Molecular mechanisms of perilipin protein function in lipid droplet metabolism.

Perilipins are abundant lipid droplet (LD) proteins present in all metazoans and also in Amoebozoa and fungi. Humans express five perilipins, which share a similar domain organization: an amino-terminal PAT domain and an 11-mer repeat region, which can fold into amphipathic helices that interact with LDs, followed by a structured carboxy-terminal domain. Variations of this organization that arose during vertebrate evolution allow for functional specialization between perilipins in relation to the metabolic needs of different tissues. We discuss how different features of perilipins influence their interaction with LDs and their cellular targeting. PLIN1 and PLIN5 play a direct role in lipolysis by regulating the recruitment of lipases to LDs and LD interaction with mitochondria. Other perilipins, particularly PLIN2, appear to protect LDs from lipolysis, but the molecular mechanism is not clear. PLIN4 stands out with its long repetitive region, whereas PLIN3 is most widely expressed and is used as a nascent LD marker. Finally, we discuss the genetic variability in perilipins in connection with metabolic disease, prominent for PLIN1 and PLIN4, underlying the importance of understanding the molecular function of perilipins.

Clinical and genomic delineation of the new proximal 19p13.3 microduplication syndrome.

A small but growing body of scientific literature is emerging about clinical findings in patients with 19p13.3 microdeletion or duplication. Recently, a proximal 19p13.3 microduplication syndrome was described, associated with growth delay, microcephaly, psychomotor delay and dysmorphic features. The aim of our study was to better characterize the syndrome associated with duplications in the proximal 19p13.3 region (prox 19p13.3 dup), and to propose a comprehensive analysis of the underlying genomic mechanism. We report the largest cohort of patients with prox 19p13.3 dup through a collaborative study. We collected 24 new patients with terminal or interstitial 19p13.3 duplication characterized by array-based Comparative Genomic Hybridization (aCGH). We performed mapping, phenotype-genotype correlations analysis, critical region delineation and explored three-dimensional chromatin interactions by analyzing Topologically Associating Domains (TADs). We define a new 377 kb critical region (CR 1) in chr19: 3,116,922-3,494,377, GRCh37, different from the previously described critical region (CR 2). The new 377 kb CR 1 includes a TAD boundary and two enhancers whose common target is PIAS4. We hypothesize that duplications of CR 1 are responsible for tridimensional structural abnormalities by TAD disruption and misregulation of genes essentials for the control of head circumference during development, by breaking down the interactions between enhancers and the corresponding targeted gene.

First step towards a consensus strategy for multi-locus diagnostic testing of imprinting disorders.

BACKGROUND: Imprinting disorders, which affect growth, development, metabolism and neoplasia risk, are caused by genetic or epigenetic changes to genes that are expressed from only one parental allele. Disease may result from changes in coding sequences, copy number changes, uniparental disomy or imprinting defects. Some imprinting disorders are clinically heterogeneous, some are associated with more than one imprinted locus, and some patients have alterations affecting multiple loci. Most imprinting disorders are diagnosed by stepwise analysis of gene dosage and methylation of single loci, but some laboratories assay a panel of loci associated with different imprinting disorders. We looked into the experience of several laboratories using single-locus and/or multi-locus diagnostic testing to explore how different testing strategies affect diagnostic outcomes and whether multi-locus testing has the potential to increase the diagnostic efficiency or reveal unforeseen diagnoses. RESULTS: We collected data from 11 laboratories in seven countries, involving 16,364 individuals and eight imprinting disorders. Among the 4721 individuals tested for the growth restriction disorder Silver-Russell syndrome, 731 had changes on chromosomes 7 and 11 classically associated with the disorder, but 115 had unexpected diagnoses that involved atypical molecular changes, imprinted loci on chromosomes other than 7 or 11 or multi-locus imprinting disorder. In a similar way, the molecular changes detected in Beckwith-Wiedemann syndrome and other imprinting disorders depended on the testing strategies employed by the different laboratories. CONCLUSIONS: Based on our findings, we discuss how multi-locus testing might optimise diagnosis for patients with classical and less familiar clinical imprinting disorders. Additionally, our compiled data reflect the daily life experiences of diagnostic laboratories, with a lower diagnostic yield than in clinically well-characterised cohorts, and illustrate the need for systematising clinical and molecular data.

