Chromosome abnormality

A chromosomal abnormality, chromosomal anomaly, chromosomal aberration, chromosomal mutation, or chromosomal disorder is a missing, extra, or irregular portion of chromosomal DNA. These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or more individual chromosomes are altered. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis. Chromosome abnormalities may be detected or confirmed by comparing an individual's karyotype, or full set of chromosomes, to a typical karyotype for the species via genetic testing.

Not to be confused with Chromatic aberration.

Almost every single cell in our body is made up of two of the 46 chromosomal pairs that make up our whole body. Chromosomes 23 are made up of 2 X or X and Y. The body's chromosomes hold all the information required for growth and development. Chromosomes abnormalities can be broadly divided into two categories: structural and numerical. Numerical abnormalities are entire chromosomes that are missing or more than a normal pair. A portion of a chromosome that has structural abnormalities may be absent, added, moved to another chromosome, or the opposite.

Sometimes chromosomal abnormalities arise in the early stages of an embryo, sperm, or infant. A mother's age is one of the many environmental factors that might lead to genetic mistakes. The implications of chromosomal abnormalities depend on the specific problem, they may have quite different ramifications. For example, Down syndrome is caused by an extra copy of chromosome 21. That can cause miscarriages, problems with growth or development, and illnesses.

The kind of chromosomal aberration is aneuploidy, which is an abnormal number of chromosomes produced by a missing chromosome.Rather than having monosomy, or only one copy, the majority of aneuploid people have trisomy, or three copies of one chromosome. Down syndrome is probably the best-known example of chromosomal abnormalities. In addition to trisomy 21, other primary chromosomal abnormalities observed in live newborns include Turner syndrome, Klinefelter syndrome.

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