Modified multiple marker aneuploidy screening as a primary screening test for preeclampsia.

BACKGROUND: Abnormal levels of maternal biochemical markers used in multiple marker aneuploidy screening have been associated with adverse pregnancy outcomes. This study aims to assess if a combination of maternal characteristics and biochemical markers in the first and second trimesters can be used to screen for preeclampsia (PE). The secondary aim was to assess this combination in identifying pregnancies at risk for gestational hypertension and preterm birth. METHODS: This case-control study used information on maternal characteristics and residual blood samples from pregnant women who have undergone multiple marker aneuploidy screening. The median multiple of the median (MoM) of first and second trimester biochemical markers in cases (women with PE, gestational hypertension and preterm birth) and controls were compared. Biochemical markers included pregnancy-associated plasma protein A (PAPP-A), placental growth factor (PlGF), human chorionic gonadotropin (hCG), alpha feto-protein (AFP), unconjugated estriol (uE3) and Inhibin A. Logistic regression analysis was used to estimate screening performance using different marker combinations. Screening performance was defined as detection rate (DR) and false positive rate (FPR). Preterm and early-onset preeclampsia PE were defined as women with PE who delivered at < 37 and < 34 weeks of gestation, respectively. RESULTS: There were 147 pregnancies with PE (81 term, 49 preterm and 17 early-onset), 295 with gestational hypertension, and 166 preterm birth. Compared to controls, PE cases had significantly lower median MoM of PAPP-A (0.77 vs 1.10, p < 0.0001), PlGF (0.76 vs 1.01, p < 0.0001) and free-ß hCG (0.81 vs. 0.98, p < 0.001) in the first trimester along with PAPP-A (0.82 vs 0.99, p < 0.01) and PlGF (0.75 vs 1.02, p < 0.0001) in the second trimester. The lowest first trimester PAPP-A, PlGF and free ß-hCG were seen in those with preterm and early-onset PE. At a 20% FPR, 67% of preterm and 76% of early-onset PE cases can be predicted using a combination of maternal characteristics with PAPP-A and PlGF in the first trimester. The corresponding DR was 58% for gestational hypertension and 36% for preterm birth cases. CONCLUSIONS: Maternal characteristics with first trimester PAPP-A and PlGF measured for aneuploidy screening provided reasonable accuracy in identifying women at risk of developing early onset PE, allowing triage of high-risk women for further investigation and risk-reducing therapy. This combination was less accurate in predicting women who have gestational hypertension or preterm birth.

Prenatal screening for trisomy 21: a comparative performance and cost analysis of different screening strategies.

BACKGROUND: Prenatal screening for chromosome aneuploidies have constantly been evolving, especially with the introduction of cell-free fetal DNA (cfDNA) screening in the most recent years. This study compares the performance, costs and timing of test results of three cfDNA screening implementation strategies: contingent, reflex and primary. METHODS: We modelled enhanced first trimester screening (eFTS) as the first-tier test in contingent or reflex strategies. cfDNA test was performed contingent on or reflex from eFTS results. A comparison was made between cfDNA screening using sequencing technology and Rolling Circle Amplification (RCA)/imaging solution. All model assumptions were based on results from previous publications or information from the Ontario prenatal screening population. RESULTS: At an eFTS risk cut-off of ≥1/1000, contingent and reflex cfDNA screening have the same detection rate (DR) (94%) for trisomy 21. Reflex cfDNA screening using RCA/Imaging solution provided the lowest false positive rate and cost. The number of women requiring genetic counselling and diagnostic testing was significantly reduced and women received their cfDNA screening result 9 days sooner compared with the contingent model. While primary cfDNA screening improved the trisomy 21 DR by 3-5%, it was more costly and more women required diagnostic testing. CONCLUSION: Reflex cfDNA screening is the most cost-effective prenatal screening strategy. It can improve the efficiency of prenatal aneuploidy screening by reducing the number of patient visits and providing more timely results.

Prenatal screening for preeclampsia: the roles of placental growth factor and pregnancy-associated plasma protein A in the first trimester and placental growth factor and soluble fms-like tyrosine kinase 1-placental growth factor ratio in the early second trimester.

BACKGROUND: Professional societies have recommended universal first trimester screening for preeclampsia and a second or third trimester soluble fms-like tyrosine kinase-1-placental growth factor ratio test to assess for preeclampsia and its severity. However, it may not be feasible to implement the most optimal screening protocol for preeclampsia in the first trimester which uses a combination of maternal characteristics, maternal biophysical and biochemical markers due to limitations in the access to uterine artery doppler ultrasound. There are inconsistent findings on how early in the second trimester the fms-like tyrosine kinase-1-placental growth factor ratio begins to provide useful information in preeclampsia prediction. OBJECTIVE: This study aimed to assess the accuracy of (1) a combination of maternal characteristics, maternal serum pregnancy-associated plasma protein A, and placental growth factor in the screening for preeclampsia in the first trimester; and (2) placental growth factor or soluble fms-like tyrosine kinase-1-placental growth factor ratio in the prediction of preeclampsia in the early second trimester. STUDY DESIGN: This retrospective case-control study used frozen residual blood samples from women who had aneuploidy screening and delivered at a tertiary center. The case group included pregnancies with gestational hypertension or preeclampsia (further classified as early-onset [birth at <34 weeks' gestation] and preterm preeclampsia [birth at <37 weeks' gestation]). Each case was matched with 3 control pregnancies by date of blood sample draw, gestational age at first blood sample draw, maternal age, maternal ethnicity, type of multiple-marker screening, and amount of residual sample. Mann-Whitney U tests were used to assess the associations between serum markers and the risk of preeclampsia. Logistic regressions were used to assess if the risk of preeclampsia can be predicted using a combination of maternal characteristics and serum markers. RESULTS: The case group included 146 preeclampsia and 295 gestational hypertension cases. Compared with the controls, preeclampsia cases had significantly lower first-trimester pregnancy-associated plasma protein A and placental growth factor. At a 20% false-positive rate, 71% of early-onset and 58% of preterm preeclampsia cases can be predicted using maternal characteristics, pregnancy-associated plasma protein A, and placental growth factor. Preeclampsia cases had lower second-trimester placental growth factor and a higher soluble fms-like tyrosine kinase-1-placental growth factor ratio. At a 10% false-positive rate, 80% and 53% of early-onset preeclampsia can be predicted using maternal characteristics and placental growth factor or soluble fms-like tyrosine kinase-1-placental growth factor ratio, respectively. CONCLUSION: The current first-trimester aneuploidy screening programs may be expanded to identify women at increased risk of developing preeclampsia. Early in the second trimester, placental growth factor alone provided better prediction for preeclampsia compared with the soluble fms-like tyrosine kinase-1-placental growth factor ratio.

