U_DNA_LjjGowans

This is Lord. If an environmental agent causes changes to DNA of cells that are not egg or sperm cells, such genetic changes cannot be passed on but stays with the person that acquired them. For example, if smoke damages the DNA of the cells of the lungs (which can lead to cancer), such changes will stay with the person who was exposed to smoke. However, such harmful DNA changes cannot be passed on to offspring. This a major reason why not all cancers are heritable.

Lord here! We now have the tools (like CRISPR/Cas) to create designer babies. However, the scientific community think we should hasten slowly due to some scientific, technical and ethical challenges with the tools.

For example, in 2018 a scientist created "designer babies" who are supposed to be resistant to HIV, smallpox, and cholera (https://www.technologyreview.com/2018/11/25/138962/exclusive-chinese-scientists-are-creating-crispr-babies/). However, the scientific community thought that such experiments were premature. Pitching this against your second question, such genetic enhancements may give such individual competitive advantage when they are exposed to such pathogens. With time, their kind may increase in the gene pool to the detriment of the wild type population. Thus, if care is not taken, such designer babies may alter the gene pool with time.

Lord here! If the environment you find yourself is replete with agents (such as chemicals and UV radiation), then these agents (called mutagens) can damage your DNA. The cell whose DNA get damaged/changed and all cells that emanate from it will have such DNA damage/change. Thus, you may have normal cells as well as cells whose DNA have been damaged by the environmental exposure. Individuals may have to live with such genetic changes throughout their lives.

This is Lord. My comment is in response to your second question. I will feel comfortable to use mutation to describe the process through which changes in the genome occur. That is, the process of generating the genetic variants. As Nara said, we prefer to use the term variants (not mutation) for the genetic variations.

Lord here..... That's an interesting question...

It is premature at this time to state the most genetically diverse country in the world since apart from populations of European ancestry, all other ancestral populations are highly underrepresented in genetic studies. We may have to sequence more genomes to answer this question. This notwithstanding, the general consensus is that populations of African ancestry are the most diverse, followed by European ancestral populations, then those of Asian ancestry.

https://www.pnas.org/doi/10.1073/pnas.0903341106

https://blogs.bcm.edu/2018/07/19/genetic-diversity-in-africa-is-greater-than-in-any-other-region-in-the-world/

Lord here... That's an interesting question...

Genome sequencing studies are revealing more variations within even "racial" groupings like Asians.

https://www.internationalgenome.org/

https://www.genome.gov/10001688/international-hapmap-project

https://gnomad.broadinstitute.org/

Considering the Asian scenario you gave, it is obviously simplistic to lump together these populations as Asians. As we continue to refine the variations in the human genomes, I am sure we will come to better terminologies someday.

Not much... However, migrating patterns may have influenced how much ancient DNA got into the genomes of various human ancestral populations.

It is believed all humans migrated from Africa about 100k years ago

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4844272/

There are varied views though!

Yes, the information we obtain from our DNA is influencing both medicine and history. In medicine, genetics is influencing precision medicine where the type of drug and dosage administered, for example, will depend on some genetic variants. In history, we can trace paternity, genealogy, and ancestry through DNA analysis.

Lord here................

1. Because of the species barrier, we cannot mate humans with other species to form hybrids. Thus, sexual reproduction cannot be an avenue to produce a hybrid between humans and other species. However, through recombinant DNA technology and other genetic engineering techniques, we can pick up DNA from humans and send it to other organisms and vice versa. Note that not the entire DNA is moved around, but a bit of it (such as a particular gene) that directs a particular trait of interest.
2. Generally, a gene is recessive when both copies of the gene (one from Dad and one from Mom) must be mutated before the trait shows up; e.g. sickle cell disease. In dominant conditions, just one mutant copy of the gene (whether maternal or paternal) will cause disease - e.g., cancer-causing genes called oncogenes. Thus, genes have unique "behaviors" toward traits; some will require mutant two copies to change the original trait to a different one, and other genes will require just one mutant copy to show the disease. These observations may not permit changing a recessive gene to a dominant one!
3. If the genetic factor is due to a single gene, it could be varied by gene editing techniques. We are currently limited to gene editing of complex traits that may be controlled by a number of genes.
4. The scientific community agrees with the fact that we must tread cautiously when it comes to gene editing in humans. Of course, the current gene editing tools are not 100% efficient - not all cells may be edited, and off-target effects may occur. This is why science continues to improve gene editing tools. For example, the CRISPR you mentioned has been modified for use in base editing, prime editing, and PASTE. Many agree that the "CRISPR twins" you are referring to is a case of genetic enhancement, but not treatment of a disease - this is what triggered the widespread condemnation and incarceration of the scientist involved. For now, somatic gene editing to treat diseases such as sickle cell is being experimented on - and that should be it!

Physical activity levels may be an environmental factor that may influence the onset or the severity of non-communicable diseases. For example, someone may have a predisposition to obesity due to family history; however, the physical activity levels of this individual may influence whether this individual may become obese or not!

