USH2A and retinitis pigmentosa 1: Unexpectedly, in the comparison of the recorded mutations of USH2A in nonsyndromic RP to USH2 in the Human Gene Mutation Database (HGMD,http://www.hgmd.cf.ac.uk/ac/index.php), there was no obviously different distribution of these mutations between the two kinds of retinal diseases; the mutations are rather scattered, located in the whole protein.