Universal chromosomal microarray analysis reveals high proportion of copy-number variants in low-risk pregnancies

OBJECTIVES

To evaluate the yield and utility of the routine use of chromosomal microarray analysis (CMA) for prenatal genetic diagnosis in a large cohort of pregnancies with normal ultrasound (US) at the time of genetic testing, compared with pregnancies with abnormal US findings.

METHODS

We reviewed all prenatal CMA results in our center between November 2013 and December 2018. The prevalence of different CMA results in pregnancies with normal US at the time of genetic testing ('low-risk pregnancies'), was compared with that in pregnancies with abnormal US findings ('high-risk pregnancies'). Medical records were searched in order to evaluate subsequent US follow-up and the outcome of pregnancies with a clinically relevant copy-number variant (CNV), i.e. a pathogenic or likely pathogenic CNV or a susceptibility locus for disease with > 10% penetrance, related to early-onset disease in the low-risk group.

RESULTS

In a cohort of 6431 low-risk pregnancies that underwent CMA, the prevalence of a clinically significant CNV related to early-onset disease was 1.1% (72/6431), which was significantly lower than the prevalence in high-risk pregnancies (4.9% (65/1326)). Of the low-risk pregnancies, 0.4% (27/6431) had a pathogenic or likely pathogenic CNV, and another 0.7% (45/6431) had a susceptibility locus with more than 10% penetrance. Follow-up of the low-risk pregnancies with a clinically significant early-onset CNV revealed that 31.9% (23/72) were terminated, while outcome data were missing in 26.4% (19/72). In 16.7% (12/72) of low-risk pregnancies, an US abnormality was discovered later on in gestation, after genetic testing had been performed.

CONCLUSION

Although the background risk of identifying a clinically significant early-onset abnormal CMA result in pregnancies with a low a-priori risk is lower than that observed in high-risk pregnancies, the risk is substantial and should be conveyed to all pregnant women. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Clinical utility of expanded non-invasive prenatal screening and chromosomal microarray analysis in high-risk pregnancy

OBJECTIVE

To evaluate the utility of expanded non-invasive prenatal screening (NIPS), compared with chromosomal microarray analysis (CMA), for the detection of chromosomal abnormalities in high-risk pregnancies.

METHODS

This was a multicenter retrospective study of singleton pregnancies at high risk for chromosomal abnormality. Patients who underwent expanded NIPS and CMA sequentially during pregnancy from 2015 to 2019 were included in the analysis. Pregnancies with a positive result for sex chromosome aneuploidy were excluded as the full details could not be retrieved. The utility of expanded NIPS and CMA for detection of chromosomal abnormalities in this cohort was compared by assessing the concordance between the results.

RESULTS

Of the 774 included high-risk pregnancies, 550 (71.1%) had a positive NIPS result, while a positive CMA result was detected in 308 (39.8%) cases. The rate of full or partial concordance between NIPS and CMA was 82.2%, 59.6% and 25.0% for trisomies 21, 18 and 13, respectively. For rare aneuploidies and segmental imbalances, NIPS and CMA results were fully or partially concordant in 7.5% and 33.3% of cases, respectively. Copy-number variants < 5 Mb were detected more often by CMA, with an incidence of 7.9% (61/774) compared with 3.1% (24/774) by NIPS. A genetic aberration was detected by CMA in 1 in 17 (5.8%) high-risk pregnancies that had a negative or non-reportable NIPS result.

CONCLUSION

CMA allows for comprehensive detection of genome-wide chromosomal abnormalities in high-risk pregnancies. CMA should be offered instead of expanded NIPS for high-risk pregnancies. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Molecular Analysis of HLA-G in Women with High-Risk Pregnancy and Their Partners with Regard to Possible Complications

The understanding of the molecular and biochemical characteristics of the human leukocyte antigen-G (HLA-G) is important because of the diverse influence of this antigen’s polymorphisms on the course of a pregnancy. The aim of our study was to assess how the variation of the HLA-G allele and the HLA-G 14-bp ins/del polymorphism influence predisposition to a complicated pregnancy. The clinical material consisted of parental pairs with complicated pregnancies (210 women; 190 men). The control group included parental pairs without complications during pregnancy (89 women; 86 men). The study involved isolation of genome DNA from peripheral blood leukocytes, sequencing, and analysis of the 14-bp ins/del polymorphism in the 3′-untranslated region (3′-UTR) of the HLA-G gene based on polymerase chain reaction (PCR). The most common HLA-G allele in the group of women with complicated pregnancies was the HLA-G 10101 allele. There were no statistically significant differences in the frequencies of the 14-bp ins/del polymorphism in the 3′UTR of the HLA-G gene between the groups. Our results suggest that the risk of complications in pregnancy is influenced by the HLA-G 10101, HLA-G 10108, and HLA-G 10106 alleles and is not influenced by the 14-bp ins/del polymorphism in the 3′UTR of the HLA-G gene.

