John M. Opitz has been the main proponent of this system. Arachnodactyly was an early synonym for the Marfan syndrome, but proved to be an unsatisfactory one because spider-fingers is not an impressive feature of some bona fide cases and, in addition, occurs in other conditions. These systems have mnemonic usefulness. Thalassemia is essentially a geographic term. A numbering system has been used in connection with the glycogenoses, the hyperlipoproteinemias, the mucopolysaccharidoses, the Ehlers-Danlos syndromes, and other categories of genetic disorders and has had considerable usefulness, particularly perhaps with the mucopolysaccharides.
Problems arise when different workers use different numbers.
In some cases the nature of the basic defect is used in the name, especially when it lends itself to easy typography and speaking. There is little rhyme or reason to the use of disorder, disease, syndrome , and anomaly. Some suggest that a syndrome be called a disease when the basic defect becomes known.