I am on page 4... hope to read the rest because I fall asleep. :-)

Ever since I read that identical twins can differ greatly in terms of epigenetics (e.g., gene copy number), I thought this could account for why the concordance between monozygotic twins was not 100% with AIS even if there are separate genes coding for incidence, progression, and severity. Epigenetics might be a possible answer but this research is in its infancy.