Brief historical note: the concept of "gonadal dysgenesis".

The history of gonadal by dysgenesis cautions against overinterpretation of data: The streak gonads are neither the result of dysgenesis nor of embryonic origin but represent late fetal/neonatal degeneration; the X-chromatin-negative character of the buccal smear and the frequency of color vision defects did not indicate male sex in the Ullrich-Turner syndrome but rather an XO constitution; severity of dysgenesis did not correlate with risk of gonadal neoplasia but with genotype; the gonadal lesion in the Ullrich-Turner syndrome was not due to a pituitary defect but a primary ovarian lesion; patients with the Noonan syndrome do not have the Turner phenotype. The concept of gonadal dysgenesis, introduced to Kermauner in 1912, has outlived its usefulness. Improved methods of phenotype analysis, family studies, and endocrine and cytogenetic methods have showen it to be causally and pathogenetically heterogeneous and have contributed to a better identification and delineation of the several different genetic entities which it formerly comprised.