Clinical Utility of a Unique Genome-Wide DNA Methylation Signature for KMT2A-Related Syndrome.

Wiedemann-Steiner syndrome (WDSTS) is a Mendelian syndromic intellectual disability (ID) condition associated with hypertrichosis cubiti, short stature, and characteristic facies caused by pathogenic variants in the KMT2A gene. Clinical features can be inconclusive in mild and unusual WDSTS presentations with variable ID (mild to severe), facies (typical or not) and other associated malformations (bone, cerebral, renal, cardiac and ophthalmological anomalies). Interpretation and classification of rare KMT2A variants can be challenging. A genome-wide DNA methylation episignature for KMT2A-related syndrome could allow functional classification of variants and provide insights into the pathophysiology of WDSTS. Therefore, we assessed genome-wide DNA methylation profiles in a cohort of 60 patients with clinical diagnosis for WDSTS or Kabuki and identified a unique highly sensitive and specific DNA methylation episignature as a molecular biomarker of WDSTS. WDSTS episignature enabled classification of variants of uncertain significance in the KMT2A gene as well as confirmation of diagnosis in patients with clinical presentation of WDSTS without known genetic variants. The changes in the methylation profile resulting from KMT2A mutations involve global reduction in methylation in various genes, including homeobox gene promoters. These findings provide novel insights into the molecular etiology of WDSTS and explain the broad phenotypic spectrum of the disease.

A recurrent RYR1 mutation associated with early-onset hypotonia and benign disease course.

The ryanodine receptor RyR1 is the main sarcoplasmic reticulum Ca2+ channel in skeletal muscle and acts as a connecting link between electrical stimulation and Ca2+-dependent muscle contraction. Abnormal RyR1 activity compromises normal muscle function and results in various human disorders including malignant hyperthermia, central core disease, and centronuclear myopathy. However, RYR1 is one of the largest genes of the human genome and accumulates numerous missense variants of uncertain significance (VUS), precluding an efficient molecular diagnosis for many patients and families. Here we describe a recurrent RYR1 mutation previously classified as VUS, and we provide clinical, histological, and genetic data supporting its pathogenicity. The heterozygous c.12083C>T (p.Ser4028Leu) mutation was found in thirteen patients from nine unrelated congenital myopathy families with consistent clinical presentation, and either segregated with the disease in the dominant families or occurred de novo. The affected individuals essentially manifested neonatal or infancy-onset hypotonia, delayed motor milestones, and a benign disease course differing from classical RYR1-related muscle disorders. Muscle biopsies showed unspecific histological and ultrastructural findings, while RYR1-typical cores and internal nuclei were seen only in single patients. In conclusion, our data evidence the causality of the RYR1 c.12083C>T (p.Ser4028Leu) mutation in the development of an atypical congenital myopathy with gradually improving motor function over the first decades of life, and may direct molecular diagnosis for patients with comparable clinical presentation and unspecific histopathological features on the muscle biopsy.

Patients with PWS and related syndromes display differentially methylated regions involved in neurodevelopmental and nutritional trajectory.

