There are two major forms of PKD: Autosomal Dominant, or ADPKD, and Autosomal Recessive, or ARPKD. The Dominant kind is much more common, affecting 1 in every 500 people — that’s the kind I have, and the kind that runs in my manager’s family. My manager, Bill Brazell, knew for most of his life that he might have it, and when he was a freshman in college he asked a doctor to check him for it. When someone with ADPKD has children, each child has a 50-50 chance of inheriting PKD.

The Recessive form is serious much earlier — killing some of its heirs before they reach the age of one month — and much more rare, affecting just 1 child in 20,000. Because two recessive genes must come together to cause this disease, ARPKD parents usually have never heard of PKD, and have no idea that they carry its gene. If you can remember Punnett squares from high school biology, you’ll know that first, each parent needs to carry the recessive gene (quite rare in itself), and second, that each of those parents’ children will have just a one-in-four chance of combining those two recessive genes.

Julia and Julian Roberts, who live in Atlanta, have a son and a daughter named Gage and Quinn — and both of these cute kids have ARPKD. There’s also an eye disorder in the mix. A terrific lady, Julia chronicles her daily trials in a renal blog, telling readers what it’s like to look for — and find — adults willing to donate a kidney to save your kids’ lives. Check it out. — Kenny