Further support of the role of CYP1B1 in patients with Peters anomaly.

PURPOSE: Peters anomaly is a developmental anomaly of the eye frequently associated with glaucoma. The aim of this study was to further define the molecular basis of this condition. METHODS: The role of four candidate genes implicated in ocular development or glaucoma, PAX6, PITX2, MYOC, and CYP1B1, was studied in 15 patients with Peters anomaly. Mutational analysis used a combination of single strand conformation polymorphism (SSCP) and direct cycle sequencing. RESULTS: Four mutations in CYP1B1 were found in 3/15 (20%) affected individuals compared with 1/140 (0.7%) control individuals. CONCLUSIONS: This study supports the role of CYP1B1 as a causative gene in Peters anomaly. Furthermore, this emphasizes the broad range of phenotypic expression for CYP1B1 mutations, and its role in eye development.

CRYBB1 mutation associated with congenital cataract and microcornea.

PURPOSE: The molecular characterization of a UK family with an autosomal dominant congenital cataract associated with microcornea is reported. METHODS: Family history and clinical data were recorded. This phenotype was linked to a 7.6 cM region of chromosome 22q11.2-q12.2, spanning the beta-crystallin gene cluster (ZMax of 3.91 for marker D22S1114 at theta=0). Candidate genes were PCR amplified and screened for mutations on both strands using direct sequencing. RESULTS: Sequencing of the coding regions and flanking intronic sequences of CRYBB2 and CRYBB1 showed the presence of a novel, heterozygous X253R change in exon 6 of CRYBB1. SSCP analysis confirmed that this sequence change segregated with the disease phenotype in all available family members and was not found in 109 ethnically matched controls. CONCLUSIONS: X253R is predicted to elongate the COOH-terminal extension of the protein and would be expected to disrupt beta-crystallin interactions. This is the first documented involvement of CRYBB1 in ocular development beyond cataractogenesis.

Digenic inheritance of early-onset glaucoma: CYP1B1, a potential modifier gene.

"Early-onset glaucoma" refers to genetically heterogeneous conditions for which glaucoma manifests at age 5-40 years and for which only a small subset is molecularly characterized. We studied the role of MYOC, CYP1B1, and PITX2 in a population (n=60) affected with juvenile or early-onset glaucoma from the greater Toronto area. By a combination of single-strand conformation polymorphism and direct cycle sequencing, MYOC mutations were detected in 8 (13.3%) of the 60 individuals, CYP1B1 mutations were detected in 3 (5%) of the 60 individuals, and no PITX2 mutations were detected. The range of phenotypic expression associated with MYOC and CYP1B1 mutations was greater than expected. MYOC mutations included cases of juvenile glaucoma with or without pigmentary glaucoma and mixed-mechanism glaucoma. CYP1B1 mutations involved cases of juvenile open-angle glaucoma, as well as cases of congenital glaucoma. The study of a family with autosomal dominant glaucoma showed the segregation of both MYOC and CYP1B1 mutations with disease; however, in this family, the mean age at onset of carriers of the MYOC mutation alone was 51 years (range 48-64 years), whereas carriers of both the MYOC and CYP1B1 mutations had an average age at onset of 27 years (range 23-38 years) (P=.001). This work emphasizes the genetic heterogeneity of juvenile glaucoma and suggests, for the first time, that (1) congenital glaucoma and juvenile glaucoma are allelic variants and (2) the spectrum of expression of MYOC and CYP1B1 mutations is greater than expected. We also propose that CYP1B1 may act as a modifier of MYOC expression and that these two genes may interact through a common pathway.

VSX1: a gene for posterior polymorphous dystrophy and keratoconus.

We identified mutations in the VSX1 homeobox gene for two distinct inherited corneal dystrophies; posterior polymorphous dystrophy (PPD) and keratoconus. One of the mutation (R166W) responsible for keratoconus altered the homeodomain and impaired DNA binding. Two other sequence changes (L159M and G160D) were associated with keratoconus and PPD, respectively, and involved a region adjacent to the homeodomain. The G160D substitution, and a fourth defect affecting the highly conserved CVC domain (P247R), occurred in a child with very severe PPD who required a corneal transplant at 3 months of age. In this family, relatives with the G160D change alone had mild to moderate PPD, while P247R alone caused no corneal abnormalities. However, with either the G160D or P247R mutation, electroretinography detected abnormal function of the inner retina, where VSX1 is expressed. These data define the molecular basis of two important corneal dystrophies and reveal the importance of the CVC domain in the human retina.