Article Text

  1. M. J.H. Willis,
  2. L. M. Bird,
  3. J. T. Mascarello,
  4. M. Dell'Aquilla,
  5. M. C. Jones
  1. University of California, San Diego and the Children's Hospital


The karyotype 46,X,isodicentric Y has rarely been reported in the context of prenatal diagnosis. The literature, however, is replete with descriptions of individuals who are 46,X isodicentric Y/45,X, presenting with a spectrum of phenotypes from Turner syndrome, to ambiguous genitalia, to hypospadias or cryptorchidism, to adult males with normal genitalia, infertility and azoospermia. There are also a few case reports of structurally normal male patients who were found to have idic(Y) as part of a workup for mental retardation. The postnatal phenotype of a given individual is believed to depend on the extent of mosaisim in the gonads, and possibly in any affected tissue. We recently identified prenatally 45,X/46,X,idicY in the structurally normal male fetus of a woman presenting for prenatal testing for advanced maternal age. Three other prenatally ascertained cases were found in our files as well as three in the literature. The purpose of this paper is to delineate the natural history of this chromosomal abnormality when identified in the context of prenatal diagnosis. Case 1 has completely normal physical findings on level 2 prenatal ultrasound. Case 2 is a boy now 5 years old with mild short stature. Case 3 is a phenotypically normal male infant who had no medical problems at last contact. Case 4, a phenotypic female on prenatal ultrasound, was lost to follow up. The 3 literature cases of idic(Y) found in prenatal diagnosis where karyotype was performed for reasons other than abnormalities on prenatal ultrasound were all reported to be normal males. Although this is a small series, the outcome for an individual diagnosed prenatally with idic(Y) may in many cases be a phenotypically normal male, similar to the outcome for prenatally diagnosed 45,X/46,XY. The period of follow up is not long enough, however, to make any statements about fertility.

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