Gene polymorphism associated with endothelial nitric oxide synthase (4VNTR, G894T, C786T) and unexplained recurrent spontaneous abortion risk: A meta-analysis

To evaluate the association between endothelial nitric oxide synthase gene polymorphisms (4VNTR A/B, G894T, C786T) and risk of URSA.Related case-control studies were collected by computers. A meta-analysis was conducted using Stata 12.0 software to assess the strength of association.Altogether 37 articles were examining the relationship between endothelial nitric oxide synthase gene polymorphisms and URSA, among which sixteen (16) studies were related to 4VNTR, twelve (12) to G894T, and nine (9) to C786T, the study suggested that 4VNTR A/B polymorphism was closely connected with URSA risk under all gene models except for recessive model (AA vs. BB + AB). The integrated result which indicated the association between G894T gene mutation and URSA risk had been shown under homozygote (TT vs. GG; OR 1.585, 95%CI 1.175-2.138) and recessive models (TT vs. TG + GG; OR 1.530, 95%CI 1.142-2.052). Considering heterogeneity in the remaining gene models, subgroup analysis was performed on ethnicity, and the results showed that it was the dominant (TT + TG vs. GG; OR 1.585, 95%CI 1.175-2.138) and additive models (T vs. G; OR 1.727, 95%CI 1.372-2.175) of G894T in Asians and the heterozygote model (TG vs. GG; OR 1.015, 95%CI 0.846-1.217) in Caucasians that were associated with URSA (P < .05). Besides C786T gene was significantly connected with URSA under all models except for additive model (T vs. C).It is of great guiding significance for screening out and preventing URSA among high-risk women via testing on 4VNTR A/B, G894T, C786T eNOS under gene models mentioned above which are closely associated with URSA.

Overall evaluation of the clinical value of prenatal screening for fetal-free DNA in maternal blood

OBJECTIVE

To explore the clinical value of prenatal screening for fetal-free DNA in maternal blood.

METHODS

A total of 10,275 maternal blood samples were collected from October 2012 to May 2016 at the prenatal diagnosis center of Changzhou Woman and Children Health Hospital.

RESULTS

Among 10,275 pregnant women accepted noninvasive prenatal testing (NIPT), 9 cases could not get the results after collected the blood second times. The rate of NIPT failure was 0.09%. Seventy-two cases got the NIPT positive results of trisomy 21/trisomy 18/trisomy 13, and the detection rate, specificity, positive predictive value (PPV), and false positive rate were 98.59%, 99.99%, 97.22%, and 0.02%. The top-3 indications of the study were advanced age women (34.90%), high risk (25.22%), and intermediate risk (19.56%). They all had the satisfactory results of NIPT. Fifty-seven pregnant women had the high risk of fetal sex chromosomal aneuploidies (SCA). After informed consent, 33 cases accepted prenatal diagnosis. Eighteen cases were confirmed as sex chromosome aneuploidies. The PPV was 54.54%. Compared with other SCA, the PPV of Turner syndrome was lower. One case was false negative after followed up.

CONCLUSIONS

NIPT showed a broad application prospects for prenatal screening and diagnosis of fetal chromosomal diseases. We should deepen mining and analyzing the clinical data, and explore the use of NIPT more reasonably from the perspective of evidence-based medicine.

A Systematic Review of DNA Methylation and Preterm Birth in African American Women

BACKGROUND

The causes of many cases of preterm birth (PTB) remain enigmatic. Increased understanding of how epigenetic factors are associated with health outcomes has resulted in studies examining DNA methylation (DNAm) as a contributing factor to PTB. However, few studies on PTB and DNAm have included African American women, the group with the highest rate of PTB.

METHODS

The objective of this review was to systematically analyze the existing studies on DNAm and PTB among African American women.

RESULTS

Studies ( N = 10) were limited by small sample size, cross-sectional study designs, inconsistent methodologies for epigenomic analysis, and evaluation of different tissue types across studies. African Americans comprised less than half of the sample in 50% of the studies reviewed. Despite these limitations, there is evidence for an association between DNAm patterns and PTB.

CONCLUSIONS

Future research on DNAm patterns and PTB should use longitudinal study designs, repeated DNAm testing, and a clinically relevant definition of PTB and should include large samples of high-risk African American women to better understand the mechanisms for PTB in this population.

