Emily Hardisty

Discordant noninvasive prenatal testing results in a patient subsequently diagnosed with metastatic disease

University of North Carolina at Chapel Hill School of Medicine, Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Chapel Hill, NC 27599, USA Verinata Health, Inc., Department of Clinical Affairs, Redwood City, CA, USA University of North Carolina at Chapel Hill School of Medicine, Department of Pathology and Laboratory Medicine, Chapel Hill, NC, USA *Correspondence to: Neeta L. Vora. E-mail: nvora@med.unc.edu

Mutations in ZIC2 in Human Holoprosencephaly: Description of a Novel ZIC2-Specific Phenotype and Comprehensive Analysis of 157 Individuals

Background Holoprosencephaly (HPE), the most common malformation of the human forebrain, may be due to mutations in genes associated with non-syndromic HPE. Mutations in ZIC2, located on chromosome 13q32, are a common cause of non-syndromic, non-chromosomal HPE. Objective To characterise genetic and clinical findings in patients with ZIC2 mutations. Methods Through the National Institutes of Health and collaborating centres, DNA from approximately 1200 individuals with HPE spectrum disorders was analysed for sequence variations in ZIC2. Clinical details were examined and all other known cases of mutations in ZIC2 were included through a literature search. Results By direct sequencing of DNA samples of an unselected group of unrelated patients with HPE in our NIH laboratory, ZIC2 mutations were found in 8.4% (49/582) of probands. A total of 157 individuals from 119 unrelated kindreds are described, including 141 patients with intragenic sequence determined mutations in ZIC2. Only 39/157 patients have previously been clinically described. Unlike HPE due to mutations in other genes, most mutations occur de novo and the distribution of HPE types differs significantly from that of non-ZIC2 related HPE. Evidence is presented for the presence of a novel facial phenotype which includes bitemporal narrowing, upslanting palpebral fissures, a short nose with anteverted nares, a broad and well demarcated philtrum, and large ears. Conclusions HPE due to ZIC2 mutations is distinct from that due to mutations in other genes. This may shed light on the mechanisms involved in formation of the forebrain and face and will help direct genetic counselling and diagnostic strategies.

A single center’s experience with noninvasive prenatal testing

Purpose:Massively parallel sequencing to detect fetal aneuploidy has high sensitivity and specificity for the detection of trisomies 21, 18, and 13 in high-risk populations. The purpose of our study was to review our institution’s experience with the use of noninvasive prenatal testing for aneuploidy screening.Methods:This was a descriptive study of patients who had undergone noninvasive prenatal testing between January and September 2012 at the UNC Prenatal Diagnosis unit.Results:Two hundred and eight women had undergone noninvasive prenatal testing during the study period. The majority of patients were white (62.9%) and of advanced maternal age (71.2%). The fetal fraction was below the threshold in three obese patients (1.4%). An abnormal noninvasive prenatal test (aneuploidy detected or “unclassified” result) was reported in 6.3% (13/208) of the patients. Noninvasive prenatal testing had a combined sensitivity of 87.5% and specificity of 99.5% for detection of trisomies 21, 18, and 13. There were “unclassified” results in 11.1% (5/45) of the patients. Over the study period, the number of patients requesting noninvasive prenatal testing increased monthly. The rate of amniocenteses significantly declined (8.1% before vs. 5.3% after noninvasive prenatal testing, P < 0.01).Conclusion:An increase in uptake of noninvasive prenatal testing and a significant decline in amniocentesis procedures were observed. The rates of “unclassified,” false-positive, and false-negative results were higher than anticipated based on published preclinical trials.Genet Med 16 9, 681–687.

Prenatal exome sequencing in anomalous fetuses: new opportunities and challenges

PurposeWe investigated the diagnostic and clinical performance of exome sequencing in fetuses with sonographic abnormalities with normal karyotype and microarray and, in some cases, normal gene-specific sequencing.MethodsExome sequencing was performed on DNA from 15 anomalous fetuses and from the peripheral blood of their parents. Parents provided consent to be informed of diagnostic results in the fetus, medically actionable findings in the parents, and their identification as carrier couples for significant autosomal recessive conditions. We assessed the perceptions and understanding of exome sequencing using mixed methods in 15 mother−father dyads.ResultsIn seven (47%) of 15 fetuses, exome sequencing provided a diagnosis or possible diagnosis with identification of variants in the following genes: COL1A1, MUSK, KCTD1, RTTN, TMEM67, PIEZO1 and DYNC2H1. One additional case revealed a de novo nonsense mutation in a novel candidate gene (MAP4K4). The perceived likelihood that exome sequencing would explain the results (5.2 on a 10-point scale) was higher than the approximately 30% diagnostic yield discussed in pretest counseling.ConclusionExome sequencing had diagnostic utility in a highly select population of fetuses where a genetic diagnosis was highly suspected. Challenges related to genetics literacy and variant interpretation must be addressed by highly tailored pre- and posttest genetic counseling.

The utility of a prerequisite ultrasound at 10-14 weeks in cell free DNA fetal aneuploidy screening.

To estimate the frequency of unexpected first‐trimester ultrasound findings that would alter prenatal management in pregnant women eligible for cell‐free (cf) DNA screening because of advanced maternal age (AMA).

