Genetic links in families

Human DNA comes in the form of 23 pairs of chromosomes. We get one set from our mom. The other from dad. Our children will get one set of their DNA from us. But before we package it into eggs or sperm, it gets mixed together. To see how this works, look at the picture below. First, we line up each pair of chromosomes. In the picture, we line up chromosome 18 (A). Then, we swap segments (B). This mixes the DNA we get from our parents. That way, we pass along information in our DNA from both our parents to our children (C). Each time we make an egg or sperm cell, we get a different mix. Unless we are an identical twin, we only have part of our DNA in common with our siblings. We also share part of our DNA in common with our grandparents. And cousins. The more distant the relative, the less DNA we have in common. But we still have some parts in common. In DNA biobanks, like BioVU, there are family members included. We use biobanks to study links between DNA and diseases. Sometimes, we need to study unrelated people. If we include related people, it makes it harder to find a true link. But we also use biobanks to learn about different groups of people. So we might want to keep everyone who has segments of their DNA in common. Whether they are related or not. Scientists at Vanderbilt University Medical Center have a way to find related people in biobanks. They will use BioVU to look for people who share DNA in common. The will use their formulas to figure out if people are related. They will share their data with others. This will help everyone who uses BioVU. They will also look for links between the segments of DNA and diseases. We know that groups of people have segments of DNA in common. In the picture above, the Mom and Dad chromosomes are two colors. But, some of the segments might be the same. They might look more like this: The green are segments they have in common. The top green segments might be something everyone in the same population has in common. Like eye shape and color. Or skin color. Or hair type. These are “in general.” Each of these will vary within populations. And there will be exceptions. The bottom green segments might be common to people from the same country. My parents are both British. So the bottom green might be common to all British people. We can use BioVU to check if any green segments link to risk for a disease. Within the green parts, there might be gene changes. It is the gene changes that put us at risk for a disease. Not everyone will have those gene changes. But they may be more common in some groups than others.