Natural history of prenatally diagnosed 46,X,isodicentric Y.

OBJECTIVES

The karyotype 46,X,isodicentric Y has rarely been reported in the context of prenatal diagnosis. The literature is replete with descriptions of individuals with 46,X,isodicentric Y/45,X mosaicism, presenting with a spectrum of phenotypes. The postnatal phenotype is believed to depend on the extent of mosaicism in the gonads or other affected tissues. The purpose of this article is to delineate the natural history of this chromosomal abnormality when identified in the context of prenatal diagnosis.

METHODS

We identified a 45,X/46,X,idicY karyotype in the structurally normal male fetus of a woman presenting with an abnormal triple screen. Four other prenatally ascertained cases were found in our files as well as ten in the medical literature.

RESULTS

Of the 15 cases presented here, 11 (73%) were reported as phenotypically normal males, 1 was found to have an epididymal cyst, and 1 had normal male genitalia, but was also found to have a cardiovascular defect. One out of 15 (7%) was found to have female genitalia and was therefore confirmed to have Turner syndrome. In one case, the outcome was not reported.

CONCLUSION

An individual diagnosed prenatally with idic(Y) may in many cases be a normal male, similar to the outcome for prenatally diagnosed 45,X/46,XY.