BACKGROUND: Prader-Willi syndrome is a rare genetic neurodevelopmental disorder caused by a paternal deficiency of maternally imprinted gene expression located in the chromosome 15q11-q13 region. Previous studies have demonstrated that several classes of neurodevelopmental disorders can be attributed to either over- or under-expression of specific genes that may lead to impairments in neuronal generation, differentiation, maturation and growth. Epigenetic changes that modify gene expression have been highlighted in these disorders. One recent study focused on epigenetic analysis and compared patients with PWS with patients with other imprinting disorders. No study, however, has yet focused on epigenetics in patients with PWS specifically by comparing the mutations associated with this syndrome. OBJECTIVE: This study investigated the epigenetic modifications in patients with PWS and patients with PWS-related disorders caused by inactivation of two genes of the PWS chromosomal region, SNORD116 and MAGEL2. Our approach also aimed to compare the epigenetic modifications in PWS and PWS-related disorders. METHODS: We compared genome-wide methylation analysis (GWAS) in seven blood samples from patients with PWS phenotype (five with deletions of the PWS locus, one with a microdeletion of SNORD116 and one with a frameshift mutation of MAGEL2 presenting with Schaaf-Yang syndrome), as well as two control patients. Controls were infants that had been studied for suspicion of genetic diseases that was not confirmed by the genetic analysis and the clinical follow-up. RESULTS: The analysis identified 29,234 differentially methylated cytosines, corresponding to 5,308 differentially methylated regions (DMRs), which matched with 2,280 genes. The DMRs in patients with PWS were associated with neurodevelopmental pathways, endocrine dysfunction and social and addictive processes consistent with the key features of the PWS phenotype. In addition, the separate analysis for the SNORD116 and MAGEL2 deletions revealed that the DMRs associated with the SNORD116 microdeletion were found in genes implicated in metabolic pathways and nervous system development, whereas MAGEL2 mutations mostly concerned genes involved in macromolecule biosynthesis. CONCLUSION: The PWS is associated with epigenetic modifications with differences in SNORD116 and MAGEL2 mutations, which seem to be relevant to the different associated phenotypes.

SNORD116 and growth hormone therapy impact IGFBP7 in Prader-Willi syndrome.

PURPOSE: Prader-Willi syndrome (PWS) is a neurodevelopmental disorder with hypothalamic dysfunction due to deficiency of imprinted genes located on the 15q11-q13 chromosome. Among them, the SNORD116 gene appears critical for the expression of the PWS phenotype. We aimed to clarify the role of SNORD116 in cellular and animal models with regard to growth hormone therapy (GHT), the main approved treatment for PWS. METHODS: We collected serum and induced pluripotent stem cells (iPSCs) from GH-treated PWS patients to differentiate into dopaminergic neurons, and in parallel used a Snord116 knockout mouse model. We analyzed the expression of factors potentially linked to GH responsiveness. RESULTS: We found elevated levels of circulating IGFBP7 in naive PWS patients, with IGFBP7 levels normalizing under GHT. We found elevated IGFBP7 levels in the brains of Snord116 knockout mice and in iPSC-derived neurons from a SNORD116-deleted PWS patient. High circulating levels of IGFBP7 in PWS patients may result from both increased IGFBP7 expression and decreased IGFBP7 cleavage, by downregulation of the proconvertase PC1. CONCLUSION: SNORD116 deletion affects IGFBP7 levels, while IGFBP7 decreases under GHT in PWS patients. Modulation of the IGFBP7 level, which interacts with IGF1, has implications in the pathophysiology and management of PWS under GHT.

Genetics of the congenital absence of the vas deferens.

Congenital absence of the vas deferens (CAVD) may have various clinical presentations depending on whether it is bilateral (CBAVD) or unilateral (CUAVD), complete or partial, and associated or not with other abnormalities of the male urogenital tract. CBAVD is usually discovered in adult men either during the systematic assessment of cystic fibrosis or other CFTR-related conditions, or during the exploration of isolated infertility with obstructive azoospermia. The prevalence of CAVDs in men is reported to be approximately 0.1%. However, this figure is probably underestimated, because unilateral forms of CAVD in asymptomatic fertile men are not usually diagnosed. The diagnosis of CAVDs is based on clinical, ultrasound, and sperm examinations. The majority of subjects with CAVD carry at least one cystic fibrosis-causing mutation that warrants CFTR testing and in case of a positive result, genetic counseling prior to conception. Approximately 2% of the cases of CAVD are hemizygous for a loss-of-function mutation in the ADGRG2 gene that may cause a familial form of X-linked infertility. However, despite this recent finding, 10-20% of CBAVDs and 60-70% of CUAVDs remain without a genetic diagnosis. An important proportion of these unexplained CAVDs coexist with a solitary kidney suggesting an early organogenesis disorder (Wolffian duct), unlike CAVDs related to CFTR or ADGRG2 mutations, which might be the result of progressive degeneration that begins later in fetal life and probably continues after birth. How the dysfunction of CFTR, ADGRG2, or other genes such as SLC29A3 leads to this involution is the subject of various pathophysiological hypotheses that are discussed in this review.

