Performance analysis of non-invasive prenatal testing for trisomy 13, 18, and 21: A large-scale retrospective study (2018-2021).

Background: Non-invasive prenatal tests (NIPT) are used to screen for trisomy 21, 18, and 13. This study investigated NIPT performance and the clinical significance of its results. Methods: Pregnant women (n = 282,911) participating in a free NIPT (April 2018-December 2021) were screened for common trisomies, and the results were retrospectively analyzed. NIPT performance was evaluated by its positive predictive value (PPV), sensitivity, and specificity. Results were analyzed using number, percentage, and chi-squared/t-test analyses. Results: After NIPT screening, patients with common trisomies (n = 746) included 457 with T21, 160 with T18, and 129 with T13. Seven false negative cases were identified. High PPV (86.81 %, 56.81 %, 18.18 %), sensitivity (99.25 %, 98.33 %, 100.00 %), and specificity (99.98 %, 99.98 %, 99.97 %) values were detected for trisomy 21, 18, and 13, respectively. The PPVs of common trisomies were significantly different between pregnant women older than 35 (85.53 %, 136/159) and those aged 35 or younger (58.90 %, 311/528) (χ2 = 125.02, P = 2.20e-16). As the NIPT uptake increased from 2018 to 2021, live-born birth defect incidence decreased. Conclusion: NIPT performed well in screening for T21, T18, and T13. Our discoveries offer an important and useful guideline in laboratory and clinical genetic counseling.

Retrospective analysis of the risk factors associated with failure in obtaining effective noninvasive prenatal test results and pregnancy outcomes: a case-control study.

OBJECTIVE: To explore the pregnancy outcomes of women who couldn't obtain effective results from noninvasive prenatal testing (NIPT) and examine the factors leading to test failure. METHODS: From April 2017 to December 2019, 120,041 pregnant women enrolled for voluntary NIPT. The case group comprised of 274 (274/120,041) women who failed to obtain effective NIPT results, and the control group (n = 540) was from the same population who obtained effective NIPT results and matched by age at a 1:2 ratio. Abnormal pregnancy rates between the two groups were analyzed using Chi-square analysis. NIPT failure risk factors were analyzed using logistic regression analysis. RESULTS: Logistic regression analysis showed that increased maternal age (OR = 0.988; 95% CI = 0.982-0.994), increased pregnancy age (OR = 0.989; 95%CI = 0.988-0.991), and decreased cell-free fetal DNA concentration (OR = 1.050; 95%CI = 1.043-1.058) were independent risk factors for NIPT failure. Fifteen cases showed fetus loss in cases of NIPT failure. There was a significant difference in abnormal pregnancy rate between the NIPT success and failure groups (χ2 = 50.943, P < 0.05). EXPERT COMMENTARY: The specific interventions, guidance, and precautions are needed for pregnant women who have no effective NIPT results.

Cell-Free DNA Screening for Sex Chromosome Abnormalities and Pregnancy Outcomes, 2018-2020: A Retrospective Analysis.

To evaluate the efficacy of non-invasive prenatal screening (NIPT) for detecting fetal sex chromosome abnormalities, a total of 639 women carrying sex chromosome abnormalities were selected from 222,107 pregnant women who participated in free NIPT from April 2018 to December 2020. The clinical data, prenatal diagnosis results, and follow-up pregnancy outcomes of participants were collected. The positive predictive value (PPV) was used to analyze the performance of NIPT. Around 235 cases were confirmed with sex chromosome abnormalities, including 229 cases with sex chromosome aneuploidy (45, X (n = 37), 47, XXX (n = 37), 47, XXY (n = 110), 47, XYY (n = 42)) and 6 cases with structural abnormalities. The total incidence rate was 0.11% (235/222,107). The PPV of NIPT was 45.37% (235/518). NIPT accuracy for detecting sex chromosome polysomes was higher than that for sex chromosome monomers. The termination of pregnancy rate for fetal diagnosis of 45, X, and 47, XXY was higher than that of 47, XXX, and 47, XYY. The detection rate of fetal sex chromosome abnormalities was higher in 2018-2020 than in 2010-2012 (χ2 = 69.708, P < 2.2 × 10-16), indicating that NIPT is greatly efficient to detect fetal sex chromosome abnormalities.

Prenatal diagnosis of complete paternal uniparental isodisomy for chromosome 3: a case report.

BACKGROUND: Uniparental disomy (UPD) is defined as an inheritance of two chromosomes from only one of the parents with no representative copy from the other. Paternal-origin UPD of chromosome 3 is a very rare condition, with only five cases of paternal UPD(3) reported. CASE PRESENTATION: Here, we report a prenatal case that is only the second confirmed paternal UPD(3) reported with no apparent disease phenotype. The fetus had a normal karyotype and normal ultrasound features throughout gestation. Copy neutral regions of homozygosity on chromosome 3 were identified by single nucleotide polymorphism (SNP) array. Subsequent SNP array data of parent-child trios showed that the fetus carried complete paternal uniparental isodisomy (isoUPD) of chromosome 3. The parents decided to continue with the pregnancy after genetic counseling, and the neonate had normal physical findings at birth and showed normal development after 1.5 years. CONCLUSIONS: These findings provided further evidence to confirm that there were no important imprinted genes on paternal chromosome 3 that caused serious diseases and a reference for the prenatal diagnosis and genetic counseling of UPD(3) in the future.

Prevalence and spectrum of thalassaemia in Changsha, Hunan province, China: discussion of an innovative screening strategy.

Hunan province located in the south of China has a high incidence of haemoglobinopathies. In the present study, we surveyed the accurate population frequency data of the local population in Changsha city of Hunan province in China. The data includes the carrying rate, gene mutation types and their distribution features for thalassaemia. In total, 7500 consecutive samples from five geographical areas of Changsha were analysed for both haematological and molecular parameters. Therewas a high prevalence of carriers of α-thalassaemia (2.57%), ß-thalassaemia (1.9%) and both α-thalassaemia and ß-thalassaemia (0.08%). Overall, 4.54% of the population in this area represented heterozygous carriers of α-thalassaemia and ß-thalassaemia. The mutation spectrum of α-thalassaemia and ß-thalassaemia and its haematological characterization were fully described for this area. The present study is the first to report the prevalence of thalassaemia in Hunan province population. Both α-thalassaemia and ß-thalassaemia carriers are widely distributed in Changsha. The knowledge gained from the present study will allow for an estimation of the projected number of pregnant women at risk for thalassaemia, and the design of a screening strategy for the control of thalassaemia in Changsha.