Consanguinity and pregnancy outcomes in a multi-ethnic, metropolitan European population

Professionals' views on providing personalized recurrence risks for de novo mutations: Implications for genetic counseling

When an apparent de novo (new) genetic change has been identified as the cause of a serious genetic condition in a child, many couples would like to know the risk of this happening again in a future pregnancy. Current practice provides families with a population average risk of 1%-2%. However, this figure is not accurate for any specific couple, and yet, they are asked to make decisions about having another child and/or whether to have prenatal testing. The PREcision Genetic Counseling And REproduction (PREGCARE) study is a new personalized assessment strategy that refines a couple's recurrence risk prior to a new pregnancy, by analyzing several samples from the parent-child trio (blood, saliva, swabs, and father's sperm) using deep sequencing and haplotyping. Overall, this approach can reassure ~2/3 of couples who have a negligible (<0.1%) recurrence risk and focus support on those at higher risk (i.e. when mosaicism is identified in one of the parents). Here we present a qualitative interview study with UK clinical genetics professionals (n = 20), which investigate the potential implications of introducing such a strategy in genetics clinics. While thematic analysis of the interviews indicated perceived clinical utility, it also indicates a need to prepare couples for the psychosocial implications of parent-of-origin information and to support their understanding of the assessment being offered. When dealing with personalized reproductive risk, a traditional non-directive approach may not meet the needs of practitioner and client(s) and shared decision-making provides an additional framework that may relieve some patient burden. Further qualitative investigation with couples is planned.

Perinatal Outcomes in Foetuses with Increased Nuchal Translucency and Normal Karyotype: A Retrospective Cohort Study from the United Arab Emirates

This retrospective case-controlled study analysed the outcome of pregnancies with first-trimester enlarged nuchal translucency (NT) and a normal karyotype. A total of 479 pregnancies with first-trimester NT measurements were grouped as control (370 cases; normal NT) and study (109 cases; enlarged NT, ≥95th percentile; with normal karyotype). Adverse outcomes included miscarriage, intrauterine foetal death, termination of pregnancy, neonatal death, and structural/chromosomal/genetic abnormalities. The study was conducted between June 2016 and June 2022 at the Foetal Maternal Unit of Kanad Hospital, UAE. Overall, the live birth rate in the study group was significantly lower (74.3%) compared to the control (94.1%, p < 0.001). All pregnancy outcomes of this group significantly differed compared to the control. The observed miscarriage level was 9.2% (vs. 1.1%, p < 0.001), intrauterine foetal death was 2.8% (vs. 0%, p = 0.001), spontaneous preterm birthwas 11% (vs. 4.9%, p = 0.020), and termination of pregnancy was 3.7% (vs. 0%, p < 0.001). The presence of foetal abnormalities was also significantly higher in the enlarged NT group at 21% (vs. 3.3%, p < 0.001). Results indicate that enlarged NT is associated with adverse pregnancy outcomes even when the karyotype is normal. Based on these results, a comprehensive review of the guidelines for counselling and managing pregnancies with enlarged NT and a normal karyotype is recommended.

Genetic Implications in High-Risk Pregnancy and Its Outcome: A 2-Year Study

OBJECTIVE

The aim of this study is to evaluate high-risk pregnant females' offspring as regard the presence of any medical condition, hereditary disorder, or major anomaly as well as to document parental sociodemographic characteristics and compliance with follow-up schedules of fetal medicine and clinical genetic clinics.

STUDY DESIGN

This prospective 2-year cohort study of neonates and infants reported the referral indications, investigations, and diagnoses obtained through prenatal and postnatal examinations. It also reported their parental follow-up vigilance.

