It looks like current evidence points to a link between blushing from alcohol and increased risk for esophageal cancer. Do you think it is important to have a genetic test for the gene responsible and make the general public aware the risk?

-A curious adult from Minnesota

January 4, 2011

I think it is definitely important that we make the public aware of this risk. But there probably doesn't need to be a genetic test. The people who blush when they drink alcohol know who they are.

What they might not know about is their higher risk for esophageal cancer. Or that there is no increased risk if they don't drink any alcohol.

The DNA difference that causes them to blush is only a problem when they drink. No alcohol means no increased risk of esophageal cancer.

The alcohol breakdown process is controlled by a few different genes. Some genes have the instructions for breaking alcohol down into acetaldehyde. Another set of genes controls turning acetaldehyde into acetic acid.

ALDH2 is one of the genes in charge of turning acetaldehyde into acetic acid. Some people have a small variation in that gene so that it barely works. Scientists call this version ALDH2*.

Hi. I am 25 yo female with bilateral colobomas and was wondering about what causes it and whether genetic tests are available. The outward appearance of my eyes is \"weird\" to most. I conceal the look by wearing special contact lenses which are

-A graduate student from Texas

August 5, 2004

From what I've read, colobomas can be passed down through the generations but not always. When a coloboma is referred to as congenital, it means that it was present at birth; it does not mean that it is necessarily genetic. While what they are is pretty well understood, where colobomas come from is not.

Does DNA account for only physical attributes of a human being, or can it also carry an emotional history from one generation to the next? I am wondering if the psychological damage of slavery for African Americans, for example, is carried forward

-A curious adult from Washington

August 3, 2004

My first inclination was to answer no but then I got to thinking...

The reason my gut reaction answer was no is because there was a big debate early on in genetics about traits and how they are passed on.

One school thought that things we do and things done to us can be passed on. The other school argued that it is all about selecting the most fit individuals in a population who then pass their traits on.

If a person has a total gender reassignment - (sex change) no matter how extreme the operation goes with hormone injections etc; on a DNA level, the sex of that person is absolute?

-A curious adult from Singapore

July 23, 2004

No amount of surgery, hormone injections or anything else will change someone's DNA from a man's to a woman's (or vice versa).

As you know, for humans, sex is determined by the presence of a Y chromosome -- humans with an X and a Y chromosome are male and those with two X chromosomes are female. No current (or probably future) technology can replace a chromosome in all of our trillions of cells.

What is a polymorphic micro-satellite? How can the PCR reaction help us determine if the gene is polymorphic or not?

-A curious adult from Malaysia

July 22, 2004

A micro-satellite* is a small sequence of DNA that is repeated many times. The size of the repeated sequence is usually between 1 and 4 base pairs. When the number of repeats varies between people, a micro-satellite is called polymorphic.

Micro-satellites are usually located in DNA outside of genes and are found in all sorts of plants and animals. They are useful in figuring out who the father of a child is or who committed a crime.

The DNA from a PCR reaction is then run on an agarose gel. In an agarose gel, smaller pieces of DNA run faster and so are more towards the bottom of the gel. From looking at the figure on the right, can you guess who has a copy of A and B and who has two copies of A? That's right, Bob has a copy of A and B meaning he is heterozygous for this allele. Terri has two copies of A and so is homozygous.

My husband was recently diagnosed with FH-Familial Hypercholesterolemia. I\'m concerned that the extremely high cholesterol levels will likely lead to chest pains, high blood pressure and a heart attack. Can you tell me more about FH?

-A curious adult from California

Familial Hypercholesterolemia or FH is a genetic disease where you get really high levels of the bad cholesterol, LDL. If left untreated, high levels of LDL can lead to early heart attack and stroke. (I couldn't find any evidence that high cholesterol leads to high blood pressure.)

I recently found out I was pregnant with baby#4. My first 2 children are normal, #3 was born with cystic hygroma, I am wondering if this is genetic and the possibilities of this reoccurring. Thanks.

-A curious adult from Oregon

July 20, 2004

Cystic hygromas aren't usually inherited so they aren't genetic in that sense. Most cases (60-80%) are caused by problems with chromosomes and not single genes. These chromosomal abnormalities are problems that happen during egg or sperm production and are generally random; not something that runs in families. As a mother gets older, these types of chromosomal problems increase (Down syndrome is the classic example). This may make having another baby with a cystic hygroma more likely.

I have read, \"Genetically speaking, nothing differentiates one race from another. All humans share the same set of genes. There is no African gene, no Caucasian gene, no Asian gene.\" However, I also understand that there are genetic markers such

-A curious adult from California

July 14, 2004

At the gene level, people are much more the same than they are different. In fact, individual humans vary between each other much less than do individuals of almost any other species. All of this argues that we came from a small group of common ancestors in the recent past.

I have heard a lot about Down syndrome and chromosome 21. I have also heard a lot about chromosome 21 and Alzheimer\'s. Is there any correlation between Alzheimer\'s and Down syndrome? Isn\'t chromosome 21 the chromosome that is duplicated when some

-A curious adult from Michigan

July 13, 2004

You are right, both Alzheimer's and Down syndrome have been linked to chromosome 21. As you probably know, chromosomes have lots of genes, many of which can cause disease when mutated. Chromosome 21, which has around 225 genes, is involved in many diseases.

Alzheimer's and Down syndrome are caused by different changes in chromosome 21. Down syndrome is caused when some or all of chromosome 21 is duplicated. The Alzheimer's link is to a single gene, APP, found on chromosome 21.