Pregnancy outcome and prenatal diagnosis of sex chromosome abnormalities in Hawaii, 1986-1999

Advances in genomic diagnosis of a large cohort of Egyptian patients with disorders of sex development

Disorders/differences of sex development (DSD) comprise a group of congenital disorders that affect the genitourinary tract and usually involve the endocrine and reproductive system. The aim of this work was to identify genetic variants responsible for disorders of human urogenital development in a cohort of Egyptian patients. This three-year study included 225 patients with various DSD forms, referred to the genetic DSD and endocrinology clinic, National Research Centre, Egypt. The patients underwent thorough clinical examination, hormonal and imaging studies, detailed cytogenetic and fluorescence in situ hybridization analysis, and molecular sequencing of genes known to commonly cause DSD including AR, SRD5A2, 17BHSD3, NR5A1, SRY, and WT1. Whole exome sequencing (WES) was carried out for 18 selected patients. The study revealed a high rate of sex chromosomal DSD (33%) with a wide array of cytogenetic abnormalities. Sanger sequencing identified pathogenic variants in 33.7% of 46,XY patients, while the detection rate of WES reached 66.7%. Our patients showed a different mutational profile compared with that reported in other populations with a predominance of heritable DSD causes. WES identified rare and novel pathogenic variants in NR5A1, WT1, HHAT, CYP19A1, AMH, AMHR2, and FANCA and in the X-linked genes ARX and KDM6A. In addition, digenic inheritance was observed in two of our patients and was suggested to be a cause of the phenotypic variability observed in DSD.

The outcome of prenatal identification of sex chromosome abnormalities

OBJECTIVE

The outcome of a pregnancy following identification of a sex chromosome abnormality (SCA) is unclear. The aims of this study were to ascertain the prevalence of SCA detected prenatally in Scotland and to determine the outcomes for these cases.

DESIGN

Following retrospective identification of all prenatal karyotypes performed in Scotland between 2000 and 2012, data linkage was performed to obtain information regarding maternal characteristics and pregnancy outcomes. Detailed outcome data were also collected for all affected offspring in the West of Scotland and Grampian regions within Scotland.

RESULTS

Of the 28 145 pregnancies that had a karyotype over the study period, records were available for 27 152 (96%). Karyotype abnormalities were identified in 2139 (8%), with SCA being identified in 321(1%) tests. 45,X was identified as the commonest SCA in 135 pregnancies. Of 121 pregnancies with SCA in the West of Scotland and Grampian, 64 (53%), 52 (43%) and 5 (4%) led to a live birth, termination and intrauterine death, respectively. Of the 64 live births, 21 (33%) had a postnatal karyotype and 35 (54%) received specialist follow-up for the SCA that was identified prenatally.

CONCLUSIONS

Abnormalities of sex chromosomes are identified in approximately 1% of all pregnancies that undergo a prenatal karyotype. There is a need to review the prenatal as well as postnatal care of the affected mother and offspring.

Parental decisions following prenatal diagnosis of chromosomal abnormalities: implications for genetic counseling practice in Japan

Parental decision-making to terminate or continue a pregnancy was studied after prenatal diagnosis of a chromosome aneuploidy among a sample of patients around the city of Nagoya, Japan. A total of 1,051 amniocentesis cases at 15-18 weeks of gestation were analyzed. Of these, 60 cases of chromosomal anomalies with aneuploidies were diagnosed by conventional cytogenetic analysis. Of the 45 diagnoses of autosomal chromosome aneuploidies, pregnancy was terminated in 93.3 % of the cases. Of the 15 cases diagnosed with sex chromosome aneuploidy, pregnancy was terminated in 46.7 %. Differences in parental decisions with respect to maternal age, gestational week at diagnosis, number of pregnancies per individual and existing number of children were not significant in patients diagnosed either with autosomal or sex chromosome aneuploidy. The findings indicate that when diagnosed with a chromosome aneuploidy in which a severe prognosis was expected, most couples decided to terminate the pregnancy in Japan. Implications of these findings for expanding the profession of genetic counseling are discussed and research recommendations are provided.

