Chromosomal deletions, sometimes known as partial monosomies, occur when a piece or section of chromosomal material is missing. Deletions can occur in any part of any chromosome.
What does chromosome deletion mean?
The term “deletion” simply means that a part of a chromosome is missing or “deleted.” A very small piece of a chromosome can contain many different genes. When genes are missing, there may be errors in the development of a baby, since some of the “instructions” are missing.
What causes a chromosomal deletion?
Chromosomal deletions occur spontaneously at a low frequency, or are induced by treatment of germ cells (most efficiently, mature or maturing oocytes in the female, and postmeiotic spermatogenic cells in the male) with chromosome-breaking agents, such as acute radiation or certain chemicals.
Is chromosome deletion fatal?
If by inbreeding such a deletion is made homozygous (that is, if both homologs have the same deletion), then the combination is almost always lethal. This outcome suggests that most regions of the chromosomes are essential for normal viability and that complete elimination of any segment from the genome is deleterious.
What happens during chromosome deletion?
When parts of chromosomes are missing, a number of syndromes can occur. These syndromes are called chromosomal deletion syndromes. They tend to cause birth defects and limited intellectual development and physical development. In some cases, defects can be severe and affected children die during infancy or childhood.
Can chromosomal disorders be cured?
There is no cure for chromosomal disorders. chromosomal disorders affect a person’s genetic makeup. Because they actually create a change in a person’s DNA, there is no way to cure these disorders at this time.
What are the signs and symptoms of chromosomal abnormalities?
Symptoms depend on the type of chromosomal anomaly, and can include the following:
- Abnormally-shaped head.
- Below average height.
- Cleft lip (openings in the lip or mouth)
- Learning disabilities.
- Little to no body hair.
- Low birth weight.
- Mental and physical impairments.
What are the most common chromosomal disorders?
Some of the most common chromosomal abnormalities include:
- Down’s syndrome or trisomy 21.
- Edward’s syndrome or trisomy 18.
- Patau syndrome or trisomy 13.
- Cri du chat syndrome or 5p minus syndrome (partial deletion of short arm of chromosome 5)
- Wolf-Hirschhorn syndrome or deletion 4p syndrome.
How common are chromosomal disorders?
About 1 in 150 babies is born with a chromosomal condition. Down syndrome is an example of a chromosomal condition. Because chromosomes and genes are so closely related, chromosomal conditions are also called genetic conditions.