Use of cell-free non-invasive prenatal testing in pregnancies affected by placental mosaicism.

OBJECTIVE: To evaluate cell-free non-invasive prenatal testing (cfNIPT) in pregnancies affected by mosaicism. METHOD: We assessed paired cfNIPT and chorionic villus sample (CVS) results from the same pregnancies in a case series of mosaicism detected in Central and North Denmark Regions from April 2014 to September 2018. Indications for the clinically obtained CVS, pregnancy markers and outcome were retrieved from The Danish Fetal Medicine Database. RESULTS: Mosaicisms in CVS involved common aneuploidy, n = 14; sex chromosomal aneuploidies, n = 14; rare autosomal trisomies (RATs), n = 16 and copy number variants (CNVs) >5Mb, n = 9. Overall, 24/53 (45.3%; CI 95%: 31.8%-59.4%) of cases with mosaicism were detected by cfNIPT; highest for RATs (56%) and lowest for CNVs (22%). CfNIPT more commonly detected high-level than low-level mosaic cases (p = 0.000). CfNIPT detected 7/16 (43.8%; CI 95%: 21%-69%) clinically significant mosaic cases, either true fetal mosaicism or confined placental mosaicisms with adverse pregnancy outcome. There was a trend toward a higher risk for adverse outcome in pregnancies where mosaicism was detected by cfNIPT compared to pregnancies where mosaicism was not detected by cfNIPT (p = 0.31). CONCLUSION: CfNIPT has a low detection rate of mosaicism, including pregnancies with clinically significant mosaicism. However, abnormal cfNIPT results may be a predictor of adverse pregnancy outcomes.

Incidental finding of maternal malignancy in an unusual non-invasive prenatal test and a review of similar cases.

We present a clinical case where a complex abnormal non-invasive prenatal test (NIPT) result in a research project revealed carcinoma of the breast in the pregnant woman. Furthermore, the NIPT result did not demonstrate the same fetal chromosomal aberration as the chorion villus sample. A literature search for similar cases was performed identifying 43 unique cases, where abnormal NIPT results were related to maternal malignancy. Malignancy is a rare but important cause of complex abnormal non-invasive prenatal test (NIPT) results and should be considered when fetal karyotype and abnormal NIPT results are discordant. Furthermore, a follow-up invasive sample is essential for correct fetal diagnosis when abnormal NIPT results are found.

Trisomy 8 mosaicism in the placenta: A Danish cohort study of 37 cases and a literature review.

OBJECTIVE: To evaluate the risk of fetal involvement when trisomy 8 mosaicism (T8M) is detected in chorionic villus samples (CVS). METHODS: A retrospective descriptive study of registered pregnancies in Denmark with T8M in CVS identified through a database search and a review of published cases of T8M found through a systematic literature search and inclusion of cross references. Pregnancies with T8M in CVS and no additional numerical chromosomal aberrations were included. RESULTS: A total of 37 Danish cases and 60 published cases were included. T8M detected in a CVS was associated with fetal involvement in 18 out of 97 pregnancies (18.6% [95%CI: 11.4-27.7]). Eight out of 70 (11.4% [95%CI: 5.1-21.3]) interpreted prenatally to be confined placental mosaicism (CPM) were subsequently found to be true fetal mosaicisms (TFM). CONCLUSION: T8M detected in CVS poses a significant risk of fetal involvement, and examination of amniotic fluid (AF) and/or fetal tissue should be offered. However, a normal result of AF still has a considerable residual risk of fetal involvement. Genetic counselling at an early gestational age is essential, and follow-up ultrasonography should be performed to predict fetal involvement if possible.

The spectrum of intermediate SCN8A-related epilepsy.

