Beyond Trisomy 21: Additional Chromosomal Anomalies Detected through Routine Aneuploidy Screening

The importance of the trisomy 21 local cutoff value evaluation for prenatal screening in the second trimester of pregnancy

OBJECTIVE

The aim of this work was to compare different local cutoff values (LCV) and inline cutoff values (ICV) in pregnant women in the second trimester at high risk for carrying fetuses with trisomy 21.

METHODS

This retrospective cohort study analyzed prenatal screening outcomes in pregnant women (n = 311,561). The receiver operating characteristic curve was used to evaluate the diagnostic significance of the trisomy 21 risk value, alpha-fetoprotein, and free beta human chorionic gonadotropin multiple of the median for predicting trisomy 21 risk. The cutoff value corresponding to the maximal Youden index was taken as the LCV. The screening efficiency of both cutoff values was compared.

RESULTS

The LCV cutoff value was lower than the ICV cutoff value (1/643 vs 1/270). The sensitivity increased by 19.80%, the positive predictive value decreased by 0.20%, and the false-positive rate increased by 6.50%.

CONCLUSION

The LCV should be used to determine trisomy 21 risk, which can increase the detection rate of trisomy 21 in the second trimester.

Termination of pregnancy for foetal indication in the French context analysis of decision-making in a Multidisciplinary Centre For Prenatal Diagnosis

OBJECTIVE

In France, termination of pregnancy (TOP) for medical reasons is legal, regardless of the term, after authorisation by a Multidisciplinary Centre for Prenatal Diagnosis (MCPD). This study analyses the elements supporting the TOP decision-making process faced with a foetal pathology.

STUDY DESIGN

Medical records of one MCPD were analysed for the period 2013 and 2014 and semi-structured interviews with MCPD members were conducted.

RESULTS

Out of 265 files concerning foetal indications, all but one resulted in a decision for TOP. The main indications in number for TOP were malformations and chromosomal abnormalities. For indications such as trisomy 21, authorisations are generally given without discussion. Our results underline the importance that professionals attach to the collegiality of decisions, particularly in situations of uncertainty.

CONCLUSION

This study provides information about the activity of MCPDs within the field of prenatal diagnosis and shows the importance of these structures in supporting women and couples whilst respecting their autonomy. At present, the role of the MCPD is in the process of evolving and could become an information and advisory board for women, based on collegial expertise to guide their decision-making.

Triploidy in a Live-Born Extremely Low Birth Weight Twin: Clinical Aspects

Triploidy is a rare chromosomal aberration characterized by a karyotype with 69 chromosomes. Triploid fetuses usually are miscarried in early pregnancy. We present a case of a triploid twin and a genetically unaffected co-twin, conceived through in vitro fertilization. A discordant growth was registered at 20 weeks of gestation. Cesarean section was performed at 355/7 gestational week. The second twin was extremely growth restricted female (780 g) with oligohydramnios and severe respiratory distress, and died at 20 hours of age. The autopsy revealed unilobar left lung, bilobar right lung, and cysts of the terminal bronchioles. Quantitative fluorescent polymerase chain reaction detected triploidy compatible pattern. So, early intrauterine growth restriction may be a sign of triploidy, which must be proven by pre or postnatal genetic testing.

CNV Radar: an improved method for somatic copy number alteration characterization in oncology

Background

Cancer associated copy number variation (CNV) events provide important information for identifying patient subgroups and suggesting treatment strategies. Technical and logistical issues, however, make it challenging to accurately detect abnormal copy number events in a cost-effective manner in clinical studies.

Results

Here we present CNV Radar, a software tool that utilizes next-generation sequencing read depth information and variant allele frequency patterns, to infer the true copy number status of genes and genomic regions from whole exome sequencing data. Evaluation of CNV Radar in a public multiple myeloma dataset demonstrated that CNV Radar was able to detect a variety of CNVs associated with risk of progression, and we observed > 70% concordance with fluorescence in situ hybridization (FISH) results. Compared to other CNV callers, CNV Radar showed high sensitivity and specificity. Similar results were observed when comparing CNV Radar calls to single nucleotide polymorphism array results from acute myeloid leukemia and prostate cancer datasets available on TCGA. More importantly, CNV Radar demonstrated its utility in the clinical trial setting: in POLLUX and CASTOR, two phase 3 studies in patients with relapsed or refractory multiple myeloma, we observed a high concordance rate with FISH for del17p, a risk defining CNV event (88% in POLLUX and 90% in CASTOR), therefore allowing for efficacy assessments in clinically relevant disease subgroups. Our case studies also showed that CNV Radar is capable of detecting abnormalities such as copy-neutral loss of heterozygosity that elude other approaches.

