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The increased life expectancy of individuals with Down syndrome (DS) is associated with increased prevalence of trisomy 21-linked early-onset Alzheimer's disease (EOAD) and dementia. The aims of this study of 14 brain regions including the entorhinal cortex, hippocampus, basal ganglia, and cerebellum in 33 adults with DS 26-72 years of age were to identify the magnitude of brain region-specific developmental neuronal deficits contributing to intellectual deficits, to apply this baseline to identification of the topography and magnitude of neurodegeneration and neuronal and volume losses caused by EOAD, and to establish age-based staging of the pattern of genetically driven neuropathology in DS. Both DS subject age and stage of dementia, themselves very strongly correlated, were strong predictors of an AD-associated decrease of the number of neurons, considered a major contributor to dementia. The DS cohort was subclassified by age as pre-AD stage, with 26-41-year-old subjects with a full spectrum of developmental deficit but with very limited incipient AD pathology, and 43-49, 51-59, and 61-72-year-old groups with predominant prevalence of mild, moderately severe, and severe dementia respectively. This multiregional study revealed a 28.1% developmental neuronal deficit in DS subjects 26-41 years of age and 11.9% AD-associated neuronal loss in DS subjects 43-49 years of age; a 28.0% maximum neuronal loss at 51-59 years of age; and a 11.0% minimum neuronal loss at 61-72 years of age. A total developmental neuronal deficit of 40.8 million neurons and AD-associated neuronal loss of 41.6 million neurons reflect a comparable magnitude of developmental neuronal deficit contributing to intellectual deficits, and AD-associated neuronal loss contributing to dementia. This highly predictable pattern of pathology indicates that successful treatment of DS subjects in the fourth decade of life may prevent AD pathology and functional decline., (© 2021. The Author(s).)

Objective: To investigate the clinical efficiency of noninvasive prenatal test (NIPT) identifying fetal chromosomal aneuploidies., Materials and Methods: In the present study, 917 women with high-risk pregnancies were invited to participate in an NIPT trial based on an Illumina HiSeq massively parallel sequencing platform. Abnormal cases in NIPT were validated by karyotyping and fluorescence in situ hybridization (FISH) analysis. All of the participants' infants were examined clinically and followed up for at least 6 months., Results: A total of 35 (3.82%) high-risk pregnancies were detected with abnormal results in NIPT, which included 25 cases (2.73%) of trisomy 21 (Tri21), four cases (0.44%) of trisomy 18 (Tri18), four cases (0.44%) of Turner syndrome (45, X), one cases (0.11%) of Klinefelter's syndrome (47, XXY), and one cases (0.11%) with lower X chromosome concentration. Further validation indicated that one case of Tri18 and the case with lower X chromosome concentration were false positive results (0.22%) in NIPT. Furthermore, it was found that the false positive case with lower X chromosome concentration in NIPT was caused by maternal sex chromosomal mosaicism (45, X and 46, XX)., Conclusion: Our findings indicated that maternal mosaicism of sex chromosome could cause discordant sex chromosomal aneuploidies associated with NIPT. We highly recommended that maternal karyotype should be confirmed for the cases with abnormal results in NIPT., (Copyright © 2015. Published by Elsevier B.V.)

Objective: To investigate the efficiency of maternal serum triple screening for the genetic abnormality in second-trimester and the morbidity of adverse pregnancy outcome in false positive results of the test., Methods: A total of 4,680 pregnant women with singleton pregnancies assigned in Obs & Gyn Hospital, Fudan University, underwent triple screening test (alpha fetoprotein, AFP; human chorionic gonadotropin, HCG and unconjugated estriol, uE3) by fluorescence enzyme immunoassay between 2003 and 2005. The valid MoM (Multiples of Median) value of mid-trimester serum AFP, uE3, and hCG and risk assessments was provided by Beckman Coulter Co. when applied in the prenatal Down syndrome screening service. The study compares the incidence of chromosomal abnormalities with Down syndrome in screen positive women and compares to the MoM value established in the literature. The risks of having a fetus with congenital abnormalities or of developing obstetric complications in the screen positive women with their matched controls., Results: The MoM values for the triple tests of our study are similar to established values of literature. Only 51.01% women with pregnancies agree to receive screening. Amniocentesis utilization rate was 55.12% in the screen-positive pregnancies. The false positive rate was 6.89% and the median of maternal age of the women was 28.13 (range 19 to 49) years old. Chromosomal abnormalities were identified in 21 pregnancies, including 9 cases of trisomy 21. The detection rate was 77.77%. Pregnancies with positive screening results had a significantly higher risk of adverse outcomes than those with negative results (P< 0.05). Whereas there was no difference in the incidences of fetal congenital appearance or skeleton abnormality., Conclusion: Adjusting MoM values of local unaffected populations is limited to increasing the detection rate. Because chromosomal defects have variable exhibitions, amniocentesis utilization is still a choice for screen-positive pregnancies. Screen-positive pregnancies had increased risk of chromosomal abnormalities.