Molecular genetic screening after non-ischaemic sudden cardiac arrest and no overt cardiomyopathy in real life: A major tool for the aetiological diagnostic work-up

BACKGROUND

With the development of advanced sequencing techniques, genetic testing has emerged as a valuable tool for the work-up of non-ischaemic sudden cardiac arrest (SCA).

AIMS

To evaluate the effectiveness of genetic testing in patients with unexplained SCA, according to clinical phenotype.

METHODS

All patients who underwent molecular genetic testing for non-ischaemic SCA with no left ventricular cardiomyopathy between 2012 and 2021 in two French university hospitals were included.

RESULTS

Of 66 patients (mean age 36.7±11.9years, 54.5% men), 21 (31.8%; 95% confidence interval 22.4-45.3%) carried a genetic variant: eight (12.1%) had a pathogenic or likely pathogenic (P/LP) variant and 13 (19.7%) had a variant of uncertain significance (VUS). Among 37 patients (56.1%) with no phenotypic clues, genetic testing identified a P/LP variant in five (13.5%), mainly in RYR2 (n=3) and SCN5A (n=2), and a VUS in nine (24.3%). None of the nine patients with phenotypic evidence of channelopathies had P/LP variants, but two had VUS in RYR2 and NKX2.5. Among the 20 patients with suspected arrhythmogenic cardiomyopathy, three P/LP variants (15.0%) and two VUS (10.0%) were found in DSC2, PKP2, SCN5A and DSG2, TRPM4, respectively. Genetic testing was performed sooner after cardiac arrest (P<0.001) and results were obtained more rapidly (P=0.02) after versus before 2016.

CONCLUSION

This study highlights the utility of molecular genetic testing with a genetic variant of interest identified in one-third of patients with unexplained SCA. Genetic testing was beneficial even in patients without phenotypic clues, with one-fourth of patients carrying a P/LP variant that could have direct implications.

Saw-Tooth Cardiomyopathy

Saw-tooth cardiomyopathy is a very rare disease, and only few cases have been published since its first description 10 years ago. We report the clinical presentation, imaging features and genetic analysis of a saw-tooth cardiomyopathy and argues that it should not be confused with left-ventricular noncompaction. (Level of Difficulty: Intermediate.)

Clinical impact of post-mortem genetic testing in cardiac death and cardiomyopathy

Post-mortem genetic analyses may help to elucidate the cause of cardiac death. The added value is however unclear when a cardiac disease is already suspected or affirmed. Our aim was to study the feasibility and medical impact of post-mortem genetic analyses in suspected cardiomyopathy. We studied 35 patients with cardiac death and suspected cardiomyopathy based on autopsy or clinical data. After targeted sequencing, we identified 15 causal variants in 15 patients (yield 43%) in sarcomeric (n = 8), desmosomal (n = 3), lamin A/C (n = 3) and transthyretin (n = 1) genes. The results had various impacts on families, i.e. allowed predictive genetic testing in relatives (15 families), planned early therapeutics based on the specific underlying gene (5 families), rectified the suspected cardiomyopathy subtype (2 families), assessed the genetic origin of cardiomyopathy that usually has an acquired cause (1 family), assessed the diagnosis in a patient with uncertain borderline cardiomyopathy (1 family), reassured the siblings because of a de novo mutation (2 families) and allowed prenatal testing (1 family). Our findings suggest that post-mortem molecular testing should be included in the strategy of family care after cardiac death and suspected cardiomyopathy, since genetic findings provide additional information useful for relatives, which are beyond conventional autopsy.

Psychosocial Impact of Predictive Genetic Testing in Hereditary Heart Diseases: The PREDICT Study

Predictive genetic testing (PGT) is offered to asymptomatic relatives at risk of hereditary heart disease, but the impact of result disclosure has been little studied. We evaluated the psychosocial impacts of PGT in hereditary heart disease, using self-report questionnaires (including the State-Trait Anxiety Inventory) in 517 adults, administered three times to the prospective cohort (PCo: n = 264) and once to the retrospective cohort (RCo: n = 253). The main motivations for undergoing PGT were “to remove doubt” and “for their children”. The level of anxiety increased between pre-test and result appointments (p <0.0001), returned to baseline after the result (PCo), and was moderately elevated at 4.4 years (RCo). Subjects with a history of depression or with high baseline anxiety were more likely to develop anxiety after PGT result (p = 0.004 and p <0.0001, respectively), whatever it was. Unfavourable changes in professional and/or family life were observed in 12.4% (PCo) and 18.7% (RCo) of subjects. Few regrets about PGT were expressed (0.8% RCo, 2.3% PCo). Medical benefit was not the main motivation, which emphasises the role of pre/post-test counselling. When PGT was performed by expert teams, the negative impact was modest, but careful management is required in specific categories of subjects, whatever the genetic test result.