OBJECTIVE: Pathogenic variants in SCN8A have been associated with a wide spectrum of epilepsy phenotypes, ranging from benign familial infantile seizures (BFIS) to epileptic encephalopathies with variable severity. Furthermore, a few patients with intellectual disability (ID) or movement disorders without epilepsy have been reported. The vast majority of the published SCN8A patients suffer from severe developmental and epileptic encephalopathy (DEE). In this study, we aimed to provide further insight on the spectrum of milder SCN8A-related epilepsies. METHODS: A cohort of 1095 patients were screened using a next generation sequencing panel. Further patients were ascertained from a network of epilepsy genetics clinics. Patients with severe DEE and BFIS were excluded from the study. RESULTS: We found 36 probands who presented with an SCN8A-related epilepsy and normal intellect (33%) or mild (61%) to moderate ID (6%). All patients presented with epilepsy between age 1.5 months and 7 years (mean = 13.6 months), and 58% of these became seizure-free, two-thirds on monotherapy. Neurological disturbances included ataxia (28%) and hypotonia (19%) as the most prominent features. Interictal electroencephalogram was normal in 41%. Several recurrent variants were observed, including Ile763Val, Val891Met, Gly1475Arg, Gly1483Lys, Phe1588Leu, Arg1617Gln, Ala1650Val/Thr, Arg1872Gln, and Asn1877Ser. SIGNIFICANCE: With this study, we explore the electroclinical features of an intermediate SCN8A-related epilepsy with mild cognitive impairment, which is for the majority a treatable epilepsy.

Preferences for prenatal testing among pregnant women, partners and health professionals.

INTRODUCTION: Cell-free DNA testing (cfDNA testing) in maternal plasma has recently been implemented in Danish healthcare. Prior to that we wanted to evaluate the preferences among pregnant women, partners and health professionals regarding cfDNA testing compared with invasive prenatal diagnostics. METHODS: Responders were recruited at public hospitals in the Central and North Denmark Regions. Stated preferences for prenatal testing were obtained through an online questionnaire incorporating a discrete choice experiment. Test choices differed according to attributes such as risk of miscarriage (none or small) and genetic information provided by the test; simple (Down syndrome only) or comprehensive (chromosomal abnormalities beyond Down syndrome). RESULTS: No risk of miscarriage was the key attribute affecting the preferences of women (n = 315) and partners (n = 102). However, women with experiences of invasive testing placed more emphasis on comprehensive genetic information and less on risk of miscarriage compared with other women. Likewise, foetal medicine experts, obstetricians and sonographers (n = 57) had a greater preference for comprehensive genetic information than midwives who were not directly involved in counselling for prenatal testing (n = 48). CONCLUSIONS: As safety seems to affect the majority of pregnant couples' choice behaviour, thorough pre-test counselling by trained health professionals is of paramount importance. FUNDING: Aarhus University and The Foundation of 17-12-1981. TRIAL REGISTRATION: This study was registered with the Danish Data Protection Agency (1-16-02-586-13/ 2007-58-0010).

Prenatal diagnosis of Nager syndrome in a 12-week-old fetus with a whole gene deletion of SF3B4 by chromosomal microarray.

Less than one hundred cases of the acrofacial dysostosis, Nager syndrome, have been described. The cardinal features of Nager syndrome are micrognathia, midface retrusion and limb malformations, predominately of the radial ray of upper extremities. Within the past three years haploinsufficiency of SF3B4 has been confirmed as the major cause of Nager syndrome. Different loss-of-function point-mutations in SF3B4 have been found in approximately 2/3 of patients diagnosed with Nager syndrome. Whole gene deletions of SF3B4 have also been suggested to be the cause of Nager syndrome in SF3B4 point mutation negative patients. Only four prenatal cases displaying Nager-like features in the 2nd or 3rd trimester which have been genetically confirmed with SF3B4 point-mutation after birth have been described. We report a case of a 12-week-old fetus with micrognathia, malformed wrists, bilateral club foot and short long bones diagnosed prenatally by chromosomal microarray with a de novo 0.4 Mb deletion at chromosome 1q21.2 involving SF3B4. To our knowledge, this is the first report of Nager syndrome caused by a SF3B4 whole gene deletion. The case presented also shows that high-resolution chromosomal microarray in early pregnancy can confirm Nager syndrome caused by SF3B4-deletion prenatally.