My daughter has this skin. Literally, she is so pale you can see the blood vessels.
They have suspected our daughter of having it for years. They've done the blood screen twice (I think at 3 & 5, or 4 & 6, I forget exactly) but it was negative both times. However she has several symptoms: severe chronic constipation, slow growth, horrible dental enamel, poor appetite, anxiety (however she also has ASD) and probably more I'm not thinking of as she has many fluky things. Autoimmune issues run in the family and she has certain markers such as Raynaud's Syndrome and Livedo Reticularis. Anyways, about a week ago, she has started breaking out in a rash every night after supper. We have no idea what it is. She gets itchy, and it slowly fades on it's own (or Benadryl helps). It's been suggested it could be any number of things of course, but one has suggested liver issues (her bowel medication can be hard on the liver), obviously food allergies as a possibility, or an auto immune issue.
my son is asd and also breaks out in a random occurring rash. he's been tested for several things but it's never been pinned down. fortunately it clears up within a couple of hours on it's own but the doctor has us give him a small dose of antihistamine to help as well. he's pale as a ghost as well-but i chalk that up to a combination of taking after my maternal side of the family (pale redheads) and an aversion to doing ANYTHING that entails being outside (sunburns and bugs are 2 of his anxieties).