The assessment of combined first trimester screening in women of advanced maternal age in an Asian cohort.

INTRODUCTION: First trimester screening (FTS) is a validated screening tool that has been shown to achieve detection rates of 84%-90% for trisomies 21, 18 and 13. However, its effectiveness for different maternal ages has not been assessed. The present study aimed to assess the performance of FTS in an Asian population, and to compare its effectiveness in older (≥ 35 years) and younger (< 35 years) women. The potential use of noninvasive prenatal test (NIPT) as a contingent screening test is also examined. METHODS: Data on cases of FTS performed on singleton pregnancies over a six-year period was collated from two Singapore maternal centres, National University Hospital and Singapore General Hospital. Cases that had a 1:250 risk of trisomy were considered to be screen-positive. Pregnancy outcomes were obtained from birth records or karyotype test results. RESULTS: From 10,289 FTS cases, we obtained a sensitivity of 87.8%, a specificity of 97.6%, a false positive rate of 2.4% and a false negative rate of 0.06% for the detection of aneuploidy. The overall detection rate for trisomy 21 was 86.5%-85.7% for older women and 87.5% for younger women. The mean number of invasive tests required per case of trisomy 21 was 9.3 in younger women, 8.6 in older women and 13.5 in women with intermediate risk (1:250-1,000). CONCLUSION: While the performance of FTS was similar in younger and older women, more invasive procedures were required to diagnose trisomy 21 in women with intermediate risk. It may be advantageous to offer contingent NIPT to this group of women to reduce the risk of iatrogenic fetal loss.

Modified cIg-FISH protocol for multiple myeloma in routine cytogenetic laboratory practice.

The International Myeloma Working Group recommends that fluorescence in situ hybridization (FISH) be performed on specifically identified plasma cells (PC). This is because chromosomal abnormalities are not frequently detected by traditional karyotyping due to the low proliferative rate of PC in multiple myeloma (MM). Conventional FISH enhances the sensitivity but lacks the specificity, as it does not distinguish PC from other hematopoetic cells. To fulfill this recommendation, PC need to be selected either by flow cytometry or immunomagnetic bead-based PC sorting or by concomitant labeling of the cytoplasmic immunoglobulin light chain, which allows for unambiguous identification. These techniques require expertise, time, and funding and are not easily incorporated into the routine workflow of the cytogenetic laboratory. We have modified and refined the technique using fixed cell pellets to achieve nicely separated and easily identifiable PC. With immunostaining and subsequent FISH (i.e., cytoplasmic immunoglobulin FISH, cIg-FISH), this technique can be easily incorporated into every cytogenetic laboratory. Twenty samples from patients with MM were subjected to routine FISH, cIg-FISH, and chromosomal karyotyping and the results were compared. Three FISH probes, which enabled detection of the t(4;14), t(14;16) and deletion of TP53, were used to validate this modified technique successfully.

Same-day prenatal diagnosis of common chromosomal aneuploidies using microfluidics-fluorescence in situ hybridization.

Rapid molecular prenatal diagnostic methods, such as fluorescence in situ hybridization (FISH), quantitative fluorescence-PCR, and multiplex ligation-dependent probe amplification, can detect common fetal aneuploidies within 24 to 48 h. However, specific diagnosis or aneuploidy exclusion should be ideally available within the same day as fetal sampling to alleviate parental anxiety. Microfluidic technologies integrate different steps into a microchip, saving time and costs. We have developed a cost-effective, same-day prenatal diagnostic FISH assay using microfluidics. Amniotic fluids (1-4 mL from 40 pregnant women at 15-22 weeks of gestation) were fixed with Carnoy's before loading into the microchannels of a microfluidic FISH-integrated nanostructured device. The glass slides were coated with nanostructured titanium dioxide to facilitate cell adhesion. Pretreatment and hybridization were performed within the microchannels. Fifty nuclei were counted by two independent analysts, and all results were validated with their respective karyotypes. Of the 40 samples, we found three cases of fetal aneuploidies (trisomies 13, 18, and 21), whereas the remaining 37 cases were normal. Results were concordant with their karyotypes and ready to be released within 3 h of sample receipt. Microfluidic FISH, using 20-fold less than the recommended amount of probe, is a cost-effective method to diagnose common fetal aneuploidies within the same day of fetal sampling.

Follicular lymphomas with plasmacytic differentiation include two subtypes.