Advances in genetic prenatal diagnosis and screening.

Purpose of review Prenatal diagnostic and screening tests are routinely offered to all women in pregnancy. Advances in technology have led to an expansion in available testing. As technology improves, women are facing increasingly complex decisions regarding the quantity and quality of information they wish to have regarding their fetus. Recent findings Professional guidelines support the use of chromosomal microarray analysis as a first-tier test in place of standard karyotype for the evaluation of fetal chromosomes when one or more anomaly is detected by ultrasound. These same guidelines indicate that either chromosomal microarray analysis or standard karyotype can be offered for prenatal diagnosis with a phenotypically normal fetus. Additionally, recent work continues to validate the use of noninvasive prenatal testing for the detection of aneuploidy in the high-risk population. This testing utilizes cell-free DNA in the maternal circulation to predict fetal karyotype with greater sensitivity and specificity than maternal serum screening or first trimester screening. Data continue to accumulate supporting noninvasive prenatal testing use in an all-risk or low-risk population. Additionally, noninvasive prenatal testing is clinically available to screen for a select number of microdeletion syndromes, broadening the scope of population-based screening to include conditions not previously evaluated, although there are limited data available regarding this application. Summary As prenatal diagnosis becomes increasingly complex, there is a need for the education of both patients and providers regarding the benefits and limitations of the testing strategies available to them.

Utility of ultrasound examination at 10–14 weeks prior to cell‐free DNA screening for fetal aneuploidy

To estimate the frequency of unexpected first‐trimester ultrasound findings that would alter prenatal management in pregnant women eligible for cell‐free (cf) DNA screening because of advanced maternal age (AMA).

Cell-Free DNA Screening: Complexities and Challenges of Clinical Implementation.

Screening for fetal aneuploidy in pregnant women using cell-free DNA has increased dramatically since the technology became commercially available in 2011. Since that time, numerous trials have demonstrated high sensitivity and specificity to screen for common aneuploidies in high-risk populations. Studies assessing the performance of these tests in low-risk populations have also demonstrated improved detection rates compared with traditional, serum-based screening strategies. Concurrent with the increased use of this technology has been a decrease in invasive procedures (amniocentesis and chorionic villus sampling). As the technology becomes more widely understood, available, and utilized, challenges regarding its clinical implementation have become apparent. Some of these challenges include test failures, false-positive and false-negative results, limitations in positive predictive value in low-prevalence populations, and potential maternal health implications of abnormal results. In addition, commercial laboratories are expanding screening beyond common aneuploidies to include microdeletion screening and whole genome screening. This review article is intended to provide the practicing obstetrician with a summary of the complexities of cell-free DNA screening and the challenges of implementing it in the clinical setting. Target Audience Obstetricians and gynecologists, family physicians. Learning Objectives After completing this activity, the learner should be better able to understand the complexities of cell-free DNA screening and describe considerations involved in its clinical implementation.

Holoprosencephaly-polydactyly/pseudotrisomy 13: A presentation of two new cases and a review of the literature

Patients with a combination of holoprosencephaly and polydactyly, but with apparently normal chromosomes, may be clinically diagnosed with holoprosencephaly–polydactyly syndrome (HPS), also termed pseudotrisomy 13. However, the criteria for HPS have been controversial since the advent of the diagnostic term, and a clear understanding of the condition lacks definitive delineation. We review the historical and current perspectives on the condition and analyze findings in 40 patients with apparent HPS, including cases from the literature and two previously unreported patients. Overall, our analysis suggests previously unrecognized trends in patients diagnosed with HPS. Specifically, there appears to be a higher prevalence of visceral anomalies, most significantly cardiac and genitourinary, but also with increased gastrointestinal, pulmonary, adrenal, skeletal, and renal abnormalities, in patients with HPS. Although these visceral anomalies may not be essential for the identification of HPS, clinicians should be aware of the presence of such characteristics in these patients to optimize management and help establish etiologies.

Development, Implementation, and Assessment of a Genetics Curriculum Across Institutions

Objective Many residency programs offer limited exposure and minimal didactic time genetics, despite its frequent use in obstetrics and gynecology. The objective of this study was to develop, pilot, and assess a three-module womens health genetics curriculum for residents that was easily transferable between institutions. Methods An interactive three-module genetics curriculum covering basic principles, prenatal screening/diagnosis, and cancer genetics was developed. A pre- and posttests were used to assess improvement in knowledge. Subjective feedback was obtained to assess curricular satisfaction. The data were analyzed with descriptive statistics. Results The curriculum was administered at two institutions. Forty-eight residents attended ≥ 1 session. Twenty completed the pretest, and 23 completed the posttest. At the first institution, using audience response system, the percentage correct per question increased on 10/14 questions between pre- and posttests. All students felt the curriculum was useful and would strongly recommend to other residents. At the second institution, pre/posttests were distributed on paper. Mean scores significantly improved between pre- and posttests (p = 0.007). On the pretest, no residents scored > 70%. However, 8/13 scored > 70% on the posttest (p = 0.002). Instructors at both institutions described the curriculum as easy to use/implement. Conclusion This three-module workshop on womens health genetics was easily implemented across institutions and led to increased knowledge.