Diagnosis of inborn errors of metabolism through prenatal exome sequencing with targeted analysis for fetal structural anomalies

OBJECTIVES

The value of prenatal exome sequencing (pES) for fetuses with structural anomalies is widely reported. In England, testing is conducted through trio exome sequencing and analysis of a gene panel. Over a 30-month period testing of 921 pregnancies resulted in a genetic diagnosis in 32.8% of cases (302/921). Here we review cases diagnosed with an inborn error of metabolism.

METHODS

Diagnoses of inborn errors of metabolism (IEM) were classified according to the ICIMD classification system. Genetic diagnoses were assessed against Human Phenotype Ontology terms, gestation of scan findings and literature evidence.

RESULTS

35/302 diagnoses (11.6%) represented IEM. Almost half affected metabolism of complex macromolecules and organelles (n = 16), including congenital disorders of glycosylation (n = 8), peroxisome biogenesis disorders (n = 4), and lysosomal storage disorders (n = 4). There were eight disorders of lipid metabolism and transport, the majority being genes in the cholesterol biosynthesis pathway, eight disorders of intermediary metabolism, of which seven were defects in "energy" processes, and two diagnoses of alkaline phosphatase deficiency.

CONCLUSIONS

Review of pES diagnoses and ultrasound scan findings is key to understanding genotype-phenotype correlations. IEM are genetically heterogeneous and may present with variable scan findings, which makes an individual diagnosis difficult to suspect. Diagnosis during pregnancy is particularly important for many IEM with respect to prognosis and early neonatal management.

Molecular autopsy for fetal structural anomaly: diagnostic and clinical utility of multidisciplinary team approach

OBJECTIVES

In the West Midlands Regional Genetic Service, cases of perinatal death with a possible genetic diagnosis are evaluated by the Perinatal Pathology Genetic Multidisciplinary Team (MDT). The MDT assessed autopsy findings and considered genomic assessments. The objective of this retrospective service evaluation was to determine the clinical utility of the MDT. This is the first evaluation since the introduction of whole genome and whole exome sequencing in routine clinical care.

METHOD

The outcomes for all the perinatal MDT cases from January 2021 to December 2021 were examined. All cases received a full or partial post-mortem examination (PM) and a chromosomal microarray. Demographics, phenotype, MDT recommendations, genetic testing, diagnoses, outcomes, impact of PM and impact of genetic testing were collected from patient case notes.

RESULTS

One hundred and twenty-three cases were discussed at the MDT meeting in 2021. Genetic evaluation was recommended in 84 cases and accepted in 64 cases. A range of genetic tests were requested according to indication and availability. Thirty diagnoses were identified in 29 cases from 26 unrelated families. The diagnostic yield was 24% (29/123) of all cases or 45% (29/64) of the cases with a suspected genetic diagnosis who underwent genetic testing. PM examination added clinically actionable phenotype data in 79% of cases. A genetic diagnosis enabled accurate counselling of recurrence risk and provision of appropriate follow-up, including prenatal testing and preimplantation diagnosis for patients with inherited conditions.

CONCLUSIONS

Genomic testing was a clinically useful addition to (but not a substitute for) PM examination in perinatal cases associated with structural anomalies. The MDT model helped assess cases and plan appropriate follow-up. Expedited whole genome sequencing or panel-agnostic analysis were most appropriate for heterogeneous presentations. This broad approach can also expand prenatal phenotypes and detect novel disease genes and should be a priority for future research. This article is protected by copyright. All rights reserved.

Prenatal diagnosis of PORCN-related developmental syndrome in a fetus: A novel phenotype

We report a case of a female fetus born to an unrelated couple with a complex fetal phenotype of a pleural effusion, a cardiac malformation, and syndactyly of the toes. Prenatal exome sequencing identified a variant of uncertain significance in the PORCN gene that was upgraded to likely pathogenic following postnatal clinical examination. The phenotype described in cases with variants in the PORCN gene is often associated with findings that cannot be prospectively diagnosed by ultrasonography. This is the first report of a prenatal phenotype involving a fetal effusion associated with variants in the PORCN gene, with skeletal findings identified later in gestation on ultrasonography. The diagnosis was confirmed on neonatal examination.

