Pubertal development of transfusion-dependent thalassemia patients in the era of oral chelation with deferasirox: results from the French registry.

Not available.

Perilipin 1: a systematic review on its functions on lipid metabolism and atherosclerosis in mice and humans.

The function of perilipin 1 in human metabolism was recently highlighted by the description of PLIN1 variants associated with various pathologies. These include severe familial partial lipodystrophy and early onset acute coronary syndrome. Additionally, certain variants have been reported to have a protective effect on cardiovascular diseases. The role of this protein remains controversial in mice and variant interpretation in humans is still conflicting. This literature review has two primary objectives (i) to clarify the function of the PLIN1 gene in lipid metabolism and atherosclerosis by examining functional studies performed in cells (adipocytes) and mice and (ii) to understand the impact of PLIN1 variants identified in humans based on the variant's location within the protein and the type of variant (missense or frameshift). To achieve these objectives, we conducted an extensive analysis of the relevant literature on perilipin 1, its function in cellular models and mice, and the consequences of its mutations in humans. We also utilized bioinformatics tools and consulted the Human Genetics Cardiovascular Disease Knowledge Portal to enhance the pathogenicity assessment of PLIN1 missense variants.

Episignatures in practice: independent evaluation of published episignatures for the molecular diagnostics of ten neurodevelopmental disorders.

Variants of uncertain significance (VUS) are a significant issue for the molecular diagnosis of rare diseases. The publication of episignatures as effective biomarkers of certain Mendelian neurodevelopmental disorders has raised hopes to help classify VUS. However, prediction abilities of most published episignatures have not been independently investigated yet, which is a prerequisite for an informed and rigorous use in a diagnostic setting. We generated DNA methylation data from 101 carriers of (likely) pathogenic variants in ten different genes, 57 VUS carriers, and 25 healthy controls. Combining published episignature information and new validation data with a k-nearest-neighbour classifier within a leave-one-out scheme, we provide unbiased specificity and sensitivity estimates for each of the signatures. Our procedure reached 100% specificity, but the sensitivities unexpectedly spanned a very large spectrum. While ATRX, DNMT3A, KMT2D, and NSD1 signatures displayed a 100% sensitivity, CREBBP-RSTS and one of the CHD8 signatures reached <40% sensitivity on our dataset. Remaining Cornelia de Lange syndrome, KMT2A, KDM5C and CHD7 signatures reached 70-100% sensitivity at best with unstable performances, suffering from heterogeneous methylation profiles among cases and rare discordant samples. Our results call for cautiousness and demonstrate that episignatures do not perform equally well. Some signatures are ready for confident use in a diagnostic setting. Yet, it is imperative to characterise the actual validity perimeter and interpretation of each episignature with the help of larger validation sample sizes and in a broader set of episignatures.

Enhanced cell viscosity: A new phenotype associated with lamin A/C alterations.

Lamin A/C is a well-established key contributor to nuclear stiffness and its role in nucleus mechanical properties has been extensively studied. However, its impact on whole-cell mechanics has been poorly addressed, particularly concerning measurable physical parameters. In this study, we combined microfluidic experiments with theoretical analyses to quantitatively estimate the whole-cell mechanical properties. This allowed us to characterize the mechanical changes induced in cells by lamin A/C alterations and prelamin A accumulation resulting from atazanavir treatment or lipodystrophy-associated LMNA R482W pathogenic variant. Our results reveal a distinctive increase in long-time viscosity as a signature of cells affected by lamin A/C alterations. Furthermore, they show that the whole-cell response to mechanical stress is driven not only by the nucleus but also by the nucleo-cytoskeleton links and the microtubule network. The enhanced cell viscosity assessed with our microfluidic assay could serve as a valuable diagnosis marker for lamin-related diseases.

Transfusion requirements and complication rate in ß-thalassemia intermedia due to heterozygous ß-globin gene mutation and triplicated α-globin genes.

