What Causes Chromosome Deletions?

The process of meiosis in human beings results in the production of sperm cells and egg cells. These cells have 23 chromosomes each. When the sperm fertilizes the egg, it results in a zygote that normally contains 46 chromosomes. However, sometimes each egg and each sperm may not carry the full complement of 23 chromosomes each, resulting in missing chromosomes. This could come about due to chromosome deletions.

Chromosome Deletion

• Sometimes, a chromosome is missing some of its genetic information. This is known as chromosome deletion. The genetic material could be missing at the tip of the chromosome, in a form of deletion called terminal deletion. Or the genetic material could be missing from inside the chromosome.

Results of Deletion

• If a person has chromosomes with some deleted genetic material, it could create imbalances in his genetic material that could result in disorders. While some people have a deletion that impacts a big part of their chromosome, it is more common to experience smaller deletions.

Spontaneous Mutation

• A chromosome deletion could come about as a result of a spontaneous mutation without any other influence acting on it. This is a result of imperfect internal processes. During the process of meiosis, for instance, a deletion could come about if a piece of DNA breaks up and then rejoins, leaving out some genetic information.

Induced Mutation

• Another process that impacts chromosomes is induced mutation. This is when an outside agent produces the change in the DNA. This could happen as a result of interactions with chemicals such as nitrous acid, which act on the chemical bases of DNA. Exposure to radiation from sources such as X-rays could damage DNA as well. Exposure to ultraviolet radiation could come from the sun or tanning lamps.