This report describes an unusual case of monozygotic female twins, one phenotypically normal and one with ovarian dysgenesis and other congenital anomalies. The twins were born by cesarean section at 29 weeks of gestation, with birth weights and lengths at the fifth percentile for gestational age. They were diamniotic but monochorionic; monozygosity was confirmed by molecular fingerprinting. At birth, twin A had a single umbilical artery and a displaced and dysplastic left thumb. She also had a patent ductus, an atrial septal defect, and ventricular septal defect, which required surgical correction. Elevated serum gonadotropins in twin A suggested ovarian dysfunction. Laparoscopy revealed no ovary on the left and a streak gonad on the right. A biopsy showed fibrovascular connective tissue but no epithelial cells or follicles. At age 12, when twin B entered puberty, estrogen replacement therapy was initiated in twin A with estradiol (E2) 20 ng/kg orally. This dose was increased gradually over several years, guided by clinical, vaginal cytologic, and hormonal findings, using twin B as the model. Growth and development proceeded appropriately. Twin A reached an adult height of 156.4 cm, close to twin B's height of 159.7 cm.
Ovarian dysgenesis, in most instances, is associated with X-chromosomal anomalies. In our case, several karyotype analyses on lymphocytes from both twins, as well as a fibroblast culture from a biopsy in twin A, showed a normal 46, XX constitution. Fluorescence in situ hybridization performed on lymphocytes from both twins using X- and Y-centromeric probes showed no sex chromosome mosaicism or Y-chromosome material.
*Postdoctoral Fellow; †Professor and Chief Division of Genetics, Department of Obstetrics and Gynecology, Georgetown University Hospital, Washington, DC; and ‡Clinical Assistant Professor; §Professor Emeritus, Department of Pediatrics, Georgetown University Medical Center, Washington, DC.
The authors have disclosed that they have no significant relationships with or financial interests in any commercial company that pertains to this educational activity.
Lippincott Continuing Medical Education Institute, Inc. has identified and resolved all faculty conflicts of interest regarding this educational activity.
Reprints: Malcolm M. Martin, MD, Department of Pediatrics, Georgetown University Medical Center, Kober-Cogan Building, Room 305-6, Washington, DC 20007. E-mail: martinm3md@GTCinternet.com.
Chief Editor's Note: This article is the 23rd of 36 that will be published in 2007 for which a total of up to 36 AMA PRA Category 1 Credits™ can be earned. Instructions for how credits can be earned precede the CME Examination at the back of this issue.