Objective: To investigate the mechanism of the formation of a tetragametic chimera with true hermaphroditism (46,XX/46,XY).
Design: Molecular biologic analyses.
Setting: Outpatient clinic and laboratories of a university hospital.
Subjects: A true hermaphrodite with 46,XX/46,XY and the parents. MAIN OUTCOME ANALYSIS: Restriction fragment length polymorphism (RFLP) of the pseudoautosomal region on sex chromosomes.
Results: Whereas a normal diploid individual showed two bands, the true hermaphrodite showed four bands in the RFLP analyses. Evaluation of the molecular weights of the bands revealed two of them to be of maternal origin and the other two to be of paternal origin.
Conclusion: The two cell lineages composing the true hermaphrodite are heterogeneous because those originated from the fertilization of two genetically different maternal haploid cells by two different spermatozoa.