MINPP1 prevents intracellular accumulation of the chelator inositol hexakisphosphate and is mutated in Pontocerebellar Hypoplasia.

Inositol polyphosphates are vital metabolic and secondary messengers, involved in diverse cellular functions. Therefore, tight regulation of inositol polyphosphate metabolism is essential for proper cell physiology. Here, we describe an early-onset neurodegenerative syndrome caused by loss-of-function mutations in the multiple inositol-polyphosphate phosphatase 1 gene (MINPP1). Patients are found to have a distinct type of Pontocerebellar Hypoplasia with typical basal ganglia involvement on neuroimaging. We find that patient-derived and genome edited MINPP1-/- induced stem cells exhibit an inefficient neuronal differentiation combined with an increased cell death. MINPP1 deficiency results in an intracellular imbalance of the inositol polyphosphate metabolism. This metabolic defect is characterized by an accumulation of highly phosphorylated inositols, mostly inositol hexakisphosphate (IP6), detected in HEK293 cells, fibroblasts, iPSCs and differentiating neurons lacking MINPP1. In mutant cells, higher IP6 level is expected to be associated with an increased chelation of intracellular cations, such as iron or calcium, resulting in decreased levels of available ions. These data suggest the involvement of IP6-mediated chelation on Pontocerebellar Hypoplasia disease pathology and thereby highlight the critical role of MINPP1 in the regulation of human brain development and homeostasis.

Gingival Biopsy to Detect Mosaicism in Overgrowth Syndromes: Report of Two Cases of Megalencephaly-Capillary Malformation Syndrome with Periodontal Anomalies.

BACKGROUND: Megalencephaly-capillary malformation (MCAP) is a rare overgrowth syndrome caused by postzygotic activating mutations in the PIK3CA gene. AIM: To illustrate the benefits of gingival biopsy in the genetic diagnosis of overgrowth syndromes. DESIGN: Gingival biopsy was performed on a 13-year-old patient and a 16-year-old patient with MCAP and who suffered from periodontal disease. PIK3CA sequencing was performed on DNA extracted from gingival biopsies, blood, and saliva. RESULTS: Pathogenic p.Glu365Lys and p.Glu545Asp PIK3CA mutations were found in the gingival biopsies with an allelic frequency of 22% and 35%, respectively, while they were undetectable in blood or saliva. The genetic diagnosis of MCAP through detection of PIK3CA somatic mosaicism in a periodontal biopsy is unprecedented. CONCLUSIONS: Considering the tissue distribution and level of somatic mosaicism for PIK3CA mutation, the composite embryologic origin of periodontium and its high fibroblast cell content make it an ideal target for molecular analysis in overgrowth syndromes, and multidisciplinary approach including paediatric dentists should be encouraged. In addition, our clinical findings suggest that periodontal disease is part of the MCAP phenotypic spectrum and should be systematically investigated.

Chest pain in Brugada syndrome: Prevalence, correlations, and prognosis role.

BACKGROUND: Brugada syndrome (BrS) is sometimes diagnosed because of chest pain. Prevalence and characteristics of such BrS patients are unknown. METHODS: A total of 200 BrS probands were retrospectively included. BrS diagnosis made because of chest pain (n = 34, 17%) was compared to the other ones. RESULTS: BrS probands with diagnosis because of chest pain had significantly more often smoker habits, increased body mass index, and familial history of coronary artery disease but less frequently previous resuscitated sudden death/syncope or atrial fibrillation. Presence of coronary spasm and familial coronary artery disease were independently associated with BrS diagnosed because of chest pain. They presented more often with spontaneous type 1 ST elevation (59% vs 26%, P = .0004) and higher ST elevation during the episode of chest pain compared to other patients or compared to baseline electrocardiogram after chest pain resumption. ST elevation during chest pain was lower compared to ajmaline test. A total of 20% of them had significant coronary artery disease and four (11%) had coronary spasm, and they experienced more often recurrent chest pain episodes (24% vs 5%, P = .0002). Presence of chest pain at BrS diagnosis was not correlated to future arrhythmic events in univariate analysis. Only previous sudden cardiac death (SD)/syncope and familial SD were still significantly associated with outcome in multivariate analysis. CONCLUSION: Chest pain is a common cause for BrS diagnosis, although major part is not apparently explained by ischemic heart disease. Mechanisms leading to chest main remain unknown in the other ones. ST elevation is higher in this situation but does not seem to carry poor prognosis.