Maternal Race/Ethnicity and Predictors of Pregnancy and Infant Outcomes

Objective. To examine predictors of pregnancy and infant outcomes, including maternal race/ethnicity. Design. Prospective and observational follow-up of high-risk pregnancies and births. Participants. Three hundred fifty-four mothers and their preterm and/or high-risk live-born neonates were closely followed in three tertiary care centers from the prenatal to postnatal periods for potential high-risk and/or preterm births that required neonatal resuscitations. Major Outcome Measures. Pregnancy complications, birth complications, and infant outcomes were examined in conjunction with maternal factors, including preexisting health problems, health behaviors (smoking, alcohol consumption, prenatal visits), and the birth setting (tertiary care centers or community hospitals). Results. About 22% of these infants were transferred into the tertiary care centers from the community hospitals right after birth; the rest were born in the centers. According to regression analyses, predictors of the birth setting were race (White vs. non-White), maternal health behaviors, pregnancy complications, fetal distress, and the presence of congenital defects for infants (p < .001). Predictors for fetal distress included race (Whites) and pregnancy-induced hypertension (p < .003). Predictors for lower birth weight included race (non-Whites), maternal cigarette smoking, pregnancy complications, fetal distress, and congenital defects (p < .001). Infant mortality rate was 3.9% for these high-risk infants, with the highest rate in infants born to Black mothers (8%). Conclusions. There are obvious health disparities among White and non-White women experiencing high-risk pregnancies and births. Future studies are needed to develop interventions targeted to different racial/ethnic groups during pregnancy to reduce preterm and high-risk births.

Clinical evaluation of the IONA test: a non-invasive prenatal screening test for trisomies 21, 18 and 13

OBJECTIVE

To evaluate the clinical accuracy of the IONA® test for aneuploidy screening.

METHODS

This was a multicenter blinded study in which plasma samples from pregnant women at increased risk of trisomy 21 underwent cell-free DNA analysis utilizing the IONA test. For each sample, the IONA software generated a likelihood ratio and a maternal age-adjusted probability risk score for trisomies 21, 18 and 13. All results from the IONA test were compared against accepted diagnostic karyotyping.

RESULTS

A total of 442 maternal samples were obtained, of which 437 had test results available for analysis and assessment of clinical accuracy. The IONA test had a detection rate of 100% for trisomies 21 (n = 43; 95% CI, 87.98-100%), 18 (n = 10; 95% CI, 58.72-100%) and 13 (n = 5; 95% CI, 35.88-100%) with cut-offs applied to likelihood ratio (cut-off > 1 considered high risk for trisomy) and probability risk score incorporating adjustment for maternal age (cut-off ≥ 1/150 considered high risk for trisomy). The false-positive rate (FPR) was 0% for trisomies 18 and 13 with both analysis outputs. For trisomy 21, a FPR of 0.3% was observed for the likelihood ratio, but became 0% with adjustment for maternal age.

CONCLUSION

This study indicates that the IONA test is suitable for trisomy screening in a high-risk screening population. The result-interpretation feature of the IONA software should facilitate wider implementation, particularly in local laboratories, and should be a useful addition to the current screening methods for trisomies 21, 18 and 13.

Clinical experience with single-nucleotide polymorphism-based non-invasive prenatal screening for 22q11.2 deletion syndrome

OBJECTIVES

To evaluate the performance of a single-nucleotide polymorphism (SNP)-based non-invasive prenatal test (NIPT) for the detection of fetal 22q11.2 deletion syndrome in clinical practice, assess clinical follow-up and review patient choices for women with high-risk results.

METHODS

In this study, 21 948 samples were submitted for screening for 22q11.2 deletion syndrome using a SNP-based NIPT and subsequently evaluated. Follow-up was conducted for all cases with a high-risk result.

RESULTS

Ninety-five cases were reported as high risk for fetal 22q11.2 deletion. Diagnostic testing results were available for 61 (64.2%) cases, which confirmed 11 (18.0%) true positives and identified 50 (82.0%) false positives, resulting in a positive predictive value (PPV) of 18.0%. Information regarding invasive testing was available for 84 (88.4%) high-risk cases: 57.1% (48/84) had invasive testing and 42.9% (36/84) did not. Ultrasound anomalies were present in 81.8% of true-positive and 18.0% of false-positive cases. Two additional cases were high risk for a maternal 22q11.2 deletion; one was confirmed by diagnostic testing and one had a positive family history. There were three pregnancy terminations related to screening results of 22q11.2 deletion, two of which were confirmed as true positive by invasive testing.

CONCLUSIONS

Clinical experience with this SNP-based non-invasive screening test for 22q11.2 deletion syndrome indicates that these deletions have a frequency of approximately 1 in 1000 in the referral population with most identifiable through this test. Use of this screening method requires the availability of counseling and other management resources for high-risk pregnancies.

