Basics Of Genetics of Blood group Class presented by Dr Nippun Prinja(MD RESIDENT-1 IHBT) of SMS Medical college,Jaipur-302004 on 10/08/2015

1. Blood groupBlood group
geneticsgenetics
By:-Dr. Nippun Prinja

2. Covered under 6 headings:-Covered under 6 headings:-
1. Basic principles of Genetics
2. Blood group gene mapping
3. Blood group terminology
4. Inheritance of genetic trait
5. Population genetics
6. Blood group genomics

3. 1.)BASIC PRINCIPLES OF1.)BASIC PRINCIPLES OF
GENETICSGENETICS

4. • Chromosome-thread like structure visible during cell
division, 23 pairs,4 types.
Gene -segment of dna present on chromosome at
specific location(loci),basic unit of inheritence of any
trait including blood group antigens that is passed from
parents to offspring

5. • Alleles-gene at given locus of chromosome may exist in more
than one form.eg:-ABO gene locus is considered to have 3 alleles
A,B,O, with possible six genotypes(A/A,A/O,A/B,B/B,B/O,O/O)
• HOMOZYGOUS
• HETEROZYGOUS
• HEMIZYGOUS
• Genotype.
• Phenotype.

6. • ANTIGEN DENSITY- quantity of antigen expressed (more
seen in homozygous than in hetrozygous)
• DOSAGE EFFECT-homozygous red cells are more strongly
reactive with antisera than heterozygous
• POLYMORPHISM- occurrence of allelic variation in genome
mostly seen with Rh and MNS blood group system
• MUTATION-polymorphism that did not exist in biological parents
OR difference in allele that lead to permanent change in DNA sequence.

7. 2.)BLOOD GROUP GENE2.)BLOOD GROUP GENE
MAPPINGMAPPING
Gene locus is assigned by gene
mapping.
Duffy BG was 1st
to be assigned to a
chromosome.
34 blood groups are assigned to
their chromosomes.
Traditional methods:- G & Q
banding
Advance methods:-FISH &
chromosome walking technique

8. 3.)BLOOD GROUP3.)BLOOD GROUP
TERMINOLOGYTERMINOLOGY
In 1980 ISBT established
this uniform nomenclature.
Each BG system has been
given a particular
alphanumeric terminology.
Each antigen is also given
number
Terminology takes into
account guidelines given by
HUGO

9. 4.)INHERITANCE OF GENETIC4.)INHERITANCE OF GENETIC
TRAITTRAIT
A)AUTOSOMAL DOMINANT

10. B)AUTOSOMAL RECESSIVE

11. C) SEX LINKED DOMINANT
INHERITANCE

12. 4)SEX LINKED RECESSIVE INHERITANCE

13. INDEPENDENT SEGREGATION-Sepration of homologous
chromosomes .
INDEPENDENT ASSORTMENT-alleles are inherited
independently from each other OR one allele inheritance does not influence
another allele
LINKAGE-physical association between two genes located on same
chromosome and inherited together.
(Eg:-RHD and RHCE antigens on chromosome 1) Linkage between Lutheran(lu)
and ABH secretion was 1st
recognized example of autosomal linkage in humans
CROSSING OVER-exchange of genetic material b/w homologous
chromosome pairs .

14. 5.)Population genetics5.)Population genetics
 Study of distribution pattern of genes.
 Uses- 1) phenotype prevelance
2)calculation of antigen negative phenotype
3)allele frequency
HARDY WEINBERG LAW
 VALID IN STABLE AND LARGE POPULATION WHERE GENE
FREQUENCIES REACH EQUILIBRIUM AND MATING IS RANDOM
 Used for:-
1)estimation of frequency of particular alleles.
2)estimation of frequency of particular genotype.

15. APPLICATION IN BLOOD GROUPAPPLICATION IN BLOOD GROUP
GENETICSGENETICS

16. 6.)BLOOD GROUP GENOMICS6.)BLOOD GROUP GENOMICS
 HEMAGGLUTINATION HAS LIMITATIONS
 NEWER DNA TECHNIQUES(PCR,RFLP,GEL ELECTROPHORESIS)
To predict phenotpe
1)After recent multiple transfusions.
2)distinguish an alloantibody from autoantibody
3)when patients red cells are coated with immunoglobulin
4)after allogenic stem cell transplantation
5)resolve discrepencies Eg:A B and Rh
6)mass screening to increase antigen negative population