Prenatal diagnosis of chromosomal abnormalities by cytogenetic analysis is time consuming, expensive, and requires highly qualified technicians. Rapid diagnosis of aneuploidies followed by reassurance for women with normal results can be performed by molecular analysis of uncultured foetal cells in less than 24 h. Today, all molecular techniques developed for a fast diagnosis of aneuploidies rely on the semiquantification of fluorescent PCR products from short tandem repeat (STR) polymorphic markers. Our objective was to test a chromosome quantification method based on the analysis of fluorescent PCR products derived from non-polymorphic target genes. An easy to set up co-amplification of portions of DSCR1 (Down Syndrome Critical Region 1), DCC (Deleted in Colorectal Carcinoma), and RB1 (Retinoblastoma 1) allowed the molecular detection of aneuploidies for chromosomes 21, 18 and 13 respectively. Quantitative analysis was performed in a blind prospective study of 400 amniotic fluids. Four samples (1%) could not be analysed by PCR probably because of a low concentration of foetal DNA. Follow up karyotype analysis was done on all samples and molecular results were in agreement with the cytogenetic data with no false -positive or false -negative results. Our gene based fluorescent PCR approach is an alternative molecular method for a rapid and reliable detection of aneuploidies which can be helpful for the clinical management of high-risk pregnancies.

Prenatal diagnosis of fetal trisomy 21 is usually performed by cytogenetic analysis. This requires lengthy laboratory procedures, high costs and is unsuitable for large-scale screening of pregnant women. Today, trisomy 21 can be rapidly diagnosed within 24 h by molecular analysis of uncultured fetal cells using the semi-quantification of fluorescent PCR products from short tandem repeat (STR) polymorphic markers. The aim of our study was to test a chromosome quantification method on the basis of the analysis of fluorescent PCR products derived from non-polymorphic target genes. Co-amplification of a portion of DSCR1 (Down syndrome Critical Region 1) and the reference gene, CFTR (cystic fibrosis transmembrane regulator) enabled molecular detection of trisomy 21. Our method was successfully tested on a total of 154 amniotic fluids in a blind prospective study. Calculation of the DSCR1/CFTR ratio allowed us to distinguish between 152 normal amniotic fluids (mean ratio 0.99) and 2 amniotic fluids presenting a trisomy 21 status (DSCR1/CFTR ratio of 1.53 and 1.61, respectively). The results obtained by conventional cytogenetic analysis and our quantitative PCR method were concordant in every case. Our gene-based fluorescent PCR approach represents an alternative molecular method for rapid and reliable detection of trisomy 21, which can be helpful in the prenatal diagnosis of women at high risk of fetal trisomy 21.

Epiphyseal punctate calcifications (or epiphyseal stippling) are rare nonspecific prenatal features resulting from abnormal calcium deposition in enchondral bone formation sites. This abnormality belongs to a clinically and genetically heterogeneous group named chondrodysplasia punctata (CDP). The various etiologies observed in CDP include inherited errors of metabolism and skeletal dysplasias, anomalies of vitamin K metabolism, maternal autoimmune disorder, rare but well-recognized syndromes, and chromosomal abnormalities (Irving et al., 2008).We report on the prenatal diagnosis of complete trisomy 9 in amniotic fluid sampled following the discovery of epiphyseal punctuations and multiple congenital anomalies on second trimester fetal ultrasound. The diverse etiologies associated with epiphyseal stippling as well as suggestions for prenatal work-up are discussed.Fetal ultrasound at 22 weeks' gestation in a 26year-old G1P0 woman revealed multiple anomalies including brachycephaly, cerebellar vermis agenesis, corpus callosum agenesis, cleft lip and palate, ear anomalies, clenched hands, right renal agenesis, sacral vertebral anomalies and epiphyseal stippling in the hips and knees (Figure 1a).The woman and her husband were unrelated. During the first trimester, nuchal translucency thickness was 1.3 mm for a crown-rump length of 51 mm. Maternal serum screening estimated the Down syndrome risk at 1 : 400. The prospective parents were counseled and adviced that prognosis was poor because of the combination of severe malformations discovered on fetal ultrasound. They requested termination of pregnancy, and labor was induced at 24 weeks' gestation.The parents gave their consent for postmortem examination. The male fetus presented with intrauterine growth retardation (biometric measurements were compatible with 20 weeks' gestation-weight: 572.9 g, length: 32 cm, and OFC: 21.5 cm). He had multiple anomalies including brachycephaly, blepharophimosis, medial cleft lip and palate, micrognathia, hypoglossia, low-set malformed ears, prominent nose, short neck, clenched hands and feet, hypoplastic nails, elbow dislocation and fixed flexion of the hips, imperforate anus, penoscrotal hypoplasia, right renal agenesis and ureteral duplication of the left kidney, linear insertion of the atrioventricular valves without defect, thymic hypoplasia, and adrenal hypoplasia.Skeletal radiographs revealed epiphyseal stippling of the superior and inferior epiphyses of the femora (Figure 1b) and a calcification in the right hypochondria suggestive of a liver calcification. In addition, dislocations of shoulder, ankle, and hip articulations as well as flexion deformities of the joints of the hands were observed. Thirteen rib pairs were also noted. Neuropathologic findings revealed agenesis of the corpus callosum and postero-inferior hypoplasia of the vermis. Sterol quantifications on amniotic fluid obtained during termination of pregnancy were normal. Amniotic fluid culture karyotype revealed trisomy 9 in all 34 metaphases examined. Interphase...