The wavy fur of these cats , lacking the usual guard hairs of other breeds, gives them a strange, unsleek appearance which is exagerated by their slender, leggy bodies. Moreover the coat is very thin, therefore the Rex Cats would be at a disadvantage in many climates: they are not properly protected from both cold and heat. 
      There are now records of at least 17 different Rex Cats lines. Some have been taken seriously and developed as new breeds. Others vanished in a single generation:

1930 - Prussian Rex. Not developed.
1930s - Karakul Cat. Not developed.
1946 - German Rex.
1950 - Italian Rex. Not developed.
1950 - Cornish Rex.
1953 - Ohio Rex. Not developed.
1959 - Oregon Rex. Not developed.
1959 - California Rex.
1960 - Devon Rex.
1972 - Victoria Rex
1985 - Dutch Rex.
1987 - Selkirk Rex.
1988 - Rexed Maine Coon.
1991 - Urals Rex
1990s - Longhair Rex. Eastern European breeders are reported to have crossed Rex Cats with Persians to create a longhaired Rex.
1990s- Missouri Rex.
1994- Poodle Cat - a new breed of Rex with folded ears, created by crossing Devon Rex with Scottish Fold.
Further reading:
Rex Cats  by J. Anne Helgren