Current status of prenatal diagnosis in Cuba: causes of low prevalence of Down syndrome.

OBJECTIVES: To analyze trends in cytogenetic prenatal diagnosis in Cuba and to analyze possible causes leading to a low Down syndrome prevalence in a country where the triple test is not available. METHODS: An analysis of the Cuban program in prenatal cytogenetic diagnosis from 1984 to 2012 was conducted. Results are described, with particular emphasis on indications, abnormal results, types of invasive procedures, and terminations of pregnancy. RESULTS: Cytogenetic prenatal diagnostic analyses (n = 75,095) were conducted; maternal age was the indication for 77.9% of the amniocenteses and chorionic villus samplings. The detection rate of chromosomally abnormal pregnancies was 2.3% for maternal age and increased to 8-9% for other indications. When a chromosomal abnormality was identified, 88.5% terminated the pregnancy. In 2002, the live birth prevalence of Down syndrome was 8.4 per 10,000 live births, and in 2012, 7 per 10,000. CONCLUSION: Prenatal diagnosis in Cuba has contributed to a significant reduction in chromosomal aberrations. The impact increased because of the demographic trends of the population, the high index of terminations of pregnancy, and the establishment of a network of cytogenetic laboratories throughout Cuba.

Avoiding a second amniocentesis to corroborate prenatal diagnosis by using refrigerated samples.

OBJECTIVE: This study is aimed to probe the usefulness of refrigerated aliquots of amniotic fluid to be used for fluorescence in situ hybridization (FISH) in order to perform an accurate prenatal diagnosis avoiding the risk related to an additional amniocentesis procedure and the psychological stress to the pregnant woman and her family. METHODS: Non-cultured amniotic fluid (AF) samples were analyzed by FISH. Such samples were divided into two groups. The first one included fresh collected AF (FCAF, N = 30). The second one included refrigerated samples of AF (RSAF, N = 12) to corroborate uncertain chromosome aberration identification obtained by conventional methods. Sample refrigeration did not exceed 18 days. RESULTS: No differences were found between groups. In the RSAF group, three cases of chromosomal mosaicismo and seven cases of pseudomosaicism were corroborated. No alteration adjudicated to aberrant chromosomal line presence was found in born children according to genetic specialists' criteria. In the two remaining cases, applied procedure allowed elucidating fetal sex in one case and the origin of a marker chromosome in the other. CONCLUSIONS: Amniocytes obtained from RAFS are a useful biological material to be assayed by FISH, achieving an accurate prenatal diagnosis and avoiding an additional amniocentesis.