Defects of genes encoding inhibitors of coagulation and their application in early miscarriage aetiology

Properly functioning coagulation in gravidity is not necessary only to provide the continuity of circulation in placenta. Today we recognize that proteins and cells of haemostasis in the maternal blood cooperate with the components of a coagulation cascade produced by embryonic trophoblast cells. Such coordination on the embryomaternal interface is necessary for an intact embryogenesis. Other findings discuss the ability of coagulation components to act also outside the hemocoagulation process, especially as signal molecules, regulators of immune reactions, cell proliferation and others. Haemostasis is thus a complex system and we still do not know all of its pathways. This is perhaps also the reason that in the case of known procoagulant mutations (FV Leiden, gene mutation for prothrombine G20210A) we cannot explain why some carriers suffer recurrent miscarriages and others have uncomplicated pregnancies. The expert community believes that the phenotype manifestation of these mutations in terms of pregnancy losses could be connected to the simultaneous presence (synergistic effect) of other polymorphisms of gene-encoding proteins of haemostasis or the lack thereof (antagonistic effect) (Ref. 59).

The first case report of sulfonylurea use in a woman with permanent neonatal diabetes mellitus due to KCNJ11 mutation during a high-risk pregnancy

Sulfonylureas (SUs) were proven to be more effective than insulin in most Kir6.2 permanent neonatal diabetes mellitus (PNDM) patients. We report SU use during pregnancy in PNDM. A woman with the R201H Kir6.2 mutation became pregnant at the age of 37. The patient had been on glipizide 30 mg for 3 yr; her glycosylated hemoglobin level was 5.8%. She was diagnosed with chronic diabetes complications and a congenital defect of the urogenitary tract-a bicornuate uterus with septum. Because the effect of SU on fetal development is uncertain, she was switched to insulin after the pregnancy diagnosis; however, the subsequent glycemic control was unsatisfactory, with episodes of hyper- and hypoglycemia. Thus, in the second trimester, the patient was transferred to SU (glibenclamide, 40 mg), which resulted in stabilization of glycemic control; glycosylated hemoglobin in the third trimester was 5.8%. Prenatal genetic testing excluded the Kir6.2 R201H mutation in the fetus. A preterm cesarean delivery was carried out in the 35th week. The Apgar score of the newborn boy (weight, 3010 g; 75th percentile) was 8 at 1 min. He presented with hypoglycemia, transient tachypnea of the newborn, and hyperbilirubinemia. The recovery was uneventful. No birth defects were recorded. His development at the ninth month of life was normal. In summary, we show a high-risk pregnancy in long-term PNDM that despite perinatal complications ended with the birth of a healthy child. SUs, which seem to constitute an alternative to insulin during pregnancy in Kir6.2-related PNDM, were used during the conception period and most of the second and third trimesters.

[Association between HLA-DQA1, HLA-DQB1 alleles and risk of early pregnancy loss]

AIM

The aim of the study is to identify HLA-DQA1, HLA-DQB1 allele and to assess the risk of early pregnancy loss of women, couples with reproductive failure in the first trimester of pregnancy in comparison with fertile women, couples. The study group (B) enrolled 61 couples with reproductive failure and the control group (C) enrolled 20 fertile couples with at least 2 children.

METHOD

HLA-DQA1 gene typing was performed using PCR-sequence-specific primer (SSP) on the high resolution level according to established procedure of labeling and using the detection kit (FASTYPE DQASSP Typing, FASTYPE DQA "High Resolution" Typing Sheet) purchased from Bio-Synthesis (USA).

RESULTS

In female patient the highest risk quotient was associated with alleles HLA-DQA 01101/0105 OR 7.19 (95% CI 1.18-5.23; p=0.03) and HLA-DQB5 OR 3.67 (95% CI=1.11-12.0; p=0.037). The lowest but statistically significant risk of pregnancy failure in this group was related to allele HLA-DQB6 OR 0.48 (95% CI=0.22-1.04; p=0.087). In patient and control couples the significantly increased risk of pregnancy failure was related to the frequency of HLA-DQB5 allele OR 2.3 (95% CI 1.09-4.82; p=0,035). The lowest risk quotient in the patient couples was associated with HLA-DQ 0302/0303 allele OR 0.44 (95% CI 0.14-1.36; p=ns).

SUMMARY

HLA-DQA and HLA-DQB allele might influence pregnancy outcome in the Polish population, but further studies are necessary in this regard.

By how much does increased nuchal translucency increase the risk of adverse pregnancy outcome in chromosomally normal fetuses? A study of 16,260 fetuses derived from an unselected pregnant population

OBJECTIVE

In this study we aimed to estimate the magnitude of a possible increase in risk of adverse outcome in fetuses with normal karyotype and increased nuchal translucency (NT), and to determine how well NT measurements can distinguish between fetuses with normal and adverse outcome.