Assessment of fetal sex chromosome aneuploidy using directed cell-free DNA analysis

OBJECTIVE

To examine the performance of chromosome-selective sequencing of cell-free (cf) DNA in maternal blood for assessment of fetal sex chromosome aneuploidies.

METHODS

This was a case-control study of 177 stored maternal plasma samples, obtained before fetal karyotyping at 11-13 weeks of gestation, from 59 singleton pregnancies with fetal sex chromosome aneuploidies (45,X, n = 49; 47,XXX, n = 6; 47,XXY, n = 1; 47,XYY, n = 3) and 118 with euploid fetuses (46,XY, n = 59; 46,XX, n = 59). Digital analysis of selected regions (DANSR™) on chromosomes 21, 18, 13, X and Y was performed and the fetal-fraction optimized risk of trisomy evaluation (FORTE™) algorithm was used to estimate the risk for non-disomic genotypes. Performance was calculated at a risk cut-off of 1:100.

RESULTS

Analysis of cfDNA provided risk scores for 172 (97.2%) samples; 4 samples (45,X, n = 2; 46,XY, n = 1; 46,XX, n = 1) had an insufficient fetal cfDNA fraction for reliable testing and 1 case (47,XXX) failed laboratory quality control metrics. The classification was correct in 43 (91.5%) of 47 cases of 45,X, all 5 of 47,XXX, 1 of 47,XXY and 3 of 47,XYY. There were no false-positive results for monosomy X.

DISCUSSION

Analysis of cfDNA by chromosome-selective sequencing can correctly classify fetal sex chromosome aneuploidy with reasonably high sensitivity.

Decision to abort after a prenatal diagnosis of sex chromosome abnormality: a systematic review of the literature

We performed a systematic review of factors affecting parental decisions to continue or terminate a pregnancy after prenatal diagnosis of a sex chromosome abnormality, as reported in published studies from 1987 to May 2011. Based on the Matrix Method for systematic reviews, 19 studies were found in five electronic databases, meeting specific inclusion/exclusion criteria. Abstracted data were organized in a matrix. Alongside the search for factors influencing parental decisions, each study was judged on its methodological quality and assigned a methodological quality score. Decisions either to terminate or to continue a sex chromosome abnormality-affected pregnancy shared five similar factors: specific type of sex chromosome abnormality, gestational week at diagnosis, parents' age, providers' genetic expertise, and number of children/desire for (more) children. Factors unique to termination decisions included parents' fear/anxiety and directive counseling. Factors uniquely associated with continuation decisions were parents' socioeconomic status and ethnicity. The studies' average methodological quality score was 10.6 (SD = 1.67; range, 8-14). Findings from this review can be useful in adapting and modifying guidelines for genetic counseling after prenatal diagnosis of a sex chromosome abnormality. Moreover, improving the quality of future studies on this topic may allow clearer understanding of the most influential factors affecting parental decisions.

Counselling of a couple faced with a prenatal diagnosis of Klinefelter syndrome

When a prenatal diagnosis of Klinefelter syndrome (KS) is made, a couple is faced with an unfamiliar and unexpected diagnosis. The aim of this article is to give clues to prenatal counselling in this situation. The information provided to couples facing a prenatal diagnosis of KS should ideally be based on longitudinal studies of unselected individuals, including those diagnosed prenatally. Indeed, there are several reasons to think that the phenotype of individuals diagnosed prenatally is globally less severe than in those diagnosed postnatally. Based on these studies, the evidence to be explained to couples to help them make an informed decision about the pregnancy is the following: except for rather tall height, generally normal appearance throughout life; increased risk of learning disabilities; spontaneous puberty, reduced testicular size, usual need for testosterone supplementation from adolescence onward; increased risk of gynecomastia; sexual orientation similar to the general male population; infertility, but with the possibility of having biological offspring with assisted reproductive techniques. In this article, we review the evidence about the phenotype of KS according to the circumstances of diagnosis and its use in counselling couples faced with a prenatal diagnosis of this common condition.

