A survey of the list of human proteins associated with diseases provided by Uniprot (http://www.uniprot.org/docs/humpvar release 8_2_2011) provides a flavour of the peculiarity of AGAL_HUMAN and reveals that, excluding tumour suppressors, this protein has the fifth highest ratio between reported missense mutations and chain length; only chain A and B of haemoglobin, Gap junction beta-1 protein (associated with Charcot-Marie-Tooth disease), Transthyretin (associated with amyloidosis type 1) and Phenylalanine-4-hydroxylase (associated with phenylketonuria) have higher rates. Here, PAH is linked to phenylketonuria.