timeuser84 said:
Hi again. About over 5 years ago I was reading something on the net about a certain human gene that is unique and rare in humans called the freak gene, super human, or slow turtle gene. Is there another name for it and does this gene exist in humans? How do I find out if I have this gene or these genes? If i don't have that genes than how do i find out what genes and type of genes i have?
All humans have the same set of genes. What varies between humans is particular variants of genes called
alleles. Inherticance of particular alleles of genes can cause inheritance of certain traits. For example, there are two alleles of the gene ABCC11 that help determine whether one has
dry or wet earwax; if you inherit at least one copy of the first allele, you will have wet earwax, while if you inherit two copies of the second allele you will have dry earwax. In many cases, alleles are non-functional variants of a particular gene and inheriting two copies of the non-functional alleles leads to genetic diseases. One example of this are non-functional variants of the CFTR gene, which act as recessive alleles for the disease cystic fibrosis.
Most of the traits that we care about, however, are what are known as complex traits. These traits are influenced not just by what alleles one has of one particular gene, but instead depend on which alleles one inherits at a number of different genes. Examples of complex traits include height, eye color, and hair color.
Many traits also do not depend solely on genetics, and the environment plays important roles as well. Height is a good example where genetics does play an important role in determining an individual's height but so do other factors such as nutrition during childhood. In these cases, we can only say that inheriting certain alleles affects the likelihood of developing a certain trait, but it does not completely control that trait (e.g. inheriting certain alleles of the BRCA1 and BRCA2 genes will increase the risk that an individual will develop breast cancer later in life, but not everyone with the alleles will develop breast cancer).
So, when you take a genetic test, scientists are looking at the particular variants present in your DNA. For most commercial DNA tests, these are mainly examining for variants that are commonly found in European populations. Finding rare variants requires either a specific test for that particular variant or sequencing the entire genome of the individual (which is more expensive and requires more expertise to interpret the results).