CONCLUSION

Cohort studies including individuals with KS diagnosed prenatally are still lacking.

Sex chromosome trisomies in Europe: prevalence, prenatal detection and outcome of pregnancy

This study aims to assess prevalence and pregnancy outcome for sex chromosome trisomies (SCTs) diagnosed prenatally or in the first year of life. Data held by the European Surveillance of Congenital Anomalies (EUROCAT) database on SCT cases delivered 2000-2005 from 19 population-based registries in 11 European countries covering 2.5 million births were analysed. Cases included were livebirths diagnosed to 1 year of age, fetal deaths from 20 weeks gestation and terminations of pregnancy for fetal anomaly (TOPFA). In all, 465 cases of SCT were diagnosed between 2000 and 2005, a prevalence of 1.88 per 10,000 births (95% CI 1.71-2.06). Prevalence of XXX, XXY and XYY were 0.54 (95% CI 0.46-0.64), 1.04 (95% CI 0.92-1.17) and 0.30 (95% CI 0.24-0.38), respectively. In all, 415 (89%) were prenatally diagnosed and 151 (36%) of these resulted in TOPFA. There was wide country variation in prevalence (0.19-5.36 per 1000), proportion prenatally diagnosed (50-100%) and proportion of prenatally diagnosed resulting in TOPFA (13-67%). Prevalence of prenatally diagnosed cases was higher in countries with high prenatal detection rates of Down syndrome. The EUROCAT prevalence rate for SCTs diagnosed prenatally or up to 1 year of age represents 12% of the prevalence expected from cytogenetic studies of newborn babies, as the majority of cases are never diagnosed or are diagnosed later in life. There is a wide variation between European countries in prevalence, prenatal detection and TOPFA proportions, related to differences in screening policies as well as organizational and cultural factors.

Triple X syndrome: a review of the literature

The developmental and clinical aspects in the literature on triple X syndrome are reviewed. Prenatal diagnosis depends on karyotyping. The incidence is 1 of 1000 females. At birth, 47,XXX girls have a lower mean birth weight and a smaller head circumference. Triple X diagnosis was not suspected at birth. The maternal age seems to be increased. Toddlers with triple X syndrome show delayed language development. The youngest girls show accelerated growth until puberty. EEG abnormalities seem to be rather common. Many girls show motor-coordination problems and auditory-processing disorders are not rare. Scoliosis is probably more common in adolescent cases. The IQ levels are 20 points below that of controls, and verbal IQ is lowest. The girls struggle with low self-esteem and they need psychological, behavioural and educational support. They perform best in stable families. After leaving school they seem to feel better. In adults, premature ovarian failure seems to be more prevalent than in controls. MRIs of the brain seem to show decreased brain volumes. The 47,XXX women most often find jobs that reflect their performance abilities. Psychotic illness seems to be more prevalent in triple X adult women than in controls. Psychotic disorders respond well to psychotropic drugs. Triple X adults suffer more frequently from cyclothymic and labile personality traits. Research on triple X syndrome may yield more insight into brain and behaviour relations, developmental psychopathology, auditory-processing disorders, EEG disorders, personality and psychotic disorders, etc.

Outcome of chromosomally abnormal pregnancies in Lebanon: obstetricians' roles during and after prenatal diagnosis

OBJECTIVES

To better understand obstetrician experiences in Lebanon when disclosing abnormal amniocentesis results.

METHODS

Structured interviews with 38 obstetricians identified as caregivers from the American University of Beirut Medical Center Cytogenetics Laboratory database of patients with abnormal amniocentesis results between 1999 and 2005.