RESULTS

Of the 811 infants of high risk females referred 460 (56.7%) came for assessment. Mean parental consanguinity and endogamy were 67 and 71.3%, respectively. All pregnant mothers underwent first-trimester biochemical testing (plasma protein-A, α-fetoprotein [AFP], human chorionic gonadotropin [hCG]) and serial ultrasound examinations. Seventy mothers needed second-trimester biochemical testing (AFP, hCG, and estriol). Sixty-two mothers underwent amniocentesis where G-banding karyotype, fluorescence in situ hybridization and targeted molecular testing for the specific gene mutation of single gene disorders were conducted according to suspected disorders. High quality fetal ultrasound was performed when brain malformations were suspected, while 16 fetuses required brain MRI examination. Mean age of newborns at first examination was 26.5 days. They were grouped according to the maternal indication for referral. Upon examination, 18 neonates had confirmed congenital malformations/genetic disorders. Five of them were diagnosed prenatally. In four other fetuses with single gene disorder, the molecular diagnosis of their affected siblings was not established prior to this pregnancy; thus, prenatal diagnosis was not possible. The remaining nine cases were diagnosed postnatally.

CONCLUSION

Parental consanguinity and endogamy were increased among high-risk pregnancies. Public awareness about potential adverse effects of consanguineous marriages and the importance of genetic testing are imperative. A structured multidisciplinary team of specialists in fetal medicine, clinical genetics, and neonatology provides good genetic services. Expansion and financial support of these services are urgently required.

KEY POINTS

· A multidisciplinary team provides good genetic services in high-risk pregnancies.. · Parental consanguinity and endogamy are increased among high-risk pregnancies.. · Increased public awareness about genetic testing importance and financial support are imperative..

Patient-facing genetic and genomic mobile apps in the UK: a systematic review of content, functionality, and quality

Close relative (consanguineous) marriage is widely practised globally, and it increases the risk of genetic disorders. Mobile apps may increase awareness and education regarding the associated risks in a sensitive, engaging, and accessible manner. This systematic review of patient-facing genetic/genomic mobile apps explores content, function, and quality. We searched the NHS Apps Library and the UK Google Play and Apple App stores for patient-facing genomic/genetic smartphone apps. Descriptive information and information on content was extracted and summarized. Readability was examined using the Flesch–Kincaid metrics. Two raters assessed each app, using the Mobile App Rating Scale (MARS) and the IMS Institute for Healthcare Informatics functionality score. A total of 754 apps were identified, of which 22 met the eligibility criteria. All apps intended to inform/educate users, while 32% analyzed genetic data, and 18% helped to diagnose genetic conditions. Most (68%) were clearly about genetics, but only 14% were affiliated with a medical/health body or charity, and only 36% had a privacy strategy. Mean reading scores were 35 (of 100), with the average reading age being equivalent to US grade 12 (UK year 13). On average, apps had 3.3 of the 11 IMS functionality criteria. The mean MARS quality score was 3.2 ± 0.7. Half met the minimum acceptability score (3 of 5). None had been formally evaluated. It was evident that there are few high-quality genomic/genetic patient-facing apps available in the UK. This demonstrates a need for an accessible, culturally sensitive, evidence-based app to improve genetic literacy within patient populations and specific communities.

Exome-based preconception carrier testing for consanguineous couples in China

OBJECTIVE

To evaluate the utility of clinical exome sequencing (ES)-based carrier screening in Chinese consanguineous couples.

METHODS

Consanguineous couples were screened for autosomal recessive (AR) disorders using the clinical ES of 5000 genes associated with human diseases.

RESULTS

We recruited 14 couples who elected to have sequencing. One couple was related as first cousins and 13 as second cousins. Both partners carrying the same pathogenic variant were detected in four couples. One couple was found in which one partner carried a splice variant, and the other had a missence variant of the same gene. These five couples were identified as being at risk of having a child affected by an AR disorder.

CONCLUSION

Our study demonstrates that ES-based preconception screening yields a clinical value for Chinese consanguineous couples. It enables to detect at-risk couples for rare AR diseases.

