Monosomy is a genetic condition where an individual is missing one chromosome from a pair, resulting in only one chromosome instead of the usual two in diploid cells.
Essentially, instead of having the typical two copies of each chromosome, a person with monosomy has only one copy of a particular chromosome. This imbalance can disrupt normal development and function.
Understanding Monosomy
- Diploid Cells: Human cells are typically diploid, meaning they contain two copies of each chromosome, one inherited from each parent.
- Chromosome Pairs: Chromosomes exist in pairs (e.g., chromosome 1 from mom, chromosome 1 from dad).
- Monosomy Occurrence: Monosomy arises when one member of a chromosome pair is absent.
- Partial Monosomy: In some cases, an individual might have one complete chromosome from a pair and a portion of the other. This is called partial monosomy.
Consequences of Monosomy
The impact of monosomy depends heavily on which chromosome is affected. Monosomy is often lethal, especially for autosomes (non-sex chromosomes), because the absence of crucial genes can be devastating to development.
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Turner Syndrome: A well-known example of monosomy is Turner syndrome, where females are born with only one X chromosome (XO).
- Characteristics: Individuals with Turner syndrome often experience short stature, ovarian failure, and heart defects.
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Other Autosomal Monosomies: Monosomies involving other chromosomes are usually not compatible with life and result in miscarriage.
Diagnosis
Monosomy can be diagnosed through genetic testing, such as:
- Karyotyping: Analyzing the chromosomes under a microscope.
- Chromosomal Microarray Analysis (CMA): Detecting deletions or duplications of chromosomal segments.
- Prenatal Testing: Techniques like amniocentesis or chorionic villus sampling (CVS) can detect chromosomal abnormalities in a developing fetus.
In Summary
Monosomy is a chromosomal abnormality characterized by the absence of one chromosome from a pair. This condition can lead to significant health problems, depending on the specific chromosome involved, and is frequently lethal during early development.