METHODS

We studied 16,260 consecutive fetuses with normal karyotype derived from an unselected pregnant population. The following cut-offs for increased risk of adverse outcome were chosen a priori: NT > or = 95th percentile, > or = 3 mm, > or = 3.5 mm, and > or = 4.5 mm. The positive and negative likelihood ratios (+LR, - LR) of the risk cut-offs with regard to fetal malformation, miscarriage, perinatal death, termination of pregnancy and total adverse outcome were calculated, and receiver-operating characteristics (ROC) curves were drawn.

RESULTS

The total rate of adverse outcome was 2.7%. + LR and - LR of NT > or = 3.0 mm were: for lethal or severe malformation, + LR 15.0 (95% CI 7.0-28.6), - LR 0.89 (95% CI 0.81-0.95); for malformation of at least intermediate severity, + LR 8.1 (95% CI 4.3-14.0), - LR 0.95 (95% CI 0.92-0.97); for termination of pregnancy, + LR 41.6 (95% CI 17.1-86.6), - LR 0.67 (95% CI 0.41-0.85); for any adverse outcome, + LR 6.4 (95% CI 3.4-11), - LR 0.96 (95% CI 0.94-0.98). The odds for these adverse outcomes increased with increasing NT. NT > or = 3 mm did not significantly increase the risk of miscarriage or perinatal death. Areas under ROC curves for NT were small, with 95% CI below or only slightly above 0.5.

CONCLUSION

Our likelihood ratios can be used to calculate the individual risk of unfavorable outcome, but NT screening cannot reliably distinguish between normal and adverse outcome in fetuses with normal karyotype.

The role of thrombofilia related to Factor V Leiden and Factor II G20210A mutations in recurrent abortions

OBJECTIVE

To study, the impact of thrombophilia caused by Factor V, Factor ll G20210A mutations on recurrent abortions, the prevelance of Factor V Leiden and Factor II G20210A mutation in patients with habitual abortions.

METHODS

Forty one patients with a diagnosis of habitual abortion were enrolled in the study. Control group consisted of 50 women without a history of poor obstetric outcome. 10 ml. peripheral venous blood was taken from study and control groups and transferred to EDTA tubes, and were tested for Factor V Leiden and Factor II G20210A mutations by PCR in genetics laboratory.

RESULTS

Phenotypes of 91 cases were determined by PCR for Factor V Leiden. It was established that of 41 patients in the study group, 31 (75.6%) had GG genotype, 9 (22%) had GA genotype and 1 (2.4%) had AA genotype. In the control group, 45 (90%) of 50 women had GG genotype and 5 (10%) had GA genotype. A allele carrier status was found to be 24.4% in study group and 10% in the control group. The difference between them was not statistically significant (p = 0.06).

CONCLUSIONS

The results obtained from patients and control group have no difference in Factor V Leiden and Factor II G20210A mutations.These results suggest that mutations have no role in etiology of 1. and 2. trimester recurrent abortions.

Maternal triglyceride levels and newborn weight in pregnant women with normal glucose tolerance

OBJECTIVE

To determine the predictive value of serum triglyceride levels (TG) for neonatal weight in pregnant women with positive diabetic screening but normal glucose tolerance.

RESEARCH DESIGN AND METHODS

We enrolled 180 pregnant Caucasian women with positive diabetic screening. All women underwent a 3-h 100-g oral glucose tolerance test (OGTT) at 27th +/- 4 week of gestation. At the time of OGTT, we measured: fasting plasma glucose, fasting lipids profile and determined ApoE polymorphisms to evaluate the effects on lipid levels. In 83 women with normal glucose tolerance and at term delivery we evaluated the association between maternal serum TG, specific maternal parameters known to affect fetal growth and newborn weight.

RESULTS

Based on OGTT, gestational diabetes mellitus (GDM) was diagnosed in 36 women (20%), impaired glucose tolerance (IGT) in 23 (13%), and normal glucose tolerance (NGT) in 121 (67%). Serum TG concentration was significantly higher in women with GDM (2.47 +/- 0.77 mmol/l) as compared with NGT (1.99 +/- 0.64 mmol/l) or IGT (1.98 +/- 0.81 mmol/l) (P < 0.01). ApoE3 allelic frequency was 86%, ApoE2 and ApoE4 were 5 and 9%, respectively. We found no clear-cut association between apoE genotype and serum TG concentration. Macrosomia and LGA newborns were more frequent in IGT than in GDM or NGT (P < 0.01). In the 83 women with positive diabetic screening but normal glucose tolerance who delivered at term, the incidence of LGA infants was significantly higher in those with TG levels higher than the 75th percentile (> 2.30 mmol/l) (21%) than in mothers who had normal TG levels (4.5%) (P < 0.05). Pre-pregnancy BMI (r(2) = 0.067), weight gain during pregnancy (r(2) = 0.062), fasting serum TG (r(2) = 0.09), and 2-h post-OGTT glucose levels (r(2) = 0.044) were all associated with neonatal body weight (all P < 0.05 or less). However, on a multiple regression analysis, only pre-pregnancy BMI (F-test = 7.26, P < 0.01), and fasting serum TG (F-test = 4.07, P < 0.01) were independently associated with birth weight.