Novel ADGRG2 truncating variants in patients with X-linked congenital absence of vas deferens.

BACKGROUND: Congenital absence of vas deferens (CAVD) represents a major cause of obstructive azoospermia and is mainly related to biallelic alteration of the CFTR gene, also involved in cystic fibrosis. Using whole exome sequencing, we recently identified hemizygous loss-of-function mutations in the Adhesion G Protein-coupled Receptor G2 gene (ADGRG2) as responsible of isolated CAVD in the absence of associated unilateral renal agenesis. OBJECTIVES: The objective of this study was to retrospectively perform ADGRG2 sequencing on a large cohort of patients with CAVD, and 0 or only 1 CFTR defective allele identified after comprehensive testing in order to (a) define more precisely the spectrum and the frequency of ADGRG2 mutations within Caucasian population (b) explore the possibility of co-occurrence of CFTR and ADGRG2 mutations. MATERIALS AND METHODS: We collected 53 DNA samples from CAVD patients with 0 (n = 23) or 1 (n = 30) alteration identified after comprehensive CFTR testing in order to perform ADGRG2 sequencing. Twenty patients had normal ultrasonographic renal examination, and renal status was not documented for 33 patients. RESULTS: We identified six new truncating ADGRG2 mutations in 8 patients including two twin brothers: c.251C > G (p.Ser84*), c.1013delC (p.Pro338Hisfs*4), c.1460delG (p.Gly487Alafs*9), c.2096dupT (p.Phe700Ilefs*29), c.2473C > T (p.Arg825*), and c.1731_1839 + 373del (p.Asn578Thrfs*12), which is a 596 base pair deletion affecting the last five bases of exon 21 and the whole exon 22. Five of the eight patients also harbored an heterozygous CFTR mutation which we consider as incidental regarding the high penetrance expected for ADGRG2 truncating variants. The frequency of ADGRG2 truncating mutation was 26% (5/19 unrelated patients) when presence of both kidneys was attested by ultrasonography and 6.1% (2/33) among patients with unknown renal status. DISCUSSION & CONCLUSION: Our results confirm the interest of ADGRG2 sequencing in patients with CAVD not formerly related to CFTR dysfunction, especially in the absence of associated unilateral renal agenesis.

Male partners of infertile couples with congenital unilateral absence of the vas deferens are mainly non-azoospermic.

BACKGROUND: Men with congenital unilateral absence of vas deferens were reported to be mainly azoospermic, with both unilateral renal absence and mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) but some have neither. OBJECTIVES: To assess whether in infertile couples the male partners with congenital unilateral absence of vas deferens are mainly azoospermic men. MATERIAL AND METHODS: Retrospective study in a unique university hospital; reproductive, clinical, CFTR analysis and seminal data of male partners of infertile couples (from 1998 to 2018) were analysed. Diagnosis of congenital unilateral absence of vas deferens was based on transrectal ultrasounds (TRUS): complete or partial absence of one vas deferens with complete contralateral vas deferens confirmed in 63 men. Distribution of sperm count in three classes: azoospermia, oligozoospermia or normozoospermia. Ultrasound determination of renal status; seminal biomarkers assays; and search for CFTR mutations. RESULTS: Among the 63 men, 39.7% displayed azoospermia, 27% oligozoospermia and 33.3% normozoospermia; 42% of the non-azoospermic men (16/38) had previously obtained a natural pregnancy. We found unilateral renal absence in 17/59 patients (29%). Among 50 men with CFTR testing, five carried an allele associated with cystic fibrosis belonging to the 29 men without renal anomalies, indicating a high allelic frequency (8.6%). The 63 patients displayed high rates of surgical histories for undescended testicles or inguinal hernia, low values of semen volume and of total seminal glycerophosphocholine. CONCLUSIONS: Our results indicate that men with congenital unilateral absence of vas deferens mainly display oligozoospermia or normozoospermia and that they were previously fertile. They clearly confirm, first, that CFTR testing is recommended in congenital unilateral absence of vas deferens men and it should be mandatory for those with normal kidneys; and, second, that TRUS is needed for the diagnosis of congenital unilateral absence of vas deferens. As congenital unilateral absence of vas deferens may be present whatever the sperm count, biological warnings are represented by semen volume and seminal epididymal markers and clinical warnings by surgical histories of undescended testes or inguinal hernia.

