Healthy female carriers of a gene for the Alport syndrome: importance for genetic counseling.

Of 305 female obligatory carriers of a gene for the Alport syndrome identified in the literature, 37 (12.1%) had no clinical or laboratory signs or symptoms (renal, audiometric, ophthalmological) of disease. The prevalence of unaffected female obligatory carriers appeared not to vary according to age or to the severity of the illness in male members of any pedigree. Normal clinical or laboratory data for any female liable for the Alport syndrome must thus be interpreted with caution.