RESULTS

Obstetricians were primarily male, Christian, and with an average of 14 years of experience. They reported doing most pre-amniocentesis counseling, including discussion of risk for common autosomal aneuplodies (95%), and procedure-related risk (95%). Obstetricians reported that 80% of patients at risk for aneuploidy underwent amniocentesis. The study population reported on 143 abnormal test results (124 autosomal abnormalities). When disclosing results, obstetricians reportedly discussed primarily physical and cognitive features of the diagnosis. They varied in levels of directiveness and comfort in providing information. Our records showed that 59% of pregnancies with sex chromosome abnormalities were terminated compared to 90% of those with autosomal aneuploidies; various reasons were proposed by obstetricians.

CONCLUSIONS

This study is among the few to assess prenatal diagnosis practices in the Middle East, with a focus on the role of the obstetrician. Given the influence of culture and social norms on prenatal decision-making, it remains important to understand the various impacts on clinical practice in many nations.

Variation in the decision to terminate pregnancy in the setting of fetal aneuploidy

OBJECTIVE

To investigate the rate of pregnancy termination for various fetal aneuploidies, and to evaluate predictors of this choice.

METHODS

A retrospective cohort study identified all patients with any of seven common fetal aneuploidies (trisomies 21, 18, and 13; 45,X, 47,XXX, 47,XXY, and 47,XYY) at a referral prenatal diagnosis unit from 1983 to 2003. We abstracted type of aneuploidy, time and type of diagnostic procedure, maternal age, and ethnicity as predictors of the decision to terminate. Statistical comparisons were made using the chi-square test. Potential confounding variables were controlled for using multivariate logistic regression.

RESULTS

Overall, there were 833 patients who had fetuses with aneuploidy. In our study population, the overall rate of termination was 81%: 86% in cases of autosomal trisomy and 60% in cases of sex chromosome aneuploidy (SCA) (p < 0.001). Rates were lowest in cases with the least severe prognosis, 47,XYY (57%) and 47,XXX (40%) compared with 45,X (65%) and 47,XXY (70%) (p = 0.05). Patients with SCA detected by chorionic villus sampling (CVS) had a higher termination rate than those who had undergone amniocentesis (77% vs 55%, p = 0.015). Increased maternal age was associated with higher termination rates in autosomal trisomy (88% vs 76% p < 0.001) and a trend toward decreased rates in those with SCA (55% vs 71%, p = 0.06). Hispanic women were less likely to terminate pregnancy (69%, p = 0.01) than those from other racial/ethnic groups.

CONCLUSION

Type and severity of aneuploidy, type of diagnostic procedure, maternal age, and ethnicity contribute to patients' decision-making in the setting of fetal aneuploidy.

Parental decisions following the prenatal diagnosis of sex chromosome abnormalities

OBJECTIVE

To report parental decisions regarding pregnancy termination following the prenatal diagnosis of a sex chromosome abnormality (SCA) in the fetus.

METHODS

Retrospective collection of data from records of 61 families receiving genetic counseling after prenatal diagnosis of a sex chromosome abnormality in the fetus in the Division of Medical Genetics, University Hospital of Geneva during the time period 1980-2001.

RESULTS

Among 61 couples with a prenatal diagnosis of a sex chromosome abnormality (SCA), 44 couples (72.1%) decided to terminate pregnancy. Pregnancy termination rates were 100, 73.9, 70, 50 and 42.9% for Turner syndrome, Klinefelter syndrome, 47,XXX females, 47,XYY males, and mosaic cases, respectively. In all 11 cases with a fetal abnormality seen on ultrasound, pregnancy was terminated. Termination rates were higher among couples with a higher mean number of previous children. Maternal age and year of test did not influence parental decisions.

CONCLUSIONS

Parental decision to terminate a pregnancy for a fetus with a SCA varied by type of sex chromosome abnormality, by presence of fetal ultrasound anomalies, and by the mean number of previous children.