P891Psycho-social impact of predictive genetic testing in hereditary heart diseases (PREDICT Study)

Introduction

Hereditary heart diseases are most often characterized by autosomal dominant inheritance and delayed cardiac expression. Predictive genetic testing is offered to asymptomatic relatives to allow targeted medical care with early therapeutics in order to reduce the risk of complications. Psychological issues and socio-professional impact of predictive testing are complex and have been poorly studied. The aim of this study was to evaluate the psychological and socio-professional impact of predictive genetic testing in hereditary heart diseases through a prospective and retrospective study.

Patients and methods

This multicentric French study involved 20 expert centers in hereditary heart diseases. We included 517 adult relatives (42.3±16.7 years, 60.6% females) who performed predictive genetic testing (prospective study: N=264, retrospective study: N=253). The opinion and experience were collected via auto-questionnaires, at various moments in the prospective study, with different items and validated scales (STAI: score for anxiety and IES: impact of event).

Results

In the prospective study, family history was characterized by cardiomyopathy (88.4%) and channelopathies (11.6%). The main motivations for performing the test were: “to remove doubt” (65.3%), “for children” (64.0%), “to benefit from medical supervision” (34.9%). A mutation was present in 39.4% of relatives. No regret was expressed after testing (only 2.3% regrets). The result did not lead to a socio-professional change or family relationship change in 60.7%. Among those who had a change, it was perceived as unfavorable for only 3%. A change in socio-professional status and/or family relationship was mainly related to the result of genetic testing (p<0.0001). The level of anxiety (STAI scale) increased before the test result but then decreased and returned to baseline. Subjects with depression history were more likely to develop anxiety at long term after multivariate analyses (p=0.004). Quite similar results were observed in the retrospective study.

Conclusions

Our results show that contrary to a widespread opinion, the medical benefit was not the main motivation for predictive genetic testing. In most cases, no or marginal adverse psychological and socio-professional impact of genetic testing was observed when performed by a team expert in predictive testing. However careful management is required to identify and manage subjects at risk for increased anxiety or socio-professional change.

Acne relapses: impact on quality of life and productivity

BACKGROUND

Acne is a common skin disease that mostly affects teenagers, with a negative impact on quality of life. Recently, adult acne and acne relapses have increased in frequency, for yet unknown reasons.

OBJECTIVE

This non-interventional, real-life study sought to investigate the rate of acne relapses and their impact on quality of life and productivity (loss/absenteeism) among teenagers and adults.

METHODS

An online self-administered questionnaire was proposed to ≥15-year-olds suffering from acne who spontaneously consulted their dermatologist. To ensure homogeneous assessment of acne severity, the global acne severity scale was applied. Quality of life was assessed via Cardiff Acne Disability Index (CADI), SF12-physical score and SF12-mental score questionnaires. Productivity loss or absenteeism in middle/high school was estimated based on the number of days off work or school over the last 30 days.

RESULTS

Overall, 1048 questionnaires were considered assessable, with 448 (43%) mild acne, 434 (41%) moderate acne and 166 (16%) severe acne. Overall, 755 (72%) participants were in middle/high school, 267 (25%) employed and 26 (3%) with no professional activity. Considering the population by age groups, 68% (n = 716) were ≤20-year-olds and 32% (n = 332) >20-year-olds, with a mean age of 20.26 (SD: 7.43) years. Acne relapses were reported by 44% of respondents. Analyses revealed that poorer quality of life scores was observed in acne relapsers vs. non-relapsers, with a significant difference for CADI scores (P < 0.01) in >20-year-olds. Acne-related absenteeism was recorded in 5.7% of cases. On multivariate analyses, after adjusting for other variables, acne relapse was proven a significant determinant of absenteeism/productivity loss.

CONCLUSION

This real-life study first demonstrated acne relapse rates of 44%, which appeared to be generation-dependent, affecting 39.9% of ≤20-year-olds vs. 53.3% of >20-year-olds. Acne relapses were significantly associated with impaired quality of life and productivity loss/absenteeism.

