8/8/2019 Inheritance of Blood Types

1/3

CASE 4 SEM 3

Inheritance of Blood Types

Blood type inheritance categorized in co dominance Occurs when alternative alleles are present in the genotype and fullyobserved in the phenotype

E.g. ABO blood grouping system, where a single gene locus features multiple alleles- IA,IB, and i. Individuals carrying alleles for both A and B express both in the phenotype AB

These charts show the possible blood type results for offspring.

Blood TypeMothers's Type

O A B AB

Fathers'Type

O O O, A O, B A, B

A O, A O, A O, A, B, AB A, B, AB

B O, B O, A, B, AB O, B A, B, AB

AB

A, B A, B, AB A, B, AB A, B, AB

8/8/2019 Inheritance of Blood Types

2/3

CASE 4 SEM 3

RH system :

Rh system is so named because it was first discovered in the blood of rhesusmonkey.

There are six common types of Rh antigen (agglutinogen) C,D,E, c,d,e. The type D antigenic is more antigenic.

Any one who have D antigenRh +ve

Person who does not have D antigenRh ve. About 85% of all population are Rh +ve

Recall:

Alleles are different forms of a gene.

A gene is a stretch of DNA that codes for a protein that may result ina trait.

An individual inherits an allele for each gene from each parent.

Dominant Alleles the phenotype is always expressed

Recessive Alleles- the phenotype is only expressed when there areno dominant alleles

Codominant both phenotypes are expressed

Genotype is the specific allele makeup. (Expressed as the two alleleletters)

Phenotype is the outward physical appearance, in the case of thislab, the blood type

The Rh system is actually much more complicated than the ABO system because thereare more than 30 combinations possible when inherited, however for general usage, theRh proteins are grouped into two families - either positive or negative.

As with the ABO system, there is a dominant allele which happens to be the positivefamily. This means that the genetic pairs that can exist in humans are as follows:

Genetic makeup Blood type

++ Rh positive

+- Rh positive

-- Rh Negative

The same inheritance rules apply as on the previous page:

Parents' Rh typesPossible allelecombinations

Possible Rh in the children

Rh FactorMother's Type

Rh + Rh -

Father'sType

Rh+

Rh +, Rh - Rh +, Rh -

Rh - Rh +, Rh - Rh -

http://www.paternityangel.com/general_info_zone/Glossary.htm#Ahttp://www.paternityangel.com/general_info_zone/Glossary.htm#A

8/8/2019 Inheritance of Blood Types

3/3

CASE 4 SEM 3

Both + ++ & ++ ++ positive

Both + ++ & +- ++ or +- positive

Both + +- & +- ++ or +- or --poitive

ornegative

Both - -- & -- -- negative

One + & One - ++ & -- +- positive

One + & One - +- & -- +- or --poitive

ornegative

Rh negative children can have parents that are either Rh positive or Rh negative.

If both parents are Rh negative then the children will be Rh negative.