The molecular revolution has produced its own nomenclature. Some say that we should adopt molecular nomenclature to replace syndrome nomenclature; others maintain that we should keep syndrome nomenclature to keep learning hurdles to a minimum. Here, we adopt an integrated approach suggested by Biesecker [1998]. We think that molecular nomenclature should be taken into account for three reasons. First, in some instances the same mutation may cause two different syndromes. Second, different mutations may sometimes cause the same syndrome. Third, there may be phenotypic/molecular correlations [Cohen and Mac-Lean, 1999].
There are many different mutations causing Crouzon syndrome and Pfeiffer syndrome on fibroblast growth factor receptor 2 (FGFR2). Some of these mutations may cause both Crouzon syndrome and Pfeiffer syndrome, for example, Cys278Phe [Cohen, 1997[Cohen, , 1999]]. One way to integrate phenotypic and molecular diagnoses would be to indicate the phenotype when the mutation is the same:
Crouzon syndrome, FGFR2, Cys278Phe Pfeiffer syndrome, FGFR2, Cys278Phe Second, Pfeiffer syndrome may be caused by one mutation on FGFR1 and by many mutations on FGFR2 [Cohen, 1997[Cohen, , 1999]]:
Pfeiffer syndrome, FGFR1, Pro252Arg Pfeiffer syndrome, FGFR2, Thr341Pro If a syndrome is rare, then OMIM numbers could be used as well. This does not apply to Crouzon and Pfeiffer syndromes because they are not rare, but OMIM numbers are used to be consistent with this example:
Crouzon syndrome (123500), FGFR2, Cys278Phe Pfeiffer syndrome (101600), FGFR2, Cys278Phe A third example shows how phenotypic/molecular correlations apply to Apert syndrome, which has two common causative mutations in two adjacent amino acids on FGFR2 [Slaney et al., 1996]: