Bi-allelic Loss-of-Function CACNA1B Mutations in Progressive Epilepsy-Dyskinesia

The occurrence of non-epileptic hyperkinetic movements in the context of developmental epileptic encephalopathies is an increasingly recognized phenomenon. Identification of causative mutations provides an important insight into common pathogenic mechanisms that cause both seizures and abnormal motor control. We report bi-allelic loss-of-function CACNA1B variants in six children from three unrelated families whose affected members present with a complex and progressive neurological syndrome. All affected individuals presented with epileptic encephalopathy, severe neurodevelopmental delay (often with regression), and a hyperkinetic movement disorder. Additional neurological features included postnatal microcephaly and hypotonia. Five children died in childhood or adolescence (mean age of death: 9 years), mainly as a result of secondary respiratory complications. CACNA1B encodes the pore-forming subunit of the pre-synaptic neuronal voltage-gated calcium channel Ca_v2.2/N-type, crucial for SNARE-mediated neurotransmission, particularly in the early postnatal period. Bi-allelic loss-of-function variants in CACNA1B are predicted to cause disruption of Ca²⁺ influx, leading to impaired synaptic neurotransmission. The resultant effect on neuronal function is likely to be important in the development of involuntary movements and epilepsy. Overall, our findings provide further evidence for the key role of Ca_v2.2 in normal human neurodevelopment.

Prenatal exome sequencing analysis in fetal structural anomalies detected by ultrasonography (PAGE): a cohort study

BACKGROUND

Fetal structural anomalies, which are detected by ultrasonography, have a range of genetic causes, including chromosomal aneuploidy, copy number variations (CNVs; which are detectable by chromosomal microarrays), and pathogenic sequence variants in developmental genes. Testing for aneuploidy and CNVs is routine during the investigation of fetal structural anomalies, but there is little information on the clinical usefulness of genome-wide next-generation sequencing in the prenatal setting. We therefore aimed to evaluate the proportion of fetuses with structural abnormalities that had identifiable variants in genes associated with developmental disorders when assessed with whole-exome sequencing (WES).

METHODS

In this prospective cohort study, two groups in Birmingham and London recruited patients from 34 fetal medicine units in England and Scotland. We used whole-exome sequencing (WES) to evaluate the presence of genetic variants in developmental disorder genes (diagnostic genetic variants) in a cohort of fetuses with structural anomalies and samples from their parents, after exclusion of aneuploidy and large CNVs. Women were eligible for inclusion if they were undergoing invasive testing for identified nuchal translucency or structural anomalies in their fetus, as detected by ultrasound after 11 weeks of gestation. The partners of these women also had to consent to participate. Sequencing results were interpreted with a targeted virtual gene panel for developmental disorders that comprised 1628 genes. Genetic results related to fetal structural anomaly phenotypes were then validated and reported postnatally. The primary endpoint, which was assessed in all fetuses, was the detection of diagnostic genetic variants considered to have caused the fetal developmental anomaly.

FINDINGS

The cohort was recruited between Oct 22, 2014, and June 29, 2017, and clinical data were collected until March 31, 2018. After exclusion of fetuses with aneuploidy and CNVs, 610 fetuses with structural anomalies and 1202 matched parental samples (analysed as 596 fetus-parental trios, including two sets of twins, and 14 fetus-parent dyads) were analysed by WES. After bioinformatic filtering and prioritisation according to allele frequency and effect on protein and inheritance pattern, 321 genetic variants (representing 255 potential diagnoses) were selected as potentially pathogenic genetic variants (diagnostic genetic variants), and these variants were reviewed by a multidisciplinary clinical review panel. A diagnostic genetic variant was identified in 52 (8·5%; 95% CI 6·4-11·0) of 610 fetuses assessed and an additional 24 (3·9%) fetuses had a variant of uncertain significance that had potential clinical usefulness. Detection of diagnostic genetic variants enabled us to distinguish between syndromic and non-syndromic fetal anomalies (eg, congenital heart disease only vs a syndrome with congenital heart disease and learning disability). Diagnostic genetic variants were present in 22 (15·4%) of 143 fetuses with multisystem anomalies (ie, more than one fetal structural anomaly), nine (11·1%) of 81 fetuses with cardiac anomalies, and ten (15·4%) of 65 fetuses with skeletal anomalies; these phenotypes were most commonly associated with diagnostic variants. However, diagnostic genetic variants were least common in fetuses with isolated increased nuchal translucency (≥4·0 mm) in the first trimester (in three [3·2%] of 93 fetuses).

INTERPRETATION

WES facilitates genetic diagnosis of fetal structural anomalies, which enables more accurate predictions of fetal prognosis and risk of recurrence in future pregnancies. However, the overall detection of diagnostic genetic variants in a prospectively ascertained cohort with a broad range of fetal structural anomalies is lower than that suggested by previous smaller-scale studies of fewer phenotypes. WES improved the identification of genetic disorders in fetuses with structural abnormalities; however, before clinical implementation, careful consideration should be given to case selection to maximise clinical usefulness.

FUNDING

UK Department of Health and Social Care and The Wellcome Trust.

The clinical utility of genetic testing of tissues from pregnancy losses

OBJECTIVE

To map the current testing being undertaken following pregnancy loss across the UK and to examine the clinical utility in terms of identifying a cause for the loss and in identifying couples at risk of an unbalanced liveborn child.

DESIGN

Retrospective audit.

SETTING

UK, for the year 2014.

POPULATION

An audit of 6465 referrals for genetic testing of tissue samples following pregnancy loss.

METHODS

Data were obtained by questionnaire from 15 UK regional genetics laboratories.

MAIN OUTCOME MEASURES

Data were analysed with respect to gestational age, the presence of identified fetal anomalies, methodologies used, abnormality rates and the presence of a parental balanced rearrangement.

RESULTS

Of 6465 referrals a genetic cause was identified in 22% of cases (before 12 weeks' gestation, in 47%; at 12-24 weeks, in 14%; after 24 weeks, in 6%). In 0.4% of cases a balanced parental rearrangement was identified where there was a risk of an affected liveborn child in a future pregnancy. Eighty percent of genetic imbalances identified were aneuploidy or triploidy and could be identified by quantitative fluorescence polymerase chain reaction alone. There was significant variation across the UK in acceptance criteria, testing strategies and thus level of resolution of testing.

CONCLUSIONS

Genetic testing of tissues following pregnancy loss identifies a probable cause of fetal demise in 22% of cases, but it is of low clinical utility in identifying couples at risk of a future unbalanced liveborn child. A comprehensive multidisciplinary review is needed to develop proposals for an affordable and equitable service.

TWEETABLE ABSTRACT

UK audit of genetic testing of fetal loss shows variation in access to and resolution of analysis.

Systematic review and meta-analysis of the association between frailty and outcome in surgical patients

INTRODUCTION

Frailty is becoming increasingly prevalent in the elderly population although a lack of consensus regarding a clinical definition hampers comparison of clinical studies. More elderly patients are being assessed for surgical intervention but the effect of frailty on surgical related outcomes is still not clear.

METHODS

A systematic literature search for studies prospectively reporting frailty and postoperative outcomes in patients undergoing surgical intervention was performed with data collated from a total of 12 studies. Random effects meta-analysis modelling was undertaken to estimate the association between frailty and mortality rates (in-hospital and one-year), length of hospital stay and the need for step-down care for further rehabilitation/nursing home placement.

RESULTS

Frailty was associated with a higher in-hospital mortality rate (pooled odds ratio [OR]: 2.77, 95% confidence interval [CI]: 1.62-4.73), a higher one-year mortality rate (pooled OR: 1.99, 95% CI: 1.49-2.66), a longer hospital stay (pooled mean difference: 1.05 days, 95% CI: 0.02-2.07 days) and a higher discharge rate to further rehabilitation/step-down care (pooled OR: 5.71, 95% CI: 3.41-9.55).

CONCLUSIONS

The presence of frailty in patients undergoing surgical intervention is associated with poorer outcomes with regard to mortality and return to independence. Further in-depth studies are required to identify factors that can be optimised to reduce the burden of frailty in surgical patients.

Large-scale discovery of novel genetic causes of developmental disorders

Despite three decades of successful, predominantly phenotype-driven discovery of the genetic causes of monogenic disorders, up to half of children with severe developmental disorders of probable genetic origin remain without a genetic diagnosis. Particularly challenging are those disorders rare enough to have eluded recognition as a discrete clinical entity, those with highly variable clinical manifestations, and those that are difficult to distinguish from other, very similar, disorders. Here we demonstrate the power of using an unbiased genotype-driven approach to identify subsets of patients with similar disorders. By studying 1,133 children with severe, undiagnosed developmental disorders, and their parents, using a combination of exome sequencing and array-based detection of chromosomal rearrangements, we discovered 12 novel genes associated with developmental disorders. These newly implicated genes increase by 10% (from 28% to 31%) the proportion of children that could be diagnosed. Clustering of missense mutations in six of these newly implicated genes suggests that normal development is being perturbed by an activating or dominant-negative mechanism. Our findings demonstrate the value of adopting a comprehensive strategy, both genome-wide and nationwide, to elucidate the underlying causes of rare genetic disorders.

The challenge of a 2-year follow-up after intervention for weight loss in primary care

BACKGROUND

Many weight loss programmes show short-term success, but long-term data in larger studies are scarce, especially in community settings. Attrition is common and complicates the interpretation of long-term outcomes.

OBJECTIVE

To investigate 2-year outcomes and explore issues of attrition and missing data.

SUBJECTS

A total of 772 overweight and obese adults recruited by primary care practices in Australia, Germany and the UK and randomised to a 12-month weight loss intervention delivered in a commercial programme (CP) or in standard care (SC).

MEASUREMENT

Weight change from 0-24 and 12-24 months including measured weights only and measured and self-reported weights, using last observation carried forward (LOCF), baseline observation carried forward (BOCF), completers-only and missing-at-random (MAR) analyses.

RESULTS

A total of 203 participants completed the 24-month visit. Using measured weights only, there was a trend for greater 24-month weight loss in CP than in SC, but the difference was only statistically significant in the LOCF and BOCF analyses: LOCF: -4.14 vs -1.99 kg, difference adjusted for centre -2.08 kg, P<0.001; BOCF: -1.33 vs -0.74 kg, adjusted difference -0.60 kg, P=0.032; completers: -4.76 vs -2.99 kg, adjusted difference -1.53 kg, P=0.113; missing at random: -3.00 vs -1.94 kg, adjusted difference -1.04 kg, P=0.150. Both groups gained weight from 12-24 months and weight regain was significantly (P<0.001) greater for CP than for SC in all analysis approaches. Inclusion of self-reported weights from a further 138 participants did not change the interpretation of the findings.

CONCLUSION

Initial weight loss was poorly maintained during the no-intervention follow-up, but both groups did have lower weight over the 24 months. Attrition was high in both groups, and assumptions about missing data had considerable impact on the magnitude and statistical significance of treatment effects. It is vital that trials on weight loss interventions consider the plausibility of these differences in an analytical approach when interpreting research findings and comparing data between studies.

Case series: 2q33.1 microdeletion syndrome--further delineation of the phenotype

Recurrent deletions of 2q32q33 have recently been reported as a new microdeletion syndrome, clinical features of which include significant learning difficulties, growth retardation, dysmorphic features, thin and sparse hair, feeding difficulties, and cleft or high palate. Haploinsufficiency of one gene within the deleted region, SATB2, has been suggested to be responsible for most of the features of the syndrome. This article describes seven previously unreported patients with deletions at 2q33.1, all partially overlapping the previously described critical region for the 2q33.1 microdeletion syndrome. The deletions ranged in size from 35 kb to 10.4 Mb, with the smallest deletion entirely within the SATB2 gene. Patients demonstrated significant developmental delay and challenging behaviour, a particular behavioural phenotype that seems to be emerging with more reported patients with this condition. One patient in this cohort has a deletion entirely within SATB2 and has a cleft palate, whereas several patients with larger deletions have a high arched palate. In addition, one other patient has significant orthopaedic problems with ligamentous laxity. Interestingly, this patient has a deletion that lies just distal to SATB2. The orthopaedic problems have not been reported previously and are possibly an additional feature of this syndrome. Overall, this report provides further evidence that the SATB2 gene is the critical gene in this microdeletion syndrome. In addition, because the individuals in this study range in age from 3-19 years, these patients will help define the natural progression of the phenotype in patients with this microdeletion.

A double-blind study of hyposensitization with an alginate conjugated extract of D. pteronyssinus (Conjuvac) in patients with perennial rhinitis. 1. Clinical aspects

The efficacy of hyposensitization with a standardised extract of Dermatophagoides pteronyssinus (D. pteronyssinus) conjugated to alginate and containing known amounts of antigen P1 (Conjuvac) was tested in a double blind, placebo controlled, multi-centre study in 66 adult patients with perennial rhinitis. Patients received 11 weekly injections of increasing concentrations of Conjuvac containing from 56 x 10(1) to 448 10(3) IU D. pteronyssinus or placebo injections of the alginate diluent to some of which 5 micrograms of histamine has been randomly added. This was followed by 15 monthly injections of Conjuvac or placebo. The severity of nasal blockage, sneezing and rhinorrhoea was recorded twice daily in a diary and visual analogue assessments (VAS) made at each clinic visit. Nasal provocation testing (NPT) was performed with increasing concentrations of the same extract of D. pteronyssinus as used in the hyposensitization injections, and changes in nasal airways resistance measured by passive anterior rhinomanometry. VAS was recorded and NPT was performed on entry to the study and after the fifth, ninth and final monthly injection. Conjuvac injections were well tolerated. Large local reactions (greater than 5 cm) occurred within 30 min in only 1% of patients but later in 23%. No systemic reactions or anaphylaxis occurred within 30 min of injections, but urticaria or worsening of asthma and rhinitis was reported later in 3% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)