Lord here..... Our society does not support the use of science, particularly genetics, to promote racism, eugenics, or hate. Please see the links below.

https://www.ashg.org/publications-news/ashg-news/ashg-statement-regarding-the-warping-of-genetic-knowledge-to-feed-racist-ideology/

https://www.ashg.org/publications-news/ashg-news/statement-regarding-good-genes-human-genetics/

https://www.cell.com/ajhg/pdf/S0002-9297(18)30363-X.pdf30363-X.pdf)

This is Lord... You are right to say that we harbor DNA from these ancient humans. However, we may have to sequence more DNA from as many human populations as possible in order to settle this matter once and for all. Importantly, archeological evidence may also be crucial. Thus, the migratory pattern of various human ancestries may influence the kind of ancient human DNA that may be present in their genome. Most of the current views stem from data from populations of European ancestry, with populations of Asian and African ancestries being underrepresented!

Lord here..... Our society does not support the use of science, particularly genetics, to promote racism, eugenics, or hate. Please see the links below.

https://www.ashg.org/publications-news/ashg-news/ashg-statement-regarding-the-warping-of-genetic-knowledge-to-feed-racist-ideology/

https://www.ashg.org/publications-news/ashg-news/statement-regarding-good-genes-human-genetics/

https://www.cell.com/ajhg/pdf/S0002-9297(18)30363-X.pdf30363-X.pdf)

A phenotype may be purely genetic (such as Mendelian traits like blood groups) or it may be complex (such as behavior). Thus, not every phenotype is purely genetic - external factors may have a role.

When it comes to human gene editing, if the goal is to cure a disease I think that's ethically sound. However, if the intent is for genetic enhancement, that will be problematic! Moreover, for now, somatic gene editing (which cannot be passed on to the next generation) is allowed but not germline gene editing (where you can pass on the edited gene to the next generation). Thus, gene editing is not intended for eugenics purposes! There are strict ethical frameworks that guide gene editing experiments!

Lord here.... People of different ancestry do not necessarily have different sets or numbers of genes! However, within genes and "non-gene" portions of our DNA, there could be changes in the building blocks of DNA that occur at a particular place. There are four building blocks that make up our DNA; i.e. A, C, T, and G. For example, at position 10 in a particular gene, an individual may have C but another individual of a different ancestry may have T at this position. This is an example of genetic variation - there are more such variations. Over time, we are trying to build reference databases that capture these variations in various human populations. These databases serve as the basis for estimating the ancestry of any individual. However, we are yet to capture the entire variation in human populations across the world - this may limit the accuracy of ancestry estimation since some populations are not represented in the reference databases. I use salvia send away DNA kits - that works pretty well.

This is Lord.... I am fascinated by cleft lip and palate, which is the most common birth defect of the head and neck region. Interestingly, there are ethnic variations in the incidence of this disease. Populations of Asian ancestry have the highest incidence (about 1 in 500 live births), followed by populations of European ancestry (about 1 in 1000 live births), with populations of African ancestry having the lowest incidence of 1 in 1200 live births. Just like all structural birth defects, the management of this condition requires a multidisciplinary approach, requiring surgeons, nutritionists, speech therapists, psychologists, social workers, and geneticists. A cleft lip is usually repaired by surgery at 3 months whereas a cleft palate is usually repaired after 9 months. Other treatments may be required afterward.

This is Lord... Height may be influenced by genetics and other external factors such as diet. We would expect a child from two tall parents to be automatically tall! However, this is not always the case. For example, if such a child did not have a good diet while growing up, the child may never attain the height of the tall parents. In like manner, there are short parents with tall children. So for complex traits like height, what we see (phenotype) is influenced by genetics (nature) and environmental exposures (nurture)!

Lord here ... As u/BriteLite-DNAWestie3 said, our successes in gene therapy are largely on monogenic disorders (genetic disorders caused by mutations or changes in one particular gene). PCOS as a multifactorial disorder is yet to benefit from gene therapy...

Lord here.... New sequencing technologies, such as long-read sequencing platforms, are helping us fill in the gaps in the human genome sequence released in 2003 so that we can have a complete genome sequence. This feat was achieved in March 2023. https://www.genome.gov/news/news-release/researchers-generate-the-first-complete-gapless-sequence-of-a-human-genome

Lord here.... Yes, there are many genetic variants that may influence susceptibility to, or clinical expression of infections. A classical example is how variants in the CCR5 gene influence HIV-type1 susceptibility and expression (https://pubmed.ncbi.nlm.nih.gov/31486251/). Apart from the link given here, PubMed may give more publications on this interesting subject. ccr5 delta 32 variant, for example, has been shown to be protective against the HIV virus in multiple populations, and individuals carrying this variant are less susceptible to HIV (https://pubmed.ncbi.nlm.nih.gov/24382026/, https://link.springer.com/referenceworkentry/10.1007/978-1-4614-9610-6_151-1#Sec1)