Follicular lymphomas with plasmacytic differentiation were described more than two decades ago. However, the possibility that some of these reported cases are marginal zone lymphomas or composite lymphomas must be considered. In addition, it is also uncertain whether follicular lymphomas with plasmacytic differentiation have any unique cytogenetic or other features. Therefore, fluorescence immunophenotypic and interphase cytogenetic analysis of 14 well-characterized follicular lymphomas with plasmacytic differentiation was performed using a CD138 antibody to identify the plasma cells and with BCL2, BCL6, IGH@ and MALT1 break-apart probes and a chromosome 12 centromeric probe. CD10 was expressed in 12/14 cases, BCL6 in 12/12 cases and BCL2 in 12/14 cases. At least one cytogenetic abnormality was identified in 12/14 cases. The same abnormality was present in both the plasmacytic (CD138+) and non-plasmacytic (CD138-) component in all 10 evaluable cases. BCL2 rearrangements were present in seven cases (5 IGH@ rearranged, 1 IGH@-not rearranged, 1 IGH@-not evaluable), BCL6 rearrangement in two (1 also with BCL2/IGH@ rearrangement), +12 in 1, +MALT1 without +18 in 1, IGH@ rearrangement without other abnormalities in 1 and IGH@ rearranged or partially deleted in 1 case. No cases showed +BCL6 (3q27) or a MALT1 rearrangement. All six cases with an isolated BCL2 rearrangement had predominantly interfollicular plasmacytic cells whereas, 6/7 cases without the translocation had concentrations of intrafollicular or perifollicular plasmacytic cells (P<0.005), as did the case with BCL2 and BCL6 translocations. These results support the existence of bona fide follicular lymphomas with plasmacytic differentiation and support the clonal relationship of the neoplastic lymphoid and plasma cells in at least most of these cases. The differential distribution of the plasma cells, specifically in relation to the presence or absence of an isolated BCL2 rearrangement suggests that the latter cases may be distinctive, sharing some features with marginal zone lymphomas.

Prenatal detection of isochromosome 21 by QF-PCR. A comparison between FISH and traditional karyotyping.

OBJECTIVE: To compare rapid aneuploidy diagnostic tests with traditional karyotyping in the prenatal detection of Down syndrome due to isochromosome 21. METHODS: Quantitative fluorescence PCR (QF-PCR) and fluorescent in situ hybridization (FISH) for chromosomes 13, 18, 21, X and Y were performed on uncultured amniotic fluid, followed by routine karyotyping. chromosomal and microsatellite analysis of peripheral blood from parents was also carried out. RESULTS: The QF-PCR screening showed a trisomic diallelic pattern for 5 of 6 markers spanning the long arm of chromosome 21. FISH showed 3 signals in the interphase cells for the region 21q22.13-q22 during LSI 21 probe mapping. Cultured amniotic fluid revealed an isochromosome 21 resulting in a 46,XX,i(21)(q10),+21 karyotype. Parental microsatellite analysis proved that the isochromosome was paternal in origin. CONCLUSION: The most informative analytical tool in this case appears to be QF-PCR, although a combination of QF-PCR and karyotyping provided the most evidence.

Characterization of breakpoints in the GABRG3 and TSPY genes in a family with a t(Y;15)(p11.2;q12).

We report the clinical, cytogenetic, and molecular findings in a family in which a t(Y;15)(p11.2;q12) is segregating. The Y chromosome breakpoint disrupts the DYZ5 sequence containing the TSPY genes that are exclusively expressed in the testes while the chromosome 15 breakpoint is within the GABRG3 gene. The father and his son who both carried the balanced form of the translocation are clinically normal. A daughter who carried the der Y had the clinical features of Prader-Willi syndrome while a son who carries the der 15 has mild developmental delay and hypogonadism. The relationship of the translocation to the clinical phenotypes is discussed.

FISH analysis of Y chromosome long arm deletions in subfertile men considering ICSI. A report of two cases.

BACKGROUND: Men with Y chromosome long arm deletions, resulting in infertility, form a very significant group of patients, with a view to treatment. With recent advances in assisted reproductive techniques, it is expected that if these patients undergo intracytoplasmic sperm injection, their male offspring will inherit the same deleted regions of Y chromosomes. Hence, characterization of these deleted Y regions provides information, allowing patients to make informed decisions about reproduction. Fluorescence in situ hybridization (FISH), with probes along the Y chromosome, is very helpful in identification of the exact breakpoints. CASES: Two men with complaints of infertility on examination showed low or no sperm in their semen samples. Routine cytogenetic analysis of the peripheral blood showed a small marker chromosome. This marker was identified as the Y chromosome by FISH. Subsequently, other probes along the Y long arm were used to characterize the extent of the deletion. CONCLUSION: With the use of fluorescence-labelled probes, it was possible to identify the extent of the Y chromosome deletion. The distal Yq11 region had been lost in both patients, resulting in oligospermia and azoospermia. Characterizing markers by FISH gave good guidelines to the patients about the possible effects on offspring, allowing them to make appropriate decisions.