A hypotriploid cell line is a type of cell line that contains fewer than three copies of each chromosome. In other words, the cell line has a chromosome number that is less than the normal diploid (2n) number of 46 chromosomes, and less than the triploid (3n) number of 69 chromosomes.

A hypotriploid cell line may arise naturally due to errors in cell division or other genetic abnormalities, or it may be deliberately generated through genetic manipulation or exposure to mutagenic agents. The characteristics of a hypotriploid cell line can vary depending on the specific chromosomal abnormalities present, but may include altered gene expression, changes in cell growth and division, and increased susceptibility to certain diseases or environmental factors.

Hypotriploid cell lines are relatively rare compared to other types of aneuploid cell lines (i.e. cell lines with an abnormal number of chromosomes), and may have implications for the use of the cell line in research or therapeutic applications. It is important to characterize the chromosomal abnormalities present in a hypotriploid cell line in order to better understand its properties and potential limitations.