Conclusions

We demonstrated that CNV Radar is more sensitive than other CNV detection methods, accurately detects clinically important cytogenetic events, and allows for further interrogation of novel disease biology. Overall, CNV Radar exhibited high concordance with standard methods such as FISH, and its success in the POLLUX and CASTOR clinical trials demonstrated its potential utility for informing clinical and therapeutic decisions.

Nicht invasive Pränataldiagnostik mittels molekulargenetischer Tests (NIPT) zur Erkennung der Trisomien 13, 18 und 21

Hintergrund

Molekulargenetische Tests (NIPT) auf Trisomie sind längst Teil der nicht invasiven Pränataldiagnostik (NIPD). In Deutschland wird derzeit geprüft, ob und für wen diese Tests von den gesetzlichen Krankenkassen künftig bezahlt werden sollen.

Fragestellung

(I) Diagnostische Eigenschaften der NIPT zur Entdeckung der Trisomien 13, 18 und 21 und (II) hypothetische Berechnung der möglichen Anwendung der NIPT in verschiedenen Gruppen.

Methoden

(I) Systematische Recherche nach Primärliteratur und systematischen Übersichten in MEDLINE und vier weiteren Datenbanken. Einschlusskriterien: Studien mit schwangeren Frauen, Indextest: NIPT mittels molekulargenetischer Analyse von cffDNA im mütterlichen Blut zur Bestimmung des Trisomie-Risikos; Referenztest: zytogenetische Diagnostik oder postnatale klinische Untersuchung. (II) Orientierende Recherche. Hypothetische Berechnungen für (1) alle schwangeren Frauen nach aktuellem Vorgehen ohne NIPT am Beispiel von Ersttrimesterscreening (ETS), (2) Anwendung bei schwangeren Frauen mit erhöhtem Risiko, z. B. nach vorgeschaltetem auffälligem ETS und (3) NIPT in einer Population mit und ohne erhöhtes Risiko für eine Trisomie.

Ergebnisse

Bei 22 eingeschlossenen Studien lagen die Sensitivität und die Spezifität zur Erkennung der Trisomie 21 bei 99,13 % (95 %-KI: [97,39 %; 99,72 %]) und 99,95 % (95 %-KI: [99,88 %; 99,98 %]). Der mögliche Einfluss von Testversagern blieb bei den Berechnungen unberücksichtigt, womit die Sensitivität oder die Spezifität der NIPT möglicherweise überschätzt wurde. Für die Erkennung der Trisomien 13 und 18 konnte jeweils die Sensitivität nicht robust geschätzt werden.

Diskussion

Bei Frauen mit erhöhtem Risiko können NIPT die Zahl der invasiven Tests und damit der testbedingten Fehlgeburten vermutlich verringern.

Triploidy and Routine Combined First Trimester Pregnancy Screening

BACKGROUND

This report is about a pregnancy with a triploid fetus and underscores the potential of first trimester combined screening to detect this devastating chromosomal aberration earlier in pregnancy. This report is about a pregnancy with a triploid fetus identified from the first trimester combined screening and confirmed by amniocentesis.

METHODS

A 28 year old, G5P2AB2 woman was referred to our clinic at 15 weeks of gestation due to a remarkable decrease of her first trimester double biochemical markers and therefore in the high-risk range for trisomy 13 and 18. The woman underwent amniocentesis which revealed a karyotype of 69,XXX. The parents opted for termination and in post mortem physical examination, a hydrocephalus fetus with marked Intra-Uterine Growth Retardation (IUGR) in addition to syndactyly of third and fourth digits, low set malformed ears, micrognathia and club foot, was seen.

RESULTS

Our results and previous reports highlight the need to consider a somewhat consistent pattern of the first trimester combined screening in a pregnancy with triploidy and underscore the potential of this screening strategy to detect this chromosomal aberration earlier in pregnancy.

CONCLUSION

Early prenatal diagnosis of this syndrome would provide women an opportunity to terminate an affected pregnancy earlier. This is also important in preventing the risks of associated later induced abortion or obstetric complications.