Mutations in Humans: Calculating Human Gene Code Change Rate

  • Thread starter Thread starter heliocentricprose
  • Start date Start date
Click For Summary

Discussion Overview

The discussion centers around the mutation rate of the human genome across generations, exploring how to calculate the percentage of genetic changes and the implications of various mutation types. Participants reference both theoretical models and empirical data to understand the complexities involved in measuring mutation rates in humans.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the average percentage of human gene code changes per generation and expresses uncertainty about calculating mutation rates.
  • Another participant presents a formula for mutation rate, alpha=\frac{h}{N}, and discusses challenges in measuring mutations due to the high rate of fatal spontaneous mutations during embryo development.
  • Several participants reference a paper that reports a mutation rate of 10^-5 per generation for hemophilia and suggest that comparisons with chimpanzees indicate rates around 10^-8.
  • There is a discussion about what these mutation rates represent, with one participant clarifying that they refer to nucleotide changes for single alleles.
  • One participant estimates that with approximately 100,000 genes, the overall mutation rate could be approximated as one point mutation per generation across the human genome, while noting the limitations of this assumption.
  • Participants acknowledge the existence of other mutation types, such as crossovers, deletions, and insertions, which complicate the understanding of the true mutation rate.
  • Historical data is mentioned regarding conception and spontaneous abortion rates, suggesting that many mutations may not be observed in live births.

Areas of Agreement / Disagreement

Participants express uncertainty and highlight multiple competing views regarding the mutation rate and the challenges in accurately measuring it. There is no consensus on the exact mutation rate or the implications of the data presented.

Contextual Notes

Limitations include the difficulty in accounting for all mutations due to the diploid nature of humans, the ethical concerns surrounding the analysis of premature births, and the reliance on historical data that may not reflect current rates.

heliocentricprose
Messages
29
Reaction score
0
On average, what percent of the human genecode changes each generation? I know there's somesort of mutation rate, but I haven't studied biology for several years and I'm not exactly sure how to calculate it.
 
Biology news on Phys.org
The mutation rate for a generation of cells is given as
[tex]alpha=\frac{h}{N}[/tex]
Where h is the number of mutation observed and N is the total number of cell divisions.

If you tranlsate that to humans, you are interested in the rate as a function of the number of new mutations showing up in the next generation. However, there are lots of problems with this. A large number of spontaneous mutations are fatal to embryo development, for example. So unless you analyzed every premature birth for new defects, you'd miss them. This isn't practical or ethical.

And I have no idea how you could find all mutations - we're diploid, so a recessive mutation has a large probability of not displaying a trait.
 
jim mcnamara said:

"calculated that the per locus rate of mutation for hemophilia in humans is 10^-5 per generation"

"Comparisons of pseudogenes and of synonymous sites between humans and chimpanzees have suggested mutation rates on the order of 10^-8"

10^-5
10^-8

What do these numbers represent? Base pair substitutions, mutation events?
 
Nucleotide changes - for a single allele (DNA sequence that codes for one enzyme). eg. a Thymine becomes an Adenine, for example.
 
So this means there are 1/100000000 nucleotide changes per generation?
 
For one allele, or "one gene". Humans have circa 100,000 genes with sometimes hundreds of alleles (possible gene variations for a given locus).

[lousy assumption alert]

So, multiply your number times 100,000 and you have a guesstimate of the mutation rate in humans per generation. Since 10^-5 times 10^5 =1
then the mutation rate over all genes - based on the paper - in humans is about one point mutation (that's what a nucloetide change is) per generation somewhere in all of the human genome.

[/lousy assumption alert]
There are other types of mutations, crossovers, deletions, insertions etc.
(a lot of which are fatal) so it's hard to know the true rate based on looking at only live born people. I do know that Thompson & Thompson Medical Genetics indicates that for 100 live male births there are ~130 conceptions. The spontaeous abortion rates for female fetuses is lower.
(This is very old data)
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
4K
Replies
4
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 2 ·
Replies
2
Views
5K
Replies
1
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
Replies
4
Views
3K
Replies
20
Views
5K
Replies
12
Views
6K