Hi, Sisa! It sounds like you've had an ordeal with getting your son to a healthy place. Glad to meet you!
I don't know of any types of ichthyosis that cause dilated kidneys or bloody stool or heart murmurs directly. There are a few types that are very rare and syndromic with different problems, but generally the skin is a much more significant part of the problem.
Prematurity isn't specifically associated with ichthyosis, but there are an awful lot of reports of preterm affected kids, even my own.
As for the skin itself, I'm going to take a stab at it. If it is ichthyosis (and it might be something else), I'd do some research into X-linked. It passes down the mother's side of the family, invisible in the girls and pops up in roughly half the boys of mother's female relatives. If your mom only has brothers, none of their kids would be affected, but some of the brothers might be. If she has sisters, you might have a couple affected cousins. It's caused by a gene called steroid sulfatase and is a pretty easy one to do genetic testing - just a blood draw. It can cause labor to stall during pregnancy, and is often mistaken for Down Syndrome when they do the Triple Screen test in early pregnancy.
For scale management, have you tried out any of the acid lotions, like Lac Hydrin (12% ammonium lactate) or glycolic acid or urea lotions? They tend to work really well on both IV and x-linked varieties to loosen the scale. Follow it up with whatever regular cream you've been using. I know a lot of the UK folks use Oilatum in the bath and I've heard good things about it.
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"