Objective: A new method in prenatal diagnostics allows to demonstrate certain numeric chromosomal aneuploidies in amniotic cells within 24 h in contrast to conventional methods which take 1–3 weeks. Materials: The experience with this rapid fluorescence in situ hybridization (FISH) method is compared to standard karyotyping and its clinical relevance is described in a large clinical pilot study. FISH on uncultured amniocytes has been performed from 12 weeks of gestation to the third trimester using commercially available chromosome-specific DNA probes for chromosomes 13, 18, 21, X and Y. Results: FISH was performed successfully in 3,150 prenatal cases. All trisomies 13, 18 and 21 and all cases with gonosomal aberrations were detected by FISH analysis. Neither false-positive nor false-negative results were obtained using FISH. For all analyzable disorders the FISH results were in complete agreement with standard cytogenetics. Conclusions: In our experience, FISH is a valuable and reliable method for rapid diagnosis of numeric chromosomal aneuploidies.

Chromosome analysis in a newborn, the daughter of diabetic parents, who showed multiple dysmorphic signs and malformations revealed direct duplication of a long arm segment of chromosome 3(3q2100 leads to 3q2700). Both parents have normal karyotypes. Compilation of the phenotype stigmata with those of 7 other patients and 1 fetus with partial trisomy 3q confirmed that clinical recognition of this syndrome is possible. It is characterized by hypertrichosis, typical craniofacial dysmorphia, frequent organ malformations and skeletal anomalies, as well as a peculiar dermatoglyphic pattern. It is a severe genetic disturbance, leading to death in the first months of life in many cases and only symptomatic care is advised.

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We report our cytogenetic experience of 1554 early amniocenteses between weeks 11 and 14 of gestation, of which 44 per cent were performed prior to week 14. The mean culture time was 14.5 days. Karyotyping was successful in 99.7 per cent of cases. In 9.9 per cent of cases, there was pseudomosaicism with a high rate of loss of an X-chromosome and structural aberration of chromosome 1, which may be due to the Chang medium. The mosaic rate was 0.5 per cent. The overall aberration rate was 2.8 per cent. Our data confirm the reliability of early amniocentesis, which is a serious alternative to standard amniocentesis and chorionic villus sampling (CVS).