[Study of the formation of N-glycolylmuramic acid from Nocardia asteroides (author's transl)]

Nocardia asteroides was grown in Sauton medium containing sodium [carboxy-14C]acetate. The biosynthesis of the peptidoglycan was inhibited by adding penicillin or phosphonomycin to the growth medium. These antibiotics give an accumulation of radioactive nucleotidic precursors of the peptidoglycan. In the presence of penicillin, there was an accumulation of uridine diphosphate-N-glycolylmuramyl peptide (UDP-MurNGlyc peptide) and of a mixture of uridine diphosphate-N-acetyl and N-glycolylmuramic acid (UDP-MurNAc) and UDP-MurNGlyc). In the presence of phosphonomycin, the biosynthesis of muramic acid was blocked and there was an accumulation of uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) and uridine diphosphate-N-glycolyglucosamine (UDP-GlcNGlyc). Thus the formation of a N-glycolyl group can be performed upon the neucleotidic derivatives of glucosamine and muramic acid. However in the peptidoglycan synthesized in vivo in the absence of antibiotic, only muramic acid was glycolyated. So, glycolylation seems to take place essentially on UDP-MurNAc. When the binding of peptide chain to muramic acid is achieved, all the muramic acid is glycolylated, then the polymerisation of glycan and peptidoglycan units by the mean of particulate enzymes is carried out on the N-glycolylated derivative of muramic acid. A cell-free preparation from Nocardia asteroides was obtained which can hydroxylate the acetyl group of UDP-MurNAc. The activity was localised in the soluble fraction. This system acts as a hydroxylase and requires the presence of NADPH.

Peptidoglycans synthesized by a membrane preparation of Micrococcus luteus

By incubation of cell-free particulate preparations from Micrococcus luteus with nucleotidic precursors uridine 5'-diphosphate-N-acetylglucosamine and uridine 5'-diphosphate-N-acetylmuramic acid-L-Ala-D-iso-Glu-L-Lys-D-Ala-D-Ala, several types of peptidoglycans were obtained: soluble peptidoglycan, insoluble peptidoglycan bound to the membrane and solubilized by trypsin, and peptidoglycan, which remained insoluble after the action of trypsin. The structure of each type of peptidoglycan was studied by action of lytic enzymes and separation of the fragments on Sephadex. Soluble peptidoglycans consist of a mixture of un-cross-linked polymers of various molecular weights. Trypsin-solubilized peptidoglycans are also a mixture of polymers of various sizes. They contain a preponderance of un-cross-linked material and some bridges with dimer peptides. Insoluble peptidoglycans, after the action of trypsin, contain about 50% of un-cross-linked peptide residues; in the other moiety, peptide units are cross-linked by D-Ala leads to L-Lys and D-Ala leads to L-Ala bonds which characterize the natural peptidoglycan. Therefore, the cell-free particulate preparation possesses the whole enzymatic system necessary for synthesis of cross-linked peptidoglycan.

Iodinated vancomycin and mucopeptide biosynthesis by cell-free preparations from Micrococcus lysodeikticus

A particulate preparation from Micrococcus lysodeikticus was used to synthesize cell-wall mucopeptide. Radioactive iodinated vancomycin became attached to the preparation simultaneously with a complete inhibition of mucopeptide synthesis. After mucopeptide synthesis had occurred in the absence of antibiotic, the preparation took up more vancomycin, suggesting that new binding sites terminating in acyl-d-alanyl-d-alanine had been produced. The mucopeptide product was divided into a soluble and an insoluble portion, both sensitive to lysozyme. The soluble portion did not combine with vancomycin and hence had presumably lost its terminal d-alanine residues, either by transpeptidation or because of carboxy-peptidase action. The synthesis of both portions was unaffected by the presence of penicillin, but the insoluble part showed increased affinity for vancomycin, thus indicating that penicillin had caused conservation of d-alanyl-d-alanine termini.

Evolution de la composition lipidique de Nocardia asteroides au cours de la croissance

By addition of 1-(14)C-sodium acedate to the growth medium of Nocardia asteroides, it can be shown that the lipid content increases during the exponential phase, but does not vary during the stationary phase of the growth. Nocardic acid biosynthesis from the medium molecular weight fatty acids occurs chiefly during te stationary phase. As these compounds are localised in the cell walls, it becomes evident that the lipid envelope of the walls is still increasing when the cell growth and division have stopped.