Editor's Note: The following is quoted verbatim, without permission, from one of the last hardback versions (7th edition, Johns Hopkins University Press, Baltimore, 1986, pages xxiii-xxv) of Victor A. McKusick's immortal classic Mendelian Inheritance in Man. Short of downloading the complete text of about 15 Mbytes, I was unable to find this material in Online Mendelian Inheritance in Man.
Terminology
The terminology related to many genetic disorders presents difficulties, especially when the basic defect is unknown. The naming of syndromes is a rather helter-skelter, hit-or-miss process. Like all language, the names of syndromes evolve; preferences are a matter of usage. Although personal bias has inevitably played a role in the choice of terms used here, I have atttempted to use most generally encountered terms in entry titles and to cross-index synonyms.
Optimally, the name for a genetic trait or disorder should have some relation to the basic defect, but, as I have said, this is often, indeed usually, impossible because of ignorance of the nature of the trait. The name should be imaginative, in the sense that it should conjure up an image of the phenotype; that is, it should be mnemonic. It should be euphonious. It should also be appropriate for transmittal to patients. Tongue-twisters and possibly embarrassing terms such as as 'gargoylism' are not acceptable. Some 7 methods of naming are in use:
1. Eponyms are, improperly I think, maligned in some quarters. Admittedly, they should be used sparingly because they put a strain on the memory. Many, such as Alzheimer, Ehlers-Danlos, Ellis-van Creveld, Huntington, Marfan, Menkes, Pelizaeus-Merzbacher, and Wilson, are too well established to be avoided, and in addition, no entirely satisfactory noneponymic designation is available.
The virtue of eponyms is that they convey no preconceived notions as to the nature of the abnormality. The Hurler syndrome was, time showed (McKusick, 1972), a better designation than lipochondrodystrophy, which was used the Index Medicus- long after the fundamental fault was known to concern mucopolysaccharide, not lipid. Most eponyms are physicians' names, but not all; witness Hartnup (23450), Byler (21160), and Christmas (30690) diseases, which were named for patients.
As a rule, the possessive form of eponyms has not been used; for example, the Marfan syndrome, not Marfan's syndrome, will be found in the catalogs. The reason is the eponym is merely a 'handle'; often the man whose name is used was not the first to describe the condition (the word America- is a classic example of naming for someone other than the first discoverer) or did not describe the full syndrome as it has subsequently become known. As Darwin put it, 'Credit is rarely given to the one first to make a discovery but rather to him which convinces the public.' The nonpossessive form of eponyms was recommeneded by Current Medical Information and Terminology , beginning with the fourth edition (1971).
The following are suggested rules concerting use of the possessive form of eponyms:
A. Do not use the possessive form of an eponym
i. with a word beginning with a sibilant ('c,' 's,' or 'z,')--e.g., syndrome (Marfan syndrome), sign (Chvostek sign), zone (Looser zone), Laennec cirrhosis, Erdheim cystic medial necrosis;
ii. with a compound eponym (whether hyphenated or not)--e.g., the Ellis-van Creveld syndrome, the Pierre Robin syndrome;
iii. with an eponym that ends in 'ce,' 's,' or 'z,'--e.g., Bayes, Jeghers, Lenz, Nance, Spatz, Williams.
B. When the nonpossessive form of an eponym is used, adding 'the' before it--e.g.the Marfan syndrome, the Hunter syndrome--is recommended.
C. Consider use of the possessive form optional in situations other than those listed under (A) as interdicting it. Although a consistent practice (e.g., exclusive use of the nonpossessive) has much to recommend it, some nonpossessive terms, because of long usage of the possessive, roll off the tongue awkwardly--e.g., the Huntington disease, the Wilson disease, the Hodgkin disease, etc.
3. Another method is to pick out one striking feature for use as the name of the condition--i.e., to name the whole for a part thereof (e.g., the whistling face syndrome [19370]). 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.
4. A fourth method of naming involves the construction of acronyms, such as TAR syndrome (27400) and VATER association (19235), or the combination of the initials of features, as in EMG syndrome (22560) and ORD syndrome (31120, 25210). These systems have mnemonic usefulness. Robert J. Gorlin, in particular, has been a proponent and user of this system, which has the disadvantage that more than 1 entity may qualify--e.g., as an oral-facial-digital (OFD) syndrome
5. Geographic names for genetic disorders include familial Mediterranean fever (24910) and the Indiana (10940) and Portuguese (10480) varieties of amyloidosis. The Amsterdam type of malformation syndrome is now more commonly known as the Cornelia de Lange syndrome (21790). Thalassemia is essentially a geographic term. Geographic terms are inevitably ethnic as well--e.g., the African type of G6PD deficiency. Geographic or institutional (e.g., hospital) names have been used extensively for hemoglobin types.6. 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. Numbers are also used to differentiate the oral-facial-digital syndromes--OFD I (31120) and OFD II (25210).
7. In some cases the nature of the basic defect is used in the name, especially when it lends itself to easy typography and speaking. G6PD deficiency (glucose-6-phosphate dehydrogenase deficiency) is a successful example. Factor VIII deficiency is a synonym for hemophilia A. HGPRT deficiency is a reasonably easy synonym for the Lesch-Nyhan syndrome.
There is little rhyme or reason to the use of disorder, disease, syndrome , and anomaly. Disease- often has unhappy connotations to the layman; disorder- or syndrome- is more satisfactory. Some suggest that a syndrome be called a disease when the basic defect becomes known. Association- and anomalad- are terms that have been proposed for some birth defects (Smith, 1974), but are not likely to be useful in connection with mendelian phenotypes.[...and much, much more....]