G H Hardy and Wilhelm Weinberg are the namesakes of the legislation.
They were pioneers in the mathematical illustration of this principle, which is also known as the Hardy–Weinberg equilibrium, theorem, law or model, among other names.
It was the core focus of Hardy’s thesis to disprove the belief that was prevalent at the time that a dominant allele has the tendency to rise in frequency on its own accord.
In today’s world, the degree of ambiguity around selection and dominance is not particularly noteworthy.
To examine population stratification and other types of non-random mating, the Hardy-Weinberg genotype frequency tests are now being used to evaluate the genotype frequencies of individuals. Inbreeding is the most common cause of non-random mating in a population. It results in an increase in the homozygosity of all genes in the population.
Assumptions of Hardy–Weinberg Equilibrium
1.Organisms are diploid (have two copies of DNA).
2.Only sexual reproduction takes place.
3.Generations do not overlap with one another.
4.Mating is a completely random process.
5.The population size is virtually limitless.
6.Allele frequencies are the same in both sexes, save for one.
7.There is no migration, gene flow, mixing, mutation, or selection occurring in the population.
Violations of the Hardy– Weinberg assumptions can lead to deviations from expectations in a variety of situations.
The consequences of this for the general population are dependent on the assumptions that have been violated.
The Hardy-Weinberg rule
Hardy’s statement begins with a recurrence relation for the frequencies p, 2q and r which is followed by a recurrence relation for the frequencies p, 2q and r.
Fundamental notions in probability, notably independence and conditional probability, are the foundation for these recurring relations.
The Hardy Weinberg Equation is represented as:
p2 + 2pq + q2
Application of Hardy-Weinberg law
It should be noted, however, that the Hardy-Weinberg equilibrium model does not hold true for haploid pathogens.
It is one of the assumptions of this law that one of the assumptions is violated if a population is not discovered in Hardy-Weinberg equilibrium in the first place.
This indicates that selection, non-random mating, or migration has had an impact on the population, and in this situation tests are conducted and theories are proposed in try to determine the reasons for the population’s non-equilibrium.
I. Complete Dominance
There is a possibility of detecting allele frequencies in the presence of total dominance when Hardy-Weinberg equilibrium prevails and it is not possible to distinguish between two genotypes.
It is possible to determine the allele frequencies from the frequencies of individuals with recessive phenotype aa if two genotypes AA and Aa have the same phenotype as a result of total dominance of A over a.
A recessive allele’s frequency of occurrence should be proportional to the square of the frequency of occurrence of the individual in question.
II. Alleles in a number of locations
The Hardy Weinberg principle allows for the calculation of genotypic frequencies at a locus that contains more than two alleles, as is the case for the ABO blood types,
for example. IA, IB, and IC all contain three alleles with p,q and r frequencies, respectively.
The sum of the frequencies of the alleles in IA, IB, and IC is one; the sum of the frequencies of the other alleles is one.
Assuming random mating, the genotype of a population can be calculated using the formula (p+q+r).
III. Linkage Disequilibrium
Consider the case of two or more alleles on the same chromosome, or two or more alleles at two distinct loci with two or more alleles.
The frequency of allelic combinations reaches equilibrium as a result of genetic exchange by recombination occurring at regular time intervals between two syntenic loci and occurring at two syntenic loci.
IV. Frequency of Harmful Recessive Alleles in the Population
Additionally, the law can be used to predict the prevalence of heterozygous carriers of dangerous recessive alleles in heterozygous individuals.
If two alleles, A and a, are found at an autosomal locus with p and q frequencies, respectively, and p + q = 1, then the genotypes AA, Aa, and aa will have the following frequency: p2 + 2pq + q2
If two alleles, A and a, are found at an autosomal locus with p and q frequencies, respectively, and p + q = 1,
then If the aa genotype has a tendency to express a phenotype that is deleterious,
such as cystic fibrosis, then the proportion of affected persons in the population will be q2, and the recessive allele frequency of the heterozygous carrier will be 2pq in the population.
Conclusion
The law implies that, given a known frequency of distinct alleles in a population, it is possible to predict the expected frequencies of genotypes in a population under a specific set of assumptions that are limited in scope.
Geneticists can utilise the Hardy-Weinberg law to determine the probability of human matings that will result in the birth of children with physical or mental abnormalities.
Sometimes important in detecting if the number of dangerous mutations in a population is increasing as a result of radiation from industrial processes, medical treatments and nuclear fallout is the law of large numbers.
If the premise of random mating is violated, this population will not have Hardy Weinberg proportions, as is the situation in the real world.