Mapping the Diverse Genetic Disorders and Rare Diseases Among the Syrian Population: Implications on Refugee Health and Health Services in Host Countries

The aim of this systematic review is to provide physicians and researchers with a comprehensive list of reported genetic disorders in patients of Syrian origin-those who have become part of the largest displaced population globally-and to highlight the need to consider migrant population-based risk for the development of genetic disease control and prevention programs. This review was performed based on the 2015 PRISMA and the international prospective register of systematic reviews. The present review reports on a total of 166 genetic disorders (only 128 reported on OMIM) identified in the Syrian population. Of these disorders, 27% are endocrine-, nutritional- and metabolic-related diseases. Second to metabolic disorders are congenital malformations, deformations and chromosomal abnormalities. Diseases of the blood and the blood-forming organs accounted for 13% of the total genetic disorders. The majority of the genetic disorders reported in Syrian patients followed an autosomal recessive mode of inheritance. These findings are a reflection of the high rates of consanguineous marriages that favor the increase in incidence of these diseases. From the diseases that followed an autosomal recessive mode of inheritance, 22% are reported to be only present in Syria and other regional countries. Twelve of these genetic diseases were identified to be strictly diagnosed in individuals of Syrian origin. The present systematic review highlights the need to develop programs that target genetic disorders affecting Syrian migrants in host countries. These programs would have potential financial and economic benefits, as well as a positive impact on the physical and mental health of members of the Syrian refugee community and those of their host societies. In turn, this would decrease the burden on the health systems in host countries.

Prenatal exposure to criteria air pollutants and associations with congenital anomalies: A Lebanese national study

Maternal exposure to air pollution has been associated with a higher birth defect (BD) risk. Previous studies suffer from inaccurate exposure assessment methods, confounding individual-level variations, and classical analytical modelling. This study aimed to examine the association between maternal exposure to criteria air pollutants and BD risk. A total of 553 cases and 10,214 controls were identified from private and public databases. Two subgroups were then formed: one for a matched case-control design, and another for Feature Selection (FS) analysis. Exposure assessment was based on the mean air pollutant-specific levels in the mother's residential area during the specific BD gestational time window of risk (GTWR) and other time intervals. Multivariate regression models outcomes consistently showed a significant protective effect for folic acid intake and highlighted parental consanguinity as a strong BD risk factor. After adjusting for these putative risk factors and other covariates, results show that maternal exposure to PM_2.5 during the first trimester is significantly associated with a higher overall BD risk (OR:1.05, 95%CI:1.01-1.09), and with a higher risk of genitourinary defects (GUD) (OR:1.06, 95%CI:1.01-1.11) and neural tube defects (NTD) (OR:1.10, 95%CI:1.03-1.17) during specific GTWRs. Maternal exposure to NO₂ during GTWR exhibited a significant protective effect for NTD (OR:0.94, 95%CI:0.90-0.99), while all other examined associations were not statistically significant. Additionally, maternal exposure to SO₂ during GTWR showed a significant association with a higher GUD risk (OR:1.17, 95%CI:1.08-1.26). When limiting selection to designated monitor coverage radiuses, PM_2.5 maintained significance with BD risk and showed a significant gene-environment interaction for GUD (p = 0.018), while NO₂ protective effect expanded to other subtypes. On the other hand, FS analysis confirmed maternal exposure to PM_2.5 and NO₂ as important features for GUD, CHD, and NTD. Our findings, set the basis for building a novel BD risk prediction model.

Parental exome analysis identifies shared carrier status for a second recessive disorder in couples with an affected child

