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During pregnancy, a percentage of the cell-free DNA circulating in the maternal blood is represented by the cell-free fetal DNA (cffDNA), constituting an accessible source for noninvasive prenatal genetic screening. The coexistence of the maternal DNA, the dominant fraction of cell-free DNA, together with the cffDNA component and the scarcity of the cffDNA itself make applying traditional methods of genetics and molecular biology impossible. Next-generation sequencing methods are widely used to study fetal aneuploidies. However, in monogenic disorders, there have been relatively few studies that analyzed single mutations. We present a method for the analysis of an extended group of gene variants associated with recessive and dominant autosomal disorders using next-generation sequencing. The proposed test should allow a complete analysis of common genetic disorders and pathogen-associated variants for diagnostic use. The analysis of cffDNA for single gene disorders may replace invasive prenatal diagnosis methods, associated with the risk of spontaneous abortion and psychological stress for patients. The proposed test should assess reproductive risk for both genetic family disorders and de novo occurrences of the disease. The application of this method to a case of beta-thalassemia is also discussed.

IntroductionNon-invasive prenatal testing (NIPT) using cell-free foetal DNA has been widely accepted in recent years for detecting common foetal chromosome aneuploidies, such as trisomies 13, 18 and 21, and sex chromosome aneuploidies. In this study, the practical clinical performance of our foetal DNA testing was evaluated for analysing all chromosome aberrations among 7113 pregnancies in Italy.MethodsThis study was a retrospective analysis of collected NIPT data from the Ion S5 next-generation sequencing platform obtained from Altamedica Medical Centre in Rome, Italy.ResultsIn this study, NIPT showed 100% sensitivity and 99.9% specificity for trisomies 13, 18 and 21. Out of the 7113 samples analysed, 74 cases (1%) were positive by NIPT testing; foetal karyotyping and follow-up results validated 2 trisomy 13 cases, 5 trisomy 18 cases, 58 trisomy 21 cases and 10 sex chromosome aneuploidy cases. There were no false-negative results.ConclusionIn our hands, NIPT had high sensitivity and specificity for common chromosomal aneuploidies such as trisomies 13, 18 and 21.

Objective Non invasive prenatal testing (NIPT) using cell-free fetal DNA (cffDNA) has been widely accepted in recent years to detect common fetal autosomal chromosome aneuploidies and sex chromosome aneuploidies (SCAs). In this study, the clinical performance of our fetal DNA testing was investigated by analyzing the sex chromosome aneuploidy aberrations among 9985 pregnancies. The study was a retrospective analysis of collected NIPT data from the Ion S5 next-generation sequencing (NGS) platform obtained from Altamedica Medical Centre of Rome. Results NIPT analysis of 9985 pregnancies revealed 31 cases with abnormal SCA results (0.31%). Among the 31 positive NIPT cases, 22 women agreed to undergo fetal karyotyping, whereas 9 refused further analyses. Of the 22 women verified by karyotyping analysis, 77.3% (17/22) were confirmed to be true positive SCAs, whereas 22.7% (5/22) were false positive. Among the true positive cases, 53.0% (9/17) were positive for monosomy X, 17.6% (3/17) were positive for 47, XXX aneuploidy, 23.5% (4/17) were positive for 47, XXY aneuploidy, and 5.9% (1/17) were positive for 47, XYY aneuploidy. In conclusion, the present results confirm that NIPT is a potential method for SCA screening, although this technology needs to be further investigated to improve the test performance.

Introduction deletion of long arm of chromosome 1(1q-) is a rare condition. Clinical features include Dwarfism, severe mental retardation, microcephaly and short neck delineating the "intermediate 1q deletion syndrome". Case report we report a new case of interstitial deletion of the long arm of chromosome 1, diagnosed in a 22+3 weeks gestation fetus in which cytogenetic analysis localized a loss of genetic materials of 18Mb in the 1q25.3-32.1. Fetal ultrasound showed neurodegenerative defects resembling Dandy-Walker's syndrome and bilateral clubfoot. Conclusions clinical characteristics of our case are markedly mild. This suggests that the type and the extension of the mutation obtained through cytogenetic studies, CGH array and ultrasound evaluation should be taken into account for prognostic evaluation and management of these patients.