These assays are Because of the fact that the androgen receptor is on the X chromosome, CAIS is an X-linked disorder. In most cases, a mutation in the coding region of the gene for the AR can be demonstrated, and extensive structure-function studies have been carried out. Similar to all steroid receptors, the AR is a ligand-dependent transcription factor. Mutations in the gene encoding AR may consist of complete absence, large deletions, or point mutations introducing premature stop codons that cause complete disruption of the protein sequence. Patients can be normal males or somewhat eunuchoid with gynecomastia.
Mullerian structures are absent.
In at least one third of cases, even the most thorough investigation fails to reveal the underlying cause. Because genital appearances in such cases are highly variable, a staging system is extremely useful . Having defined the Prader grade by inspection of the genitalia, the examiner looks for other clues to the diagnosis. Asymmetry of the labioscrotal folds is seen more often in cases of mixed gonadal dysgenesis and true hermaphroditism than in partial androgen insensitivity or testosterone biosynthetic defects.