Consanguinity, commonplace in many regions around the globe, is associated with an increased risk of autosomal recessive (AR) genetic disorders. Consequently, consanguineous couples undergoing preimplantation genetic diagnosis (PGD) for one Mendelian disorder may be at increased risk for a child with a second, unrelated AR genetic disorder. We examined the yield of exome analysis for carrier screening of additional AR disorders, beyond the primary diagnosis, amongst consanguineous vs. non-consanguineous populations. Parental samples from trio exomes of 102 consanguineous families and 105 non-consanguineous controls were evaluated for shared carrier status, after disregarding the primary molecular diagnosis. Results were sub-classified according to disease severity. Secondary shared carrier status for pathogenic and likely pathogenic variants leading to AR disorders of moderate to profound severity was identified in 10/102 (9.8%) consanguineous couples, as compared to 1/105 (0.95%) non-consanguineous couples (χ² = 8.0565, p value < 0.005). Higher inbreeding coefficient values, calculated from individual exomes, correlated with secondary shared carrier status for diseases of moderate to profound severity (r = 0.17, p value < 0.0125). Our results indicate that consanguineous couples undergoing PGD are at increased risk for a second genetic disease of moderate to profound severity. This study represents an underestimate of the rate of secondary shared carrier status due to inability to detect deep intronic variants, no assessment of copy number variants, and false negative results stemming from stringent variant interpretation. False positive results may result from inaccuracies in public databases. Additional studies in consanguineous populations will determine whether exome-based carrier screening should be recommended to all couples undergoing PGD.

Genetic counseling of high-risk isolated populations: A worldwide challenge

BACKGROUND

Isolated populations with high rates of consanguinity and genetic disorders can be found in most parts of the world. The aim of our paper was to highlight the unique challenges faced in genetic counseling for such patients and to discuss the ways to facilitate the difficulties, with an emphasis on the crucial role of electronic medical records (EMR).

CASE

We report a couple presenting with elevated maternal alpha-fetoprotein in three pregnancies, in which an erroneous diagnosis of epidermolysis bullosa was established in the past and carried along through several years. The live born proband had no evidence of skin disease; however, soon after birth she was diagnosed with congenital nephrotic syndrome. Sequencing of NPHS1 gene yielded a homozygous likely pathogenic genetic variant c.2104G > A (p.Gly702Arg). Population screening performed in the village of residence revealed a carrier frequency of 1-47. This high frequency justified including testing for the founder genetic variant in the national program for population screening.

CONCLUSIONS

Our report highlights the caution, suspicion and time investment which should be practiced and addressed in genetic counseling of high-risk isolated populations. Using EMR may facilitate reaching the correct diagnosis, enable accurate genetic counseling and provide information for decision-making to the couples, as well as "save" a large community from devastating diseases.

Next-generation sequencing in prenatal setting: Some examples of unexpected variant association

The application of next-generation sequencing to fetal pathology has proved to increase the diagnostic yield in fetuses with abnormal ultrasounds. We retrospectively reviewed genetic data of 30 selected cases studied through targeted resequencing of OMIM genes. In our experience, clinical data proved to be essential to support diagnostic reasoning and enhance variants' assessment. The molecular diagnosis was reached in 19/30 (63%) cases. Only in 7/19 cases the molecular diagnosis confirmed the initial diagnostic hypothesis, showing the relevance of the genotype-first approach. According to the genotype-phenotype correlation, we were able to divide the solved cases into three groups: i) the correlation is well established but it was missed due to lack of specificity, unusual presentation or recent description; ii) the clinical presentation is much more severe than currently known for the underlying condition; iii) the correlation does not recapitulate the entire phenotype, possibly due to the fetal presentation or multiple coexisting conditions. Moreover, we found a higher proportion of recessive diagnosis in abnormal fetuses compared to cohorts of individuals with developmental delay. Our findings suggest that fetal pathology may be enriched in rare alleles and/or in unusual combinations, counter-selected in postnatal genomes and thus contributing to both phenotypic extremeness and atypical presentation.

Consanguineous marriage and its effect on reproductive behavior and uptake of prenatal screening