Pulmonary Alveolar Microlithiasis in Children Less than 5 Years of Age.

OBJECTIVE: To collect all published cases up to January 2019 of pulmonary alveolar microlithiasis (PAM) in patients age 5 years and under and to compare their characteristics with those of the 1022 cases in the most recent all-age cohort published in 2015. STUDY DESIGN: We identified 28 cases of PAM worldwide in children age 5 years and under, accounting for only 2%-3% of all cases. RESULTS: Children seem more frequently symptomatic, notably with more cough and severe acute respiratory failure, but had no reported extrapulmonary manifestation. Children with PAM evidenced less typical radiologic findings, with frequent ground glass opacities not reported in adult cases and milder calcifications as less frequent, smaller, and mainly restricted to the lower lobes. CONCLUSIONS: PAM remains an uncommon diagnosis in young children, as symptoms and radiologic findings are less specific. Physicians should be aware to look for calcifications in chest computed tomography at mediastinal window and avoid elution of the bronchoalveolar lavage to find microliths. Collecting longitudinal data through an international registry would help in characterizing PAM to predict disease progression and plan lung transplantation.

Hearing loss in inherited peripheral neuropathies: Molecular diagnosis by NGS in a French series.

BACKGROUND: The most common inherited peripheral neuropathy is Charcot-Marie-Tooth disease (CMT), with a prevalence of 1/2500. Other symptoms can be associated to the condition, such as hearing loss. Currently, no global hearing impairment assessment has been determined, and the physiopathology is not well known. METHODS: The aim of the study was to analyze among a French series of 3,412 patients with inherited peripheral neuropathy (IPN), the ones who also suffer from hearing loss, to establish phenotype-genotype correlations. An NGS strategy for IPN one side and nonsyndromic hearing loss (NSHL) on the other side, were performed. RESULTS: Hearing loss (HL) was present in only 44 patients (1.30%). The clinical data of 27 patients were usable. Demyelinating neuropathy was diagnosed in 15 cases and axonal neuropathy in 12 cases. HL varied from mild to profound. Five cases of auditory neuropathy were noticed. Diagnosis was made for 60% of these patients. Seven novel pathogenic variants were discovered in five different genes: PRPS1; MPZ; SH3TC2; NEFL; and ABHD12. Two patients with PMP22 variant, had also an additional variant in COCH and MYH14 respectively. No pathogenic variant was found at the DFNB1 locus. Genotype-phenotype correlations do exist, especially with SH3TC2, PRPS1, ABHD12, NEFL, and TRPV4. CONCLUSION: Involvement of PMP22 is not enough to explain hearing loss in patients suffering from IPN. HL can be due to cochlear impairment and/or auditory nerve dysfunction. HL is certainly underdiagnosed, and should be evaluated in every patient suffering from IPN.

New PRPS1 variant p.(Met68Leu) located in the dimerization area identified in a French CMTX5 patient.