CONCLUSIONS

Pre-pregnancy BMI and fasting maternal serum TG determined in the last trimester of gestation were independently associated with neonatal birth weight in women with normal glucose tolerance, but positive screening test. TG levels measured in the third trimester of pregnancy are independent of the genetic polymorphism of ApoE.

Diagnosis and therapy of intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is characterized by the occurrence of pruritus mostly in the third trimenon. Diagnosis is based on the presence of pruritus and elevated levels of serum bile acids in the absence of pruritic skin diseases. There is strong evidence of a genetic predisposition for ICP. Numerous studies have investigated the association of known cholestasis genes such as ABCB4 (also designated MDR3), ABCB11 ( BSEP) and ATP8B1 ( FIC1) with ICP. The results of these studies implicate a heterogeneous etiology of this syndrome. ICP increases the risk of preterm delivery and fetal loss. Furthermore, intense pruritus may necessitate premature induction of labor with its known higher frequency of complications for mother and child. Therefore, ICP pregnancies should be managed as high-risk pregnancies. Pharmaceuticals to alleviate pruritus or improve cholestasis like antihistamines, phenobarbital, anion exchange resins, dexamethasone or S-adenosylmethionine are not widely accepted because of questionable efficacy or side effects. Recent randomized studies have shown beneficial effects of ursodeoxycholic acid (UDCA) on laboratory data and pruritus in patients with ICP. Improved knowledge about the diagnostic classification of different types and pathophysiological mechanisms of ICP may allow for a more targeted treatment of this disease in future.

Advances in preconception genetic counseling

Preconception counseling offers couples contemplating pregnancy the opportunity to identify and reduce potential pregnancy risks, plan care for known risks, and establish early prenatal care. The goal of preconception counseling is to promote physically and emotionally healthy parents in an attempt to ensure optimal prenatal, intrapartum, and postpartum maternal and fetal health. The advantages of addressing these issues prior to conception include the opportunity of giving recurrence or occurrence risk information for informed decision regarding pregnancy, the accessibility of more reproductive options such as preimplantation genetic diagnosis, and the opportunity to make lifestyle, medical, and behavior alterations for optimal maternal and fetal outcome. This article will discuss advances and updates in preconception genetic counseling including risk assessment and potential intervention for concerns identified through evaluation of family history, ethnicity, maternal age, medical and obstetric history, and associated psychosocial and nursing implications. Significant advances have emerged in the areas of cystic fibrosis carrier screening, first trimester screening, preimplantation genetic diagnosis, and detection and treatment of maternal thrombophilia.

Fetal sex determination from maternal blood at 6 weeks of gestation when at risk for 21-hydroxylase deficiency

BACKGROUND

21-hydroxylase deficiency can lead to masculinization of female fetuses. Corticosteroid therapy may reduce these effects. When the fetus is male, this approach means that unnecessary treatment, with theoretic side effects, is given until the result of chorionic villus sampling (CVS), a procedure with known risks, is available.

CASE

A woman was referred for prenatal assessment at 6 weeks' gestation because her first daughter had been born virilized from 21-hydroxylase deficiency. A real-time polymerase chain reaction assay was performed on maternal blood to detect the fetal Y chromosome-associated SRY gene. A positive signal for the SRY gene was observed. The assay was repeated a few days later, and the result was again consistent with a male fetus.

CONCLUSION

Analysis of cell-free fetal deoxyribonucleic acid in maternal plasma for fetal sex determination might reduce the need for corticosteroid administration and CVS in women with fetuses at risk for 21-hydroxylase deficiency.

