Thank you for your speedy and comprehensive response. I really appreciate it! I will definitely make contact with Mayo Clinic in London. The iron tablets are controlling his CG, but once he ceased taking them earlier this year, he relapsed with severe anaemia, so we are back on the supplements and they have just added a PPI twice a day as well. He has no obvious other symptoms other than lethargy, which impacts his ability to play sport, socialise etc. I am glad to find this resource/forum, as my doctor in Spain has very limited knowledge of the condition.