BACKGROUND: CMTX5 is characterized by peripheral neuropathy, early-onset sensorineural hearing impairment, and optic neuropathy. Only seven variants have been reported and no genotype-phenotype correlations have yet been established. PRPS1 has a crystallographic structure, as it is composed of three dimers that constitute a hexamer. METHODS: Next-generation sequencing (NGS) was performed using a custom 92-gene panel designed for the diagnosis of Charcot-Marie-Tooth (CMT) and associated neuropathies. RESULTS: We report the case of a 35-year-old male, who had presented CMT and hearing loss since childhood associated to bilateral optic neuropathy without any sign of retinitis pigmentosa. A new hemizygous variant on chromosomic position X:106,882,604, in the PRPS1 gene, c.202A > T, p.(Met68Leu) was found. This change is predicted to lead to an altered affinity between the different subunits in the dimer, thereby may prevent the hexamer formation. CONCLUSION: CMTX5 is probably under-diagnosed, as an overlap among the different features due to PRPS1 exists. Patients who developed polyneuropathy associated to sensorineural deafness and optic atrophy during childhood should be assessed for PRPS1.

Development and Validation of a New Risk Prediction Score for Life-Threatening Ventricular Tachyarrhythmias in Laminopathies.

BACKGROUND: An accurate estimation of the risk of life-threatening (LT) ventricular tachyarrhythmia (VTA) in patients with LMNA mutations is crucial to select candidates for implantable cardioverter-defibrillator implantation. METHODS: We included 839 adult patients with LMNA mutations, including 660 from a French nationwide registry in the development sample, and 179 from other countries, referred to 5 tertiary centers for cardiomyopathies, in the validation sample. LTVTA was defined as (1) sudden cardiac death or (2) implantable cardioverter defibrillator-treated or hemodynamically unstable VTA. The prognostic model was derived using the Fine-Gray regression model. The net reclassification was compared with current clinical practice guidelines. The results are presented as means (SD) or medians [interquartile range]. RESULTS: We included 444 patients, 40.6 (14.1) years of age, in the derivation sample and 145 patients, 38.2 (15.0) years, in the validation sample, of whom 86 (19.3%) and 34 (23.4%) experienced LTVTA over 3.6 [1.0-7.2] and 5.1 [2.0-9.3] years of follow-up, respectively. Predictors of LTVTA in the derivation sample were: male sex, nonmissense LMNA mutation, first degree and higher atrioventricular block, nonsustained ventricular tachycardia, and left ventricular ejection fraction (https://lmna-risk-vta.fr). In the derivation sample, C-index (95% CI) of the model was 0.776 (0.711-0.842), and the calibration slope 0.827. In the external validation sample, the C-index was 0.800 (0.642-0.959), and the calibration slope was 1.082 (95% CI, 0.643-1.522). A 5-year estimated risk threshold ≥7% predicted 96.2% of LTVTA and net reclassified 28.8% of patients with LTVTA in comparison with the guidelines-based approach. CONCLUSIONS: In comparison with the current standard of care, this risk prediction model for LTVTA in laminopathies significantly facilitated the choice of candidates for implantable cardioverter defibrillators. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03058185.

Spinal muscular atrophy with respiratory distress type 1: A multicenter retrospective study.

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive neuromuscular disorder characterized by progressive motor and respiratory decline during the first year of life. Early and late-onset cases have recently been reported, although not meeting the established diagnostic criteria, these cases have been genotyped. We thus conducted a national multicenter observational retrospective study to determine the prognosis of children with SMARD1 according to their phenotype. We recorded all known French pediatric cases with mutations identified on the immunoglobulin µ-binding protein 2 gene and the presence of respiratory symptoms. Thirty centers provided 22 observations. A diaphragmatic palsy was diagnosed 1.5 months (p = 0.02) after first respiratory symptoms, and hypotonia preceded areflexia by 4 months (p = 0.02). Early onset of symptoms leading to specialist consultation before the age of 3 months was associated with a significantly worse prognosis (p < 0.01). Among the 6 patients who were still alive, all were tracheostomized. Only one case survived beyond 2 years without artificial ventilation. The remaining patients died at a median age of 7 months. Our results may help pediatricians to provide medical information to parents and improve the decision-making process of setting up life support.