells and n = 23 in gametes. Aneuploid conditions, such as trisomies or monosomies, involve the gain or loss of individual chromosomes and are not euploid.

Euploidy can arise by whole-genome duplication within a species (autopolyploidy) or by combining chromosome sets from different species (allopolyploidy). Mechanisms include production of unreduced gametes and genome duplication. Polyploidy is especially common in plants and is associated with changes in cell size, morphology, and sometimes speciation. Crops such as bread wheat are polyploid; wheat is hexaploid (6n = 42) with a genome designated AABBDD.

Detection and study of euploidy employ cytogenetic and genomic methods, including karyotyping and flow cytometry, to determine chromosome number and DNA content. The concept of euploidy helps explain patterns of development, fertility, and evolution across taxa, highlighting differences between complete chromosome sets and aneuploid variation.