Okay, two days later and I'm not feeling quite so freaked out.
1. Lovergirl suggested that one reason why there is a high correlation with abnormalities is that people don't usually go to a specialist for a mere birthmark. So maybe it is only the babies with more severe abnormalities go to the specialists and then they notice this correlation with CMTC. Maybe there are all these people running around, perfectly normal, with CMTC, who have just never thought to go and have it identified. Particularly as it fades after two years.
2. As Anon (Suse?) pointed out, a lot of the associated abnormalities are also present at birth, so if Lucky hasn't got them now, she's not going to.
3. Actually a lot of the abnormalities lumped in the 50% figure are fairly mild - like a portwine birthmark (and Lucky does have that, so hopefully that's used up her quota of associated abnormalities) - and others, like glaucoma, are manageable if you catch them early. We have to go to the opthalmologist every six months during her childhood, apparently.
4. As my sister pointed out, while some instances cited on the net of atrophy or hypertrophy of a limb is extreme, for most of the people with this symptom it amounts to a difference of 1 or 2 cm difference in diameter between the limbs. I think that's the one I've been worrying about the most, imagining Lucky as a teenager with a tiny little arm that hasn't grown since she was a baby.
5. Some of the people on the net with CMTC have it all over their bodies. Lucky only has it on one arm, and just the forearm.
5. And finally, if she
should happen to have problems, she surely couldn't do much better than having a psychologist and an occupational therapist for parents.
I really
really valued getting all your messages of support. It's times like this that you really like to know someone is noticing your little life, isn't it?