Martin and Bell in 1943 described a large pedigree without knowledge of the cytogenetic anomaly and without considering the microorchidism. Sutherland in 1977 described a method for a secure and constant «Darstellung» of the fragile point.
Renpenning's syndrome differs from Martin-Bell in the absence of any fragile site on the X-chromosome. Renpenning’s cases (short stature, moderate microcephaly, neurological disorders) were reported in a Dutch Mennonite pedigree from Alberta and Saskatchewan. Escalante's syndrome is the fragile X type. This term has been used in Brazil and other South American countries.