It is not on the rise. Collodian babies usually survive and have for the last 20-30 years or more. The rise of the internet means we are more aware of other affected families, but the birth rate of 1 in 250,000 has been pretty constant throughout any of the literature dating back to the 1970s.
Genetic testing is useful if you wish to be involved in research studies where they need people affected with a specific mutation, and for having future children, either amniocentesis testing after you're pregnant, or IVF/PGD treatment prior to becoming pregnant. Other than that, it doesn't really do anything for you.
With LI, there's a 50% chance that the unaffected kids are carriers, but then they have to marry the 1 in 500 people that are also carriers before it will show up again in descendants. That can take 4-5 generations.
For the affected kids, all the children are carriers, but would only have the disorder if the affected person married a carrier, and then half would be carriers with normal skin and the other half would have LI.
Ichthyosis-en-Confetti Type 2
Husband, Nathan - 10, Elliot - 7, Oliver - 4, all affected.
I also have an unaffected daughter, age 8.
email: jennifer at confettiskin dot com
facebook - find me on "ichthyosis mommy spot" or "friends of ichthyosis"