Antenatal cytogenetic testing in Havana, Cuba

INTRODUCTION Antenatal cytogenetic testing was started in Havana in 1984, as a diagnostic option for fetal chromosome complement. The techniques applied are amniocyte culture, chorionic villus sampling, cordocentesis and fluorescence in situ hybridization in interphase cells. OBJECTIVE Describe the results of antenatal cytogenetic testing in the cytogenetic laboratory of the Cuba's National Medical Genetics Center in Havana, from 1984 through 2012. METHODS A retrospective descriptive study was carried out of the 22,928 pregnant women who had antenatal testing with conclusive results during the period 1984-2012. Information was obtained from laboratory databases for four antenatal diagnostic techniques. Variables studied were: antenatal diagnostic method, indications for genetic testing, type of chromosomal abnormality detected and couple's decision concerning pregnancy continuation if hereditary disease was diagnosed. Results were reported in absolute numbers and percentages. RESULTS Overall positivity was 2.8% (641 cases). Of the total, 20,565 samples were from amniocyte culture (558 positive cases, 2.7%); 1785 chorionic villus sampling (38 positive, 2.1%); 407 cord blood culture (28 positive, 6.9%); and 171 fluorescence in situ hybridization in interphase cells (17 positive, 9.9%). Advanced maternal age was the predominant indication for amniocyte culture and chorionic villus sampling. Positivity was higher for the two less frequently used methods, cordocentesis (6.9% positivity) and fluorescence in situ hybridization (9.9%). The predominant chromosomal abnormality was Down syndrome, with 45.4% of cases detected (291/641; 279 pure lines and 12 mosaic trisomies), followed by Edward syndrome with 12% (77/641, 71 pure lines and 6 mosaics) and Patau syndrome 4.7% (30/641, 27 pure lines and 3 mosaics). Sexual aneuploidy with pure lines affected 6.9% of cases (44/641) and with mosaicism 4.7% (30/641). Structural chromosomal abnormalities were detected in 22.5% of cases (144/641); of these, 70.8% (102/144) were balanced and 29.2% (42/144) unbalanced. In 78.6% of cases (504/641) with chromosomal abnormalities, whether mosaic or pure, the couple opted to terminate pregnancy. CONCLUSIONS Antenatal cytogenetic testing has helped reduce chromosomal abnormalities, mainly in Havana, and has provided reassurance of chromosomally normal children for couples at high genetic risk. The percentage of continuing pregnancies after a diagnosis of major chromosomal abnormality has been low, supporting evidence of broad population acceptance of abortion as an option when severe genetic abnormalities are present.