Question

Identify the different types of chromosomal abnormalities that can lead to disease (e.g. insertions) and in a sentence or two, describe a disorder associated with one of these aberrations

Answer 1

Chromosomal abnormalities

Any change in the normal karyotype of an organism is called chromosomal abnormalities. Chromosomal abnormalities result by a change in the number of chromosomes or a change in the structure of chromosomes. Most of the chromosomal abnormalities produce genetic disorders or diseases. Chromosomal abnormalities may result by errors during cell division, errors during gamete formation, errors during embryo development, inherited from parents etc.

  Chromosomal abnormalities may be numerical or structural. Numerical abnormalities occur by change in the chromososme number. It may be Aneuploidy or Polyploidy. Aneuploidy means variation in the number of particular chromosomes with in a set. It includes trisomy (2n + 1), tetrasomy (2n + 2), monosomy (2n-1), nullisomy (2n-2) etc. Polyploidy have more than two sets of homologous chromosomes. It may be triploid (3n), tetraploid (4n), pentaploid (5n) etc.

Structural abnormalities takes place when a part of DNA is missing from the chromosome or added to the chromosome or re arranged. Main structural abnormalities includes Deletion, Duplication, Inversion, Translocation etc. Deletion means the loss of a part of chromosome. Duplication means a part of chromosome is repeated. In insertion, a part of a chromosome get inserted into another chromosome. Translocation means a portion of chromosome move to a different part of the same chromosome or to a different chromosome. Inversion means a particular part of a chromosome is oriented in reverse direction ie, reinserted.

Disease associated with chromosomal abnormalities

Down syndrome - trisomy 21

Turners syndrome - Monosomy

Edward's syndrome - Trisomy 18

Patau's syndrome - Trisomy 13

Cri - du - chat syndrome - deletion

Mantle cell lymphoma - translocation

Fragile X- syndrome - Duplication

Klinefelter's syndrome - trissomy

Edward's Syndrome -  it is also called trisomy 18. It is due to the presence of an extra copy of chromosome 18. The symptoms associated with the disease includes delayed development, feeding ad breathing difficulty, intellectual disability, intestine project outside the body etc.