Your piggies will be absolutely fine and at no more risk of illness than any other pig.
When breeding roan to roan or dalmatian to dalmatian, there is approximately a 1:4 chance of ending up with one or more lethal babies. Sadly, due to potential complex issues, many do not survive for long after birth. However, those who do will have problems to deal with, like being deaf/blind and having potential neurological conditions, but they really are a joy to have and enjoy life to the full! They are always white, with pink eyes (if they have them), but not all pink eyed white pigs are lethal. A roan pig is a pig with any white hair, along with another colour - so you can see how much of a risky business it is.
The Excellent Adventure Sanctuary is home to ten lethal pigs, all of whom have come to us to be close to specialist veterinary care, should it be needed. Below is a picture of the legend that is Captain Darling - as you can see, he has no fully formed eyes and he is deaf/blind. He lives with his brother Igor, who is a normal pig, and a friend Patch. The Captain rules the roost in every way!
Under the Sanctuary's care, we currently have lethal piggies Captain Darling, Sidney, Henry, Stanley, Basil, Albert, Snowdrop, Snowflake, Florence and Mabel. We have had five others - Bill, Ted, Edith, Walter and Tweedledee, who have now all passed away.
You can read more here:
Cavy Angel's Guinea Pig Rescue