Question

What is a Genetic Marker? What are types of the genetic markers in the plasma?

Answer 1

• In the human genome, the most common types of markers are SNPs, STRs, and indels.
• The SNPs affect only one of the basic building blocks—adenine (A), guanine (G), thymine (T), or cytosine (C)—in a DNA segment.

GENETIC MARKERS IN PLASMA (SERUM PROTEIN):

• Both plasma and serum, the yellow fluid portion of blood, contain several soluble proteins. These proteins can easily be separated from each other by electrophoresis.
• Here a few of them will be discussed below:

1.Haptoglobin (Hp):

• Haptoglobin is alpha-globin.
• It combines with hemoglobin in the plasma.
• But by electrophoresis, it can easily be identified.
• There are essentially three different types of haptoglobin, such as, Hp 1-1, Hp 1-2 and Hp 2-2, in which two genes, namely, Hp1 and Hp2 are involved. Hp 1-1 and Hp 2-2 are homozygous, while Hp 1-2 is heterozygous for Hp1 and Hp2.
• These two are codominant autosomal alleles.
• The two alleles follow Mendelian principle of inheritance.
• In African populations many individuals are met with in whose serum haptoglobin is absent.
• They are called ahaptoglobinemic (HpO). In European populations such persons are not reported.
• A large number of populations have been investigated for haptoglobin.
• In dealing with the distribution of haptoglobin the incidence of Hp1 gene is taken into account.
• Among some populations of Central and West Africa as well as of Central and South America Hp1 gene occurs in very high frequency.
• The worldwide distribution of this gene indicates that its frequency rises from India to North America through Siberia on one hand, and to western and northern Europe on the other.
• Again, its frequency increases from North America to the equatorial belt of South America.
• In Africa from the equatorial regions its frequency decreases towards North as well as South Africa.

2.Transferrin (Tf):

• Transferrins are part of beta globins.
• They have chemical property of binding iron.
• The important function of these proteins is to transport oxidized iron to and from the bone marrow and other tissues.
• Several molecular varieties of transferrin have been identified.
• Each one is non dominant autosomal allele located in the same locus.
• The most common is the C type (TfC) in all populations of the world.

3. Albumin:

• Albumin is a serum protein. It shows several polymorphic varieties, which have been reported from different populations.

Others:

• In addition to the above mentioned 3, there are several serum proteins, e.g., Group specific component (Gc). Alkaline phosphate, Ceruloplasmin, Gm system, Inv system, etc.

Genetic Marker: The specific sequence of DNA at a known location on a chromosome is known as the Genetic Marker.