Hardy-Weinberg equilibrium - (Apr/24/2008 )
Several studies and literature on SNP check if the genotypes to study follow the Hardy-Weinberg equilibrium. What is teh point of doing this?
The equilibrium, proposes that the frequency of alleles and genotypes in a population will remain constant from generation to generation if the population is stable and in genetic equilibrium. My question may sound studpid but can someone pls help me understand the concept: If the genotypes remain constant, then how can we have SNPs, b/c they are polymorphisms.
What does it mean that the genotype frequencies in a population remain constant?
Thanks
SF
The equilibrium, proposes that the frequency of alleles and genotypes in a population will remain constant from generation to generation if the population is stable and in genetic equilibrium. My question may sound studpid but can someone pls help me understand the concept: If the genotypes remain constant, then how can we have SNPs, b/c they are polymorphisms.
What does it mean that the genotype frequencies in a population remain constant?
Thanks
SF
You check if it is in equilibrium or not. If not (all natural populations are not, but you have now a standard, an ideal population to compare with) several reasons may attribute to it, drift, mutations, bottlenecks, migration etc., all the forces that promote evolution. Its one starting point for further statistics as F-statistics, heterozygote frequencies, etc.
The equilibrium, proposes that the frequency of alleles and genotypes in a population will remain constant from generation to generation if the population is stable and in genetic equilibrium. My question may sound studpid but can someone pls help me understand the concept: If the genotypes remain constant, then how can we have SNPs, b/c they are polymorphisms.
What does it mean that the genotype frequencies in a population remain constant?
Thanks
SF
I'M LOST
Hi Sarwat,
Hardy-Weinberg equilibrium simply means that allele frequencies in a population are as predicted. If you know how many alleles there are and what their frequencies are, you can calculate the expected frequencies of all possible homozygotes and heterozygotes. If the observed homo/heterozygote frequencies approximate the expected frequencies, then the population is deemed to be in H-W equilibrium. This equilibrium indicates that there are no significant influences acting on the population (hobgoblin listed a few) to upset the equilibrium. For example, a common (high frequency) allele is expected to exist in x homozygotes and y heterozygotes, as predicted mathematically, but if you observe that there are fewer heterozygotes and more homozygotes than expected, then something is happening in the population to cause this deviation from equilibrium. Remember though, H-W equilibrium is a mathematical construct describing a hypothetical ideal population. Natural populations can sometimes approximate equilibrium but rarely precisely achieve it.
Hardy-Weinberg equilibrium simply means that allele frequencies in a population are as predicted. If you know how many alleles there are and what their frequencies are, you can calculate the expected frequencies of all possible homozygotes and heterozygotes. If the observed homo/heterozygote frequencies approximate the expected frequencies, then the population is deemed to be in H-W equilibrium. This equilibrium indicates that there are no significant influences acting on the population (hobgoblin listed a few) to upset the equilibrium. For example, a common (high frequency) allele is expected to exist in x homozygotes and y heterozygotes, as predicted mathematically, but if you observe that there are fewer heterozygotes and more homozygotes than expected, then something is happening in the population to cause this deviation from equilibrium. Remember though, H-W equilibrium is a mathematical construct describing a hypothetical ideal population. Natural populations can sometimes approximate equilibrium but rarely precisely achieve it.
Thank you very much for your clarification. Truly appreciated. I'm new to SNP analysis and gene studies.
Hardy-Weinberg equilibrium simply means that allele frequencies in a population are as predicted. If you know how many alleles there are and what their frequencies are, you can calculate the expected frequencies of all possible homozygotes and heterozygotes. If the observed homo/heterozygote frequencies approximate the expected frequencies, then the population is deemed to be in H-W equilibrium. This equilibrium indicates that there are no significant influences acting on the population (hobgoblin listed a few) to upset the equilibrium. For example, a common (high frequency) allele is expected to exist in x homozygotes and y heterozygotes, as predicted mathematically, but if you observe that there are fewer heterozygotes and more homozygotes than expected, then something is happening in the population to cause this deviation from equilibrium. Remember though, H-W equilibrium is a mathematical construct describing a hypothetical ideal population. Natural populations can sometimes approximate equilibrium but rarely precisely achieve it.
Thank you very much for your clarification. Truly appreciated. I'm new to SNP analysis and gene studies.
Is there a software that can calculate the Hardy-Weinberg equilibrium, chi square test and Kaplan-Meier test all in one?
Hardy-Weinberg equilibrium simply means that allele frequencies in a population are as predicted. If you know how many alleles there are and what their frequencies are, you can calculate the expected frequencies of all possible homozygotes and heterozygotes. If the observed homo/heterozygote frequencies approximate the expected frequencies, then the population is deemed to be in H-W equilibrium. This equilibrium indicates that there are no significant influences acting on the population (hobgoblin listed a few) to upset the equilibrium. For example, a common (high frequency) allele is expected to exist in x homozygotes and y heterozygotes, as predicted mathematically, but if you observe that there are fewer heterozygotes and more homozygotes than expected, then something is happening in the population to cause this deviation from equilibrium. Remember though, H-W equilibrium is a mathematical construct describing a hypothetical ideal population. Natural populations can sometimes approximate equilibrium but rarely precisely achieve it.
Thank you very much for your clarification. Truly appreciated. I'm new to SNP analysis and gene studies.
Is there a software that can calculate the Hardy-Weinberg equilibrium, chi square test and Kaplan-Meier test all in one?
Not that I'm aware of.