The study aimed to determine the prevalence of consanguinity among pregnant women, its effect on reproductive behavior and the uptake of prenatal screening. The sample consisted of 842 pregnant women recruited to a prospective cohort study conducted in twenty-three cities from different regions in Turkey between June 2017 and March 2018. Of the women, 17.7% (n = 149) were in consanguineous marriages. The consanguineous couples were younger at the time of their marriages than non-consanguineous couples, and 49% of the consanguineous marriages were arranged. The educational levels of both spouses in consanguineous marriages were lower than those in non-consanguineous marriages. There was a statistically significant difference in the prevalence of the pregnant women having a prenatal screening test between women in consanguineous marriages (53%) and those in non-consanguineous marriages (78.2%). There were no statistically significant differences between the two groups in terms of having health problems during pregnancy, the number of pregnancies, abortions and/or stillbirths, the week of delivery and the birthweight of the baby. Healthcare providers play a key role in eliciting whether or not pregnant couples are consanguineous, providing a tailored risk assessment, education, and counseling about screening and diagnostic tests for early diagnosis and management of the fetus, explaining the testing process and possible outcomes, and helping couples make informed decisions regarding their reproductive options or pregnancy management.

How should health policy and practice respond to the increased genetic risk associated with close relative marriage? results of a UK Delphi consensus building exercise

OBJECTIVES

(1) To explore professional and lay stakeholder views on the design and delivery of services in the area of consanguinity and genetic risk. (2) To identify principles on which there is sufficient consensus to warrant inclusion in a national guidance document. (3) To highlight differences of opinion that necessitate dialogue. (4) To identify areas where further research or development work is needed to inform practical service approaches.

DESIGN

Delphi exercise. Three rounds and one consensus conference.

SETTING

UK, national, web-based and face-to-face.

PARTICIPANTS

Recruitment via email distribution lists and professional networks. 42 participants with varied professional and demographic backgrounds contributed to at least one round of the exercise. 29 people participated in statement ranking across both rounds 2 and 3.

RESULTS

Over 700 individual statements were generated in round 1 and consolidated into 193 unique statements for ranking in round 2, with 60% achieving 80% or higher agreement. In round 3, 74% of statements achieved 80% or higher agreement. Consensus conference discussions resulted in a final set of 148 agreed statements, providing direction for both policy-makers and healthcare professionals. 13 general principles were agreed, with over 90% agreement on 12 of these. Remaining statements were organised into nine themes: national level leadership and coordination, local level leadership and coordination, training and competencies for healthcare and other professionals, genetic services, genetic literacy, primary care, referrals and coordination, monitoring and evaluation and research. Next steps and working groups were also identified.

CONCLUSIONS

There is high agreement among UK stakeholders on the general principles that should shape policy and practice responses in this area: equity of access, cultural competence, coordinated inter-agency working, co-design and empowerment and embedded evaluation. The need for strong national leadership to ensure more efficient sharing of knowledge and promotion of more equitable and consistent responses across the country is emphasised.

Improving case ascertainment of congenital anomalies: findings from a prospective birth cohort with detailed primary care record linkage

BACKGROUND

Congenital anomalies (CAs) are a common cause of infant death and disability. We linked children from a large birth cohort to a routine primary care database to detect CA diagnoses from birth to age 5 years. There could be evidence of underreporting by CA registries as they estimate that only 2% of CA registrations occur after age 1 year.

METHODS

CA cases were identified by linking children from a prospective birth cohort to primary care records. CAs were classified according to the European Surveillance of CA guidelines. We calculated rates of CAs by using a bodily system group for children aged 0 to <5 years, together with risk ratios (RRs) with 95% CIs for maternal risk factors.

RESULTS

Routinely collected primary care data increased the ascertainment of children with CAs from 432.9 per 10 000 live births under 1 year to 620.6 per 10 000 live births under 5 years. Consanguinity was a risk factor for Pakistani mothers (multivariable RR 1.87, 95% CI 1.46 to 2.83), and maternal age >34 years was a risk factor for mothers of other ethnicities (multivariable RR 2.19, 95% CI 1.36 to 3.54). Education was associated with a lower risk (multivariable RR 0.78, 95% CI 0.62 to 0.98).

CONCLUSION

98% of UK CA registrations relate to diagnoses made in the first year of life. Our data suggest that this leads to incomplete case ascertainment with a further 30% identified after age 1 year in our study. Risk factors for CAs identified up to age 1 year persist up to 5 years. National registries should consider using routine data linkage to provide more complete case ascertainment after infancy.