Development and validation of a novel panel of 16 STR markers for simultaneous diagnosis of β-thalassemia, aneuploidy screening, maternal cell contamination detection and fetal sample authenticity in PND and PGD/PGS cases

Abstract

Prenatal diagnosis (PND) may be complicated with sample mix-up; maternal cell contamination, non-paternity and allele drop out at different stages of diagnosis. Aneuploidy screening if combined with PND for a given single gene disorder, can help to detect any common aneuploidy as well as aiding sample authenticity and other probable complications which may arise during such procedures. This study was carried out to evaluate the effectiveness of a novel panel of STR markers combined as a multiplex PCR kit (HapScreen™ kit) for the detection of β-thalassemia, aneuploidy screening, ruling in/out maternal cell contamination (MCC), and sample authenticity. The kit uses 7 STR markers linked to β-globin gene (HBB) as well as using 9 markers for quantitative analysis of chromosomes 21, 18, 13, X and Y. Selection of the markers was to do linkage analysis with β-globin gene, segregation analysis and to perform a preliminary aneuploidy screening of fetal samples respectively. These markers (linked to the β-globin gene) were tested on more than 2185 samples and showed high heterozygosity values (68.4–91.4%). From 2185 fetal cases we found 3 cases of non-paternity, 5 cases of MCC, one case of sample mix-up and one case of trisomy 21 which otherwise may have end up to misdiagnosis. This kit was also successfully used on 231 blastomeres for 29 cases of pre-implantation genetic diagnosis (PGD) and screening (PGS). The markers used for simultaneous analysis of haplotype segregation and aneuploidy screening proved to be very valuable to confirm results obtained from direct mutation detection methods (i.e. ARMS, MLPA and sequencing) and aneuploidy screening.

GSK-3 and Tau: A Key Duet in Alzheimer’s Disease

“…Although extrasynaptic NMDARs have been mostly linked to excitotoxicity and cell death [ 170 ], extrasynaptic NMDAR currents are also crucial for efficient LTD [ 171 , 172 , 173 ]. Of note, tau knockout neurons lack NMDA extrasynaptic currents [ 174 ]. This may contribute to LTD deficits exhibited in tau knockout mice, which also show spatial reversal learning [ 175 ].…”

“…One possibility is that LTD might induce tau relocalization to dendritic shafts and/or spines. Another option, supported by recent evidence, is that some tau is physiologically present in dendritic spines [ 174 ], and that this proportion of tau is the one that mediates LTD, exerting its function in synaptic plasticity. In addition, mechanical injuries of neurons lead to mislocalization of tau to dendritic spines and tau-dependent synaptic dysfunction, mediated by GSK-3 (and CDK5) tau phosphorylation [ 179 ].…”

A Decade of Molecular Preimplantation Genetic Diagnosis of 350 Blastomeres for Beta-Thalassemia Combined with HLA Typing, Aneuploidy Screening and Sex Selection in Iran

“…SixSTR markers anking beta-globin gene were used for beta-globing gene segregation (11). 35 STR markers surrounding the HLA class I, II and III regions as well as its telomeric and centromeric regions on chromosome 6 were selected for human leukocyte antigen (HLA) typing.…”

“…Each STR marker was individually checked for each family for being informative and selected STR markers and exon/s containing the causative mutation/s were ampli ed in two consecutive reactions using nested PCR method (11).…”

“…In each PGD cycle, only markers with high allele frequency were used to enable us to determine haplotype and segregation pattern. Finally 6 STRs were kept and made to become ready to be used in PGD and PND cases in our centre (11). We had 22 couples who referred to our centre for detecting beta-thal only, and 7 pregnancies have been achieved…”