Chromosomal abnormalities study for anembryonic pregnancy by BACs-on-Beads technique

OBJECTIVE

This study evaluated the BACs-on-Beads™ (BoBs) efficiency assay in detecting chromosomal anomalies in products of conception (POC) specimens associated with anembryonic pregnancy (AP) among Thai pregnant women.

METHOD

Retrospective analysis applied the BoBs™ assay to examine AP samples from 2010 to 2022. The incidences of AP with chromosomal abnormalities were reported.

RESULT

Assessment of villi from anembryonic pregnancy samples found normal chromosome complement in 50% of the cases, while the remainder showed chromosomal abnormalities. Trisomy 16 was found in 15% of the cases and trisomies 22, 15, and 19 in 9.6%, 3.8%, and 3.8%, respectively. Advanced maternal age was associated with a higher incidence of aneuploidy.

CONCLUSION

The BoBs™ assay effectively detected diverse chromosomal abnormalities in villi samples from POC. The diagnostic utility of the BoBs™ assay was highlighted in identifying chromosomal irregularities in AP cases. Trisomy 16 possessed the most chromosomal abnormalities in the AP samples.

Committed change of real-time quantitative PCR to droplet digital PCR for monitoring BCR::ABL1 transcripts in tyrosine kinase inhibitor treated CML

OBJECTIVES

We performed a feasibility study of an FDA-approved commercial ddPCR assay to measure BCR::ABL1 in CML patients treated using TKI therapy.

METHODS

Assay performance of standard RQ-PCR and commercially available FDA-approved ddPCR were compared to measure BCR::ABL1 p210 transcripts in RNA samples from 100 CML patients who received TKI therapy.

RESULTS

%BCR::ABL1/ABL1IS levels obtained from both methods were not statistically significant difference after normalization with batch-specific conversion factor (p = 0.0651). The correlation and agreement of %BCR::ABL1/ABL1IS between the two assays were high. Molecular response stratification data showed 56% concordance between RQ-PCR and ddPCR, and 37% higher residual disease detection using ddPCR. Furthermore, 21.21% (7/33) of RQ-PCR undetectable samples were detected by ddPCR, representing high sensitivity to quantify the low abundance of BCR::ABL1 transcripts.

CONCLUSION

ddPCR was proven to be a highly sensitive method with the potential to overcome some limitations of traditional RQ-PCR, and has the potential of being a valuable tool for monitoring BCR::ABL1 transcripts in CML during TKI therapy. (163 words).

Incidence and Types of Fetal Chromosomal Abnormalities in First Trimester of Thai Pregnant Women between Miscarriages and Intrauterine Survivals

Abortion is a common pregnancy complication. Fetuses with several types of chromosomal abnormalities are aborted during the first trimester, while others have a better chance of surviving. This research aims to study and compare the incidence and types of fetal chromosomal abnormalities during the first trimester of Thai pregnant women between miscarriages and intrauterine survivals. Cytogenetic and BACs-on-Beads™ assays were assessed from 2010 to 2020 in Ramathibodi Hospital using first trimester samples of 265 chorionic villi as a retrospective study. Chromosomal abnormalities were observed in 135 cases (50.94%) including 38.11% miscarriages and 12.83% intrauterine survivals. In total, 75.56% single autosomal trisomies, 18.52% sex chromosome aneuploidies, 5.19% double aneuploidies, and 0.74% structural abnormalities were detected. In miscarriages, all chromosomes were involved in abnormalities except chromosomes 1, 5, 8, 9, 11, and 17, while survivals had only trisomy 13, 18, 21, and sex chromosome aneuploidy. Trisomy 16 and 18 were the most common abnormalities in miscarriages and intrauterine survivals, respectively. The highest rate of chromosomal aberrations was demonstrated in 8-9+6 and 12-13+6 weeks of gestation in miscarriages and intrauterine survivals, respectively. Correlation between chromosomal abnormalities and maternal age <35 years and ≥35 years was significant (p < 0.05) in intrauterine survival and first trimester groups.

Performance of the MLPA technique for detecting common mutations in Leber hereditary optic neuropathy

Leber hereditary optic neuropathy (LHON) causes painless vision loss resulting from mitochondrial DNA (mtDNA) mutation. Over 95% of LHON cases result from one of three mtDNA point mutations (m.3460G>A, m.11778G>A, and m.14484T>C). There is no established cure for LHON; early and accurate diagnosis would enable patients to be given appropriate treatments leading to a reduction of the disease progression. To increase the accessibility to molecular genetic testing for LHON, an accurate and cost-effective technique is required. The purpose of this study was to evaluate the accuracy of multiplex ligation-dependent probe amplification (MLPA) for detecting the three common mutations in 18 LHON blood specimens. Validation of the results using direct DNA sequencing technology proved that the MLPA technique had 100% accuracy, with no false-positive results. This study demonstrates that MLPA could provide a highly accurate, economical, and widely accessible technique for routine molecular genetic testing for mitochondrial disorders.

Characterization of five complete Cyrtodactylus mitogenome structures reveals low structural diversity and conservation of repeated sequences in the lineage

Mitochondrial genomes (mitogenomes) of five Cyrtodactylus were determined. Their compositions and structures were similar to most of the available gecko lizard mitogenomes as 13 protein-coding, two rRNA and 22 tRNA genes. The non-coding control region (CR) of almost all Cyrtodactylus mitogenome structures contained a repeated sequence named the 75-bp box family, except for C. auribalteatus which contained the 225-bp box. Sequence similarities indicated that the 225-bp box resulted from the duplication event of 75-bp boxes, followed by homogenization and fixation in C. auribalteatus. The 75-bp box family was found in most gecko lizards with high conservation (55-75% similarities) and could form secondary structures, suggesting that this repeated sequence family played an important role under selective pressure and might involve mitogenome replication and the likelihood of rearrangements in CR. The 75-bp box family was acquired in the common ancestral genome of the gecko lizard, evolving gradually through each lineage by independent nucleotide mutation. Comparison of gecko lizard mitogenomes revealed low structural diversity with at least six types of mitochondrial gene rearrangements. Cyrtodactylus mitogenome structure showed the same gene rearrangement as found in most gecko lizards. Advanced mitogenome information will enable a better understanding of structure evolution mechanisms.