China
Africa
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Being Disabled and Contemplating Disabled Children
Published in Joel Michael Reynolds, Christine Wieseler, The Disability Bioethics Reader, 2022
There is now an array of means through which potential parents can not only identify, but often choose, the characteristics of their future child, at least in the sense of choosing between different options. Technologies of prenatal diagnosis (PND) range from ultrasound, through biochemical or genetic analysis of fetal tissue obtained via amniocentesis or chorionic villus sampling (CVS), to non-invasive prenatal testing (NIPT), which tests fetal tissue from a sample of the mother’s blood. Coupled with in vitro fertilization, preimplantation genetic diagnosis (PGD) makes it possible to genetically profile in vitro-produced embryos before deciding which one(s) to transfer for pregnancy. Most recently, attention has turned to the future and more speculative possibilities of genome editing: a different mode of genetic reproductive selection that I discuss later on.
Carrier Screening For Inherited Genetic Conditions
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Whitney Bender, Lorraine Dugoff
Women who accept fragile X premutation screening should be offered FMR-1 DNA mutation analysis after genetic counseling about the risks, benefits, and limitations of screening [25]. All identified carriers should be referred for follow-up genetic counseling. Diagnostic modalities for prenatal diagnosis (including chorionic villus sampling [CVS] and amniocentesis) should be discussed.
Sickle Cell Disease
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Offer laboratory evaluation to father of the baby (CBC, hemoglobin electrophoresis). Offer genetic counseling if father is positive for HbS. If father is positive for HbS, offer prenatal diagnosis via chorionic villous sampling or amniocentesis through direct DNA analysis (polymerase chain reaction). Interestingly, the vast majority of women at risk of an affected fetus decline prenatal diagnosis.
Clinical application of noninvasive prenatal testing in twin pregnancies: a single-center experience
Published in Expert Review of Molecular Diagnostics, 2023
Yanmei Luo, Bin Hu, Yang Long, Yan Pan, Lupin Jiang, Wei Xiong, Huanhuan Xu, Liang Xu, Dan Wang
According to the described process of NIPT, we performed an observational study on a large sample of twin pregnancies. Ten pregnant women were found to be at a high risk of fetal chromosomal aneuploidies, which included seven T21 fetuses, two T18 fetuses, and one T13 fetus. They were identified by chromosome karyotype analysis of fetuses and postnatal newborns, yielding a screen positive rate of 0.6%. This is lower than a previous study showing 1.9%~8.1% of the positive screen incidence of aneuploidy in twins [35,37]. One reason may be that patients with high risk would be suggested by physicians to undergo prenatal diagnosis. The second reason may be that China’s two-child policy has led to a significant increase in pregnant women of advanced age, but the current NIPT guideline recommends that NIPT should be used with caution in twin pregnancies when the maternal age exceeds 35 [40].
Research Progress of Cell-Free Fetal DNA in Non-Invasive Prenatal Diagnosis of Thalassemia
Published in Hemoglobin, 2023
Dewen Liu, Chen Nong, Fengming Lai, Yulian Tang, Taizhong Wang
In order to achieve prenatal diagnosis without using a family proband, Grace et al. first proposed linking reading sequencing technique based on microfluidic technology, which can be directly used to construct parental haplotypes [29]. Currently, this technique has been applied to the NIPD of congenital adrenal hyperplasia (CAH) [30], thalassemia [31] and X-linked recessive disease–DMD [32]. Although this technique allows the direct construction of parental haplotypes, it is complex and has a longer experimental cycle than noninvasive delivery diagnosis based on probands [33]. Paula et al. proposed a targeted locus amplification (TLA) technique, which is distinct from targeted re-sequencing method, which can also be used to construct haplotypes without using pedigree probands [34]. Then Carlo et al. utilized this technique to construct the parental haplotype of β-thalassemia [35]. The researchers also proposed different sequencing techniques such as semiconductor sequencing [36] and nanopore sequencing [37] combined with RHDO for the diagnosis of β-thalassemia. Although the above methods can achieve the diagnosis of β-thalassemia, the experimental process is equally complex and difficult to apply in the clinical setting.
Severe Hb H Disease Caused by Hb Zürich–Albisrieden (HBA1: c.178G>C): Another Case Report
Published in Hemoglobin, 2022
Shao-Min Wu, Su-Ran Huang, Chan Li, Gui-Lan Chen, Dong-Zhi Li
To the best of our knowledge, all reported cases carrying Hb Zürich–Albisrieden, either in the form of Hb H disease, homozygous or in combination with other nondeletional α-thal mutations, presented with a phenotype of severe thalassemia. These findings indicate that Hb Zürich–Albisrieden is a highly pathogenic nondeletional α-thal allele, as indicated in the ITHANET (ID 3280) and ClinVar (ID 993066) databases. As all of the previously reported heterozygotes had mild erythrocytosis, microcytosis, and hypochromia, carriers can be screened by current red blood cell (RBC) indices-based thalassemia screening programs. Detection of nondeletional α-thal variants is important for any thalassemia control programs in Southern China because of the high prevalence of α0-thal [11]. DNA analysis is necessary for a definitive diagnosis, especially in individuals whose partner has already been diagnosed as an α0-thal carrier. In cases at-risk for Hb H/Hb Zürich–Albisrieden, genetic counseling should be offered to the couples, considering the more severe phenotypes of affected individuals. Prenatal diagnosis should be recommended in early gestation.