Epidemiology of PKD

Polycystic Kidney Disease can affect anyone – it is not particular to men or women, or any specific ethnicity, meaning we are all at equal risk for inheriting the disease. There are currently around 600,000 people in the United States living with PKD, making it the fourth leading cause of kidney failure. Kidney failure is irreversible – the kidneys are essential!

There isn’t much you can do to prevent yourself from acquiring this disease. It is a genetic disease, meaning it is passed from parent to child, just the same as eye color or hair color. Knowing whether or not your parents have it is the best information you have regarding your chances of developing kidney failure related to cysts.

Genes are the things that carry the hair or eye color message from parent to child, and each child receives one gene from each parent for the same thing. Some genes are stronger than others, and they are always in charge. These are called dominant genes. The weaker genes are called recessive genes. We can physically see dominant genes in people more often, because the dominant gene is “covering up” the recessive gene. So if you had a set of parents, one with brown hair and one with red hair, their child almost always has brown hair. This is because the gene for brown hair is dominant, and covers up the gene for red hair.

Polycystic Kidney Disease comes in two forms, both recessive and dominant. Because dominant is more commonly passed on, this version of the disease is more commonly seen. It is very difficult for someone to acquire a recessive genetic disease! Let’s go ahead and see how that works.

Sticking with the hair and eye color examples – each child receives one gene for hair color from each of their parents. Since the parents were children once too, they also received two genes for hair color, one from each parent. So when a child is born, they have 4 genes – two from each parent – that they could potentially receive. It is random which one they will get from each parent.

Great visual example of how this works - the black abnormal gene represents the dominant PKD gene. So, as you can see, anyone with Polycystic Kidney Disease has a 50% chance of passing on the disease to their children. And - we know that PKD doesn't usually become symptomatic until the individual is at least in their 30s, if not later in life, at which point they have likely already had children if they are going to do so. This presents a heavy decision for families with known history of PKD, and that is something we can get into later.

Citations:

Polycystic Kidney Disease (2014). Retrieved January 14, 2015 from https://www.kidney.org/atoz/content/polycystic

Dominant Inheritance (2014). Retrieved January 14, 2015 from http://www.ebnurse.org/index.php?id=27