Chromosomal abnormalities in embryos

Chromosomal analysis was performed on 1620 embryos generated in vitro by patients with a poor prognosis of pregnancy. A diagnosis was yielded in 1596 embryos: 536 (34%) were euploid and 1060 (66%) carried chromosomal abnormalities. The results revealed a strong association between chromosomal abnormalities, cellular stage and percentage of fragmentation. In addition, 92% of embryos with multinucleated cells were diagnosed mosaics, whereas the presence of cytoplasmic concentration was associated to 86% chromosomal abnormalities. The rate of development to expanded blastocysts was dependent on both the cleavage stage at the time of blastomere biopsy and the chromosomal status of the embryos. The highest percentage of blastocyst growth derived from embryos with 7-8 cells on the morning of day 3: 68% were generated from euploid embryos and 43% from chromosomally abnormal embryos. These findings suggest that morphological criteria alone are not sufficient in poor prognosis patients to guarantee the best embryo selection.

[Sickle cell anemia and pregnancy: review of 68 cases in Guadeloupe]

Pregnancy in women with major sickle cell syndromes is a high risk maternofetal situation. This descriptive study presents the features and the clinical course of 68 pregnancies in sickle cell women who were delivered in Guadeloupe from January 1(st) 1993 to December 31(st) 1997. Specific complications were observed in all hemoglobin types, but with a severer course in SS women. Painful vaso-occlusive crises were the main causes of hospitalisation (88% of SS pregnancies and 27% of SC pregnancies) associated most often with worsening anemia and / or infection. Acute chest syndrome was observed in all genotypes at any time throughout pregnancy and during the post partum period. One death occurred (a 16 years old SBeta(+)thal woman). Fetal mortality and morbidity were also high, intrauterine growth retardation and fetal death being the most frequent fetal complications. The rates of prematurity (21%) and caesarean section (48%) were higher than in the whole population. Three (3) neonatal deaths occurred. A multidisciplinary and specific approach, vigilance of health care providers and patient compliance are required to manage efficiently pregnancy, delivery and post partum in sickle cell women.

Screening for Down's syndrome by fetal nuchal translucency measurement in a high-risk population

OBJECTIVE

To examine the discriminative capacity of nuchal translucency measurement in the detection of trisomy 21 and other chromosomal anomalies.

DESIGN

Prospective cohort study.

SUBJECTS

A total of 2247 women with viable singleton pregnancies between 10 and 14 weeks' gestation attending a prenatal diagnosis center for fetal karyotyping.

METHODS

The fetal nuchal translucency was measured transabdominally in all women before invasive prenatal testing.

RESULTS

Chromosomal abnormalities were found in 63 fetuses, including 36 with Down's syndrome. The likelihood of the presence of chromosomal abnormalities increased with larger nuchal translucency thickness. A nuchal translucency of 3 mm or more identified 25 out of 36 fetuses (69%) with trisomy 21 at the expense of a 4.0% false-positive rate. Correction of nuchal translucency measurements for differences due to variation of the measurement with gestational age, either by using the 'delta-value' or multiples of the median (MoM), did not improve the detection rate in our patient data set.

CONCLUSIONS

The discriminative capacity of nuchal translucency measurement makes it a useful tool in screening for trisomy 21 and other chromosomal anomalies.

Incidence of chromosomal abnormalities from a morphologically normal cohort of embryos in poor-prognosis patients

PURPOSE

Preimplantation genetic diagnosis of aneuploidy was performed on the embryos yielded by 70 poor-prognosis patients, with the aim of transferring those with a normal chromosomal complement, thus possibly increasing the chances of pregnancy.

METHODS

Multicolor fluorescence in situ hybridization (FISH) was applied for the simultaneous detection of chromosomes X, Y, 13, 16, 18, and 21. Inclusion criteria were (1) a maternal age of 36 years or older (n = 33), (2) three or more previous in vitro fertilization cycles (n = 20), and (3) an altered karyotype (n = 17).

RESULTS

A total of 412 embryos underwent FISH, resulting in 234 (57%) that were chromosomally abnormal. Euploid embryos were available for transfer in 59 patients, generating 19 pregnancies (32%), with an implantation rate of 19.9%.

CONCLUSIONS

High rates of chromosomally abnormal embryos in poor-prognosis patients can determine repeated in vitro fertilization failures when embryo selection is performed on the basis of morphological criteria alone. Hence, the FISH analysis could represent the prevailing approach for the identification of embryos possessing full potential for developing to term.

Prenatal determination of genotypes Kell and Cellano in at-risk pregnancies

OBJECTIVE

To evaluate the accuracy of a DNA-based testing methodology in determining the KEL1 and KEL2 (Kell and Cellano) genotype of fetuses at risk for Kell or Cellano hemolytic disease.

STUDY DESIGN

DNA was extracted from chorionic villus samples (CVS) or amniotic fluid (AF) cells, a portion of the Kell gene was amplified, the amplified product was cut with a restriction enzyme that recognizes the KEL1 nucleotide substitution, and the digested product was run on a polyacrylamide gel to separate the fragments. This analysis was routinely run on uncultured cells to provide rapid results. Testing of parental DNA was performed in conjunction with fetal analysis to ensure that their alleles were detectable with this DNA test.

