Clinical Analysis of Prenatal Cytogenetic Diagnoses: Four-year Experience at Asan Medical Center / 대한산부인과학회잡지

OBJECTIVE: To review and evaluate a total of 2,372 cases of prenatal cytogenetic diagnoses at Asan Medical Center from 1999 to 2002. METHODS: We reviewed the medical records of the patients in whom the procedure for prenatal cytogenetic diagnosis was performed. A total of 1780 cases of amniocentesis, 455 cases of cordocentesis, and 137 cases of chorionic villus sampling were analyzed. The cytogenetic results, indications for prenatal cytogenetic diagnoses, maternal ages, and the profiles of abnormal karyotypes were reviewed. We calculated the positive predictive value of each indication for abnormal fetal karyotypes and evaluated a factor that was the most sensitive marker for abnormal fetal karyotypes. RESULTS: Among the 2,372 cases of prenatal cytogenetic diagnoses, abnormal karyotypes were identified in a total of 158 cases (6.7%). The most frequent indication for prenatal cytogenetic diagnosis was abnormal maternal serum screening (33.9%), followed by ultrasonographic abnormality (22.9%) and old age (20.0%). No significant difference was found between mean maternal age with and without abnormal fetal karyotypes after excluding balanced rearrangements and polymorphisms (31.9 +/- 5.3 vs. 32.1 +/- 4.5 years). Among the 92 cases of abnormal fetal karyotypes after excluding balanced rearrangements and polymorphisms, the most frequent indication for prenatal cytogenetic diagnosis was ultrasonographic abnormality (58.7%), followed by abnormal maternal serum screening (10.9%). The positive predictive value of ultrasonographic abnormality for abnormal fetal karyotype was 9.9%. CONCLUSION: Among the several indications for prenatal cytogenetic diagnosis, ultrasonographic abnormality could be the most predictive marker for abnormal fetal karyotypes.

Two Cases of Prenatal Diagnosis of 22q11.2 Deletion Syndrome (DiGeorge Syndrome) / 대한산부인과학회잡지

Before the exact location of its chromosomal abnormality was identified, 22q11.2 deletion syndrome was described as many different names depending on its presenting clinical features. Patients with this syndrome have a wide range of findings such as cardiac anomaly, abnormal face, thymic hypoplasia, cleft palate, and hypocalcemia. Cardiac involvement is a prominent feature and most of the patients have a conotruncal heart defect. 22q11.2 deletion is the most common chromosomal cause of congenital heart defect after trisomy 21. Familial transmission accounts for about 8 per cent of cases and most of the cases develop sporadically. Even in cases where this syndrome is inherited, the parents' chromosomal abnormalities are often discovered only after the deletion is suspected in their children. We describe two prenatal cases in which this syndrome was suspected by ultrasonogram and confirmed by fluorescent in situ hybridization (FISH). In both cases, there was no known prior family history of cardiac abnormalities or chromosomal abnormality. In one case, autopsy following termination further confirmed the diagnosis. In the other case, the mother was also found to have 22q11.2 deletion.