A Molecular Method for Classifying the Genotypes Obtained in a Breeding Colony from Testicular Feminized (Tfm) Rats

Introduction

The complete form of androgen insensitivity is an inherited X-linked syndrome in which genetic males fail to undergo masculinization as a result of defective functioning of the androgen receptor (AR). Affected males retain the female phenotype, although abdominal testes produce normal-to-elevated testosterone levels for males [1]. The testes in these rats are small and not fully descended, and spermatogenesis is blocked at meiotic prophase. The molecular basis of androgen insensitivity was investigated in testicular feminized (Tfm) rat by Yarbrough et al. [2], who demonstrated that a single base mutation of the Ar gene causes androgen insensitivity.

These animals can be essential in the investigation of the effects of androgens on the immune system or in sexual dimorphism, for example. The method devised by Freeman et al. [3] has been applied in these studies. This method necessitates dissection of the reproductive tract at the conclusion of the experiment. Sometimes, this process reveals the presence of Tfm males (X ^Tfm /Y) misidentified as masculinized mosaic females (X ^Tfm /X).

As the crucial step in this kind of experiments is the correct classification of the four possible genotypes, we have developed a simple molecular procedure for classifying the genotypes from just 200 µl of peripheral blood.

References

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