RESULTS

We determined the fetal KEL1 and KEL2 genotype in 1 CVS and 65 AF specimens. Forty-eight of them were determined to be KEL2, 17 were KEL1/2, and 1 was KEL1. Among the fetuses born to date, follow-up information was available on 14 of them, 11 KEL2 and 3 KEL1/2. In all 14 there was complete correlation between the DNA analysis and the serotype or clinical course.

CONCLUSION

Determination of the fetal KEL1 and KEL2 genotype using this DNA-based method provides accurate and timely information that can aid the prenatal care of women sensitized to these Kell antigens.

Karyotyping of at risk fetuses by cordocentesis in advanced gestation

Fetal blood obtained by cordocentesis was cultured to obtain rapid karyotypes of fetuses at risk during the late second trimester. Ninety nine fetal blood samples were studied for chromosomal abnormalities. The commonest indications for the procedure were abnormalities detected on ultrasonography (47.7%), and previous child with Down syndrome. Analysis of the 67 successful cultures showed four (5.9%) karyotypic abnormalities. The technique proved helpful in the obstetrical management of at risk fetuses.

Nuchal translucency cannot be used as a screening test for chromosomal abnormalities in the first trimester of pregnancy in a routine ultrasound practice

We decided to assess the practicability of introducing nuchal translucency (NT) measurements as a screening programme for fetal Down's syndrome in the first trimester of pregnancy, within the population of women who receive ultrasound examinations in our department. Over a 1-year period, measurements were made in 923 fetuses at < or = 13 weeks' gestation. Fifty-two per cent of the mothers were 36 years or older or had a past history of a chromosomally abnormal fetus or child. Measurements were only successful 58 per cent of the time; this improved to 74 per cent if the fetus was > or = 10 weeks' gestation. Inter-observer variability did not cause a major problem. There were 36 fetuses with an NT > or = 3 mm. Two of these fetuses had a chromosomal abnormality (both trisomy 21). The translucency in these two cases was so large that they would have been detected and offered prenatal diagnosis even prior to this study. There was a total of ten aneuploidies in the study group. Only two of these fetuses were detected by this screening method; five had an NT measurement < 3 mm and in three fetuses (all trisomy 21), measurements were not successful. We outline the practical problems that could be expected by introducing ultrasound screening in a routine setting. Although the efficacy of the test in a research setting may seem good, the effectiveness in everyday usage appears much less impressive, making its uptake as a screening technique in a general ultrasound practice at this stage imprudent.

Preconception care: a means of prevention

Preconceptional health promotion should provide a prevention framework for interactions with all women of childbearing potential. Preconceptional counselling is properly directed by specialists in the field of obstetrics and gynaecology, but a multispecialty effort may be needed to achieve adequate information for decision-making. Preconceptional health care offers an important opportunity for physicians involved in women's health to expand a primary care and a primary prevention focus. The obstetrician or gynaecologist is not only involved in acute diagnosis and treatment plans but also in disease prevention, risk and behaviour modification and counselling, which are integral parts of primary prevention and co-ordinated women's health care.

Framing the debate: can prenatal care help to reduce the black-white disparity in infant mortality?

Prenatal care has been identified as necessary to reducing the disparity in infant mortality between black and white infants. The purpose of this paper is to review determinants of the disparity and describe the contribution that prenatal care can make to modifying those determinants, biologic or social. When examined by birthweight categories, 25% of the disparity is due to excess deaths among normal birthweight infants (> or = 2500 g); 13% is due to excess deaths among moderate low birthweight infants (1500-2499g); and 62% of the disparity is due to excess deaths among very low birthweight infants. Normal birthweight black infants have higher rates of death due to infections, injuries, and sudden infant death syndrome. Very low birthweight black infants account for the increasing disparity in infant mortality. Social determinants of the disparity in infant mortality include the effects of poverty and the accompanying problems of limited access to health care services, preventive care, and good nutrition. Prenatal care may reduce the disparity by using both high-risk and population-based prevention strategies. This combination of strategies would identify and treat medically high-risk women before delivery and provide preventive care to all women, regardless of their risk status. Although both strategies have a potential for producing modest reductions, neither has proved to be effective.

The role of the genetic counselor in a perinatal unit

Perinatal units are becoming increasingly aware of the importance of a genetic counselor in a multidisciplinary team. As such, genetic counselors have the opportunity to contribute to the complex and labor-intensive care of high-risk patients in the perinatal setting. Their role is ever changing to fit this evolving and growing field which, although often difficult and challenging, can also be very rewarding.