You can potentially live without one sex chromosome (an X or a Y), but generally not without any other chromosome.
While having the typical number of chromosomes (46) is crucial for healthy development, there are instances where individuals survive with an abnormal number. These cases, however, are almost always associated with significant health challenges.
The most tolerated chromosomal abnormality involving missing chromosomes involves the sex chromosomes:
- Turner Syndrome (Monosomy X): Females with Turner Syndrome have only one X chromosome (XO). They can survive, but often experience a range of health issues including short stature, infertility, and heart defects.
The tolerance for missing sex chromosomes stems from a process called X-inactivation. In females (XX), one X chromosome is randomly inactivated in each cell, effectively reducing the dosage of X-linked genes. Therefore, a female with only one X chromosome doesn't have a drastic imbalance. Males (XY) only have one X chromosome normally, so the absence of a Y chromosome is generally less detrimental than the absence of an autosome (non-sex chromosome).
Missing any other chromosome (an autosome) is almost always fatal. These conditions are usually incompatible with life because each autosome carries genes essential for development and function. The loss of these genes disrupts vital processes, preventing the embryo from developing fully. While some autosomal monosomies (missing one copy of an autosome) might result in a pregnancy, they almost always end in miscarriage early on.
In summary, while survival is possible with a missing sex chromosome (X or Y), missing any other chromosome is generally not compatible with life.