Prevalence of pre-eclampsia and adverse pregnancy outcomes in women with pre-existing cardiomyopathy: a multi-centre retrospective cohort study

Pre-eclampsia is associated with postnatal cardiac dysfunction; however, the nature of this relationship remains uncertain. This multicentre retrospective cohort study aimed to determine the prevalence of pre-eclampsia in women with pre-existing cardiac dysfunction (left ventricular ejection fraction < 55%) and explore the relationship between pregnancy outcome and pre-pregnancy cardiac phenotype. In this cohort of 282 pregnancies, pre-eclampsia prevalence was not significantly increased (4.6% [95% C.I 2.2-7.0%] vs. population prevalence of 4.6% [95% C.I. 2.7-8.2], p = 0.99); 12/13 women had concurrent obstetric/medical risk factors for pre-eclampsia. The prevalence of preterm pre-eclampsia (< 37 weeks) and fetal growth restriction (FGR) was increased (1.8% vs. 0.7%, p = 0.03; 15.2% vs. 5.5%, p < 0.001, respectively). Neither systolic nor diastolic function correlated with pregnancy outcome. Antenatal ß blockers (n = 116) were associated with lower birthweight Z score (adjusted difference - 0.31 [95% C.I. - 0.61 to - 0.01], p = 0.04). To conclude, this study demonstrated a modest increase in preterm pre-eclampsia and significant increase in FGR in women with pre-existing cardiac dysfunction. Our results do not necessarily support a causal relationship between cardiac dysfunction and pre-eclampsia, especially given the population's background risk status. The mechanism underpinning the relationship between cardiac dysfunction and FGR merits further research but could be influenced by concomitant ß blocker use.

Cardiac function in pregnant women with a Fontan circulation following live birth

Background

Fontan circuits are used to palliate congenital heart disease where patients have a single functioning ventricle. The venous return to the heart is redirected to the pulmonary arteries through the use of a conduit, bypassing the heart. Many females with Fontan circuits are now reaching child-bearing age and some desire pregnancy. However, pregnancy in women with Fontan circuits is associated with high complication rates.

Purpose

We compared postnatal cardiac function in women with a Fontan circulation with pre-pregnancy cardiovascular investigations.

Methods

Data were collected from case notes of all women with a Fontan circulation giving birth after 24 weeks of gestation at Birmingham Women's Hospital between 1997 and 2019.

Results

18 women with a median age of 29±6 years were followed up for 8.0±9 years. There were 21 live births at a median gestation of 32±5 weeks, of which 81% were caesarean sections. Three infants (14%) were born before 30 weeks' gestation and only two (10%) at term. Significant dyspnoea complicated 19% of pregnancies and postpartum haemorrhage occurred in 24%.

Pre-pregnancy cardiac magnetic resonance (CMR) data were available for 11 women and post-pregnancy for 14. Post-pregnancy scans were performed a median of 1.5±4.8 years after birth. Ejection fraction was 63.6±5% at baseline and tended to reduce following pregnancy (median −5.0±8%, n=7). Pre-pregnancy peak oxygen consumption (VO2max) was 73±14% of predicted on cardiopulmonary exercise testing. Median change in VO2max was −8±22% post-pregnancy (n=4). There was no change New York Heart Association (NYHA) class or resting saturations after pregnancy.

Conclusions

Preterm delivery and maternal bleeding were prevalent in this cohort. Exercise capacity was moderately impaired and saturations were typically low. Pregnancy does not seem to have longer term impact on oxygen saturations or NYHA class. Larger series are needed to confirm whether pregnancy is detrimental to postpartum systolic function. CMR can give comprehensive assessment of cardiac function before and after pregnancy and provide data to inform the crucial pre-pregnancy counselling for Fontan patients of child-bearing age.

Funding Acknowledgement

Type of funding source: None

A comparison of teaching strategies for integrating information technology into clinical nursing education

As health care becomes more information-intensive and diverse, there is a need to integrate information technology (IT) into clinical education. Little is known, however, about how to design instructional strategies for integrating information technology into clinical nursing education. This article outlines the instructional strategies used by faculty in five nursing programs who taught students to use a point-of-care information technology system. The article also reports students' computer acceptance and summarizes IT clinical teaching recommendations.

One nurse's experience with technology

This article examines the positive and negative aspects of working with a documentation and information management system from the unique perspective of a practicing home care nurse who was also a student. Aspects of the nightingale tracker technology that are comparable with others used in home care, experiences of field testing, and the nurse's observations can help home care nurses see how this technology can benefit their practice.

Studies of intracellular distribution of acid phosphatase 5 in the spleen cells of leukemic reticuloendotheliosis by isopycnic gradient centrifugation

A fresh spleen sample obtained from a patient with leukemic reticuloendotheliosis was homogenized and subjected to centrifugation on a sucrose density gradient. A major portion of acid phosphatase band 5 was observed in the lysosome, confirming that the elevated phosphatase activity in the neoplastic spleen is a lysosomal enzyme. However, a significant amount of brand 5 was also observed in the microsome. The microsomal and lysosomal enzymes have different affinity to CM-cellulose. The relationship between lysosomal and microsomal enzymes has not been established.