INTRODUCTION: The heterozygous condition for ß-thalassemia mutation associated with an extra functional α-globin gene can produce a Thalassemia Intermedia (TI) phenotype. This genotype is the second in frequency in the French Thalassemia Registry NaThalY that prospectively collects laboratory and clinical data. MATERIALS AND METHODS: The present report analyses transfusion needs, iron overload (ferritin, hepatic and cardiac iron concentrations), and complication rates in 45 patients included in NaThalY and presenting a heterozygous ß0 or ß+ -thalassemia mutation associated with a triplication at HBA locus. This cohort was compared to a cohort of patients with TI due to mutations in the beta-globin gene only and included in the French registry. RESULTS: Patients with an extra functional α-globin gene showed a less severe anemia, lower transfusion needs and lower complication rates than those with TI related to the ß-globin gene only. Nevertheless, some of them displayed complications such as cholelithiasis or extramedullary hematopoiesis. In addition, one third of the cohort needed transfusions and another third was under iron chelation. CONCLUSION: The genotype associating a heterozygous ß0 or ß+ -thalassemia mutation with a triplication at HBA locus should be accurately diagnosed as it could lead to symptomatic anemia and to potential iron overload and iron-related complications even in patients with no transfusion need.

ß-Thalassemia in childhood: Current state of health in a high-income country.

ß-thalassemia is an haemoglobinopathy characterized by a defective synthesis of the ß-globin chain. To assess the current state of health of paediatric patients with ß-thalassemia, data from the French national registry regarding children born between 2005 and 2020 with ß-thalassemia intermedia (TI) or major (TM) were collected. A total of 237 patients (median age 7.1 years at last visit) were analysed, of whom 156 (65.8%) were born in France and 162 (68.4%) had a TM phenotype. The probability of survival for children with TM born in France was 98.3% at 15 years. Fifty-four (22.8%) children received a haematopoietic stem cell transplant with a success rate of 88.8%. Hepatic and cardiac iron overload monitoring in non-transplanted patients showed moderate overload in 15.7% (18/115) and 7.1% (7/99) of cases, respectively, while clinical complications were found in only 4 patients with TM (hepatic in 3 cases). At last visit, mean ferritinemia was 1293 ng/ml (±759). Overall, less than 10% of children underwent splenectomy. No significant impact of the disease on growth or academic achievement was observed. Deferasirox was the main first-line chelator, prescribed in 78.2% of cases, with side effects reported in 11.7% of instances.

Classification of red cell dynamics with convolutional and recurrent neural networks: a sickle cell disease case study.

The fraction of red blood cells adopting a specific motion under low shear flow is a promising inexpensive marker for monitoring the clinical status of patients with sickle cell disease. Its high-throughput measurement relies on the video analysis of thousands of cell motions for each blood sample to eliminate a large majority of unreliable samples (out of focus or overlapping cells) and discriminate between tank-treading and flipping motion, characterizing highly and poorly deformable cells respectively. Moreover, these videos are of different durations (from 6 to more than 100 frames). We present a two-stage end-to-end machine learning pipeline able to automatically classify cell motions in videos with a high class imbalance. By extending, comparing, and combining two state-of-the-art methods, a convolutional neural network (CNN) model and a recurrent CNN, we are able to automatically discard 97% of the unreliable cell sequences (first stage) and classify highly and poorly deformable red cell sequences with 97% accuracy and an F1-score of 0.94 (second stage). Dataset and codes are publicly released for the community.

Co-occurrence of oculocutaneous albinism type 2 and mild sickle cell disease explained by HbS/ßthal genotype in an individual from the Democratic Republic of Congo.

Oculocutaneous albinism type 2 (OCA2) is a pigmentation disorder characterized by hypopigmentation of the skin, hair and eyes and ocular features. Sickle cell disease (SCD) is caused either by homozygosity of the beta globin gene variant c.20A > T/p.Glu6Val giving rise to severe anemia or by combined abnormal hemoglobins (HbS/ßthal) leading to mild SCD. We report a 45 years old female patient from the Democratic Republic of Congo affected with these two disorders. She presented with creamy white skin and numerous pigmented patches called dendritic freckles, nystagmus, foveal hypoplasia grade 2, photophobia and very poor visual acuity. Sequencing of the OCA2 gene identified the common exon 7 deletion and a new pathogenic variant c.1444A > C/p.Thr482Pro. She had mild SCD with a total Hb level of 101 g/l. Hbß sequencing identified variants c.20A > T giving rise to HbS and c.315 + 1 G > A characteristic of ß-thalassemia. A heterozygous 3.7 kb deletion of the α globin gene was also found. The combined Hbß/α globin genotype explains the mild SCD phenotype. Co-occurrence of OCA2 and SCD raises the question whether the patient's phenotype simply results from the addition of the two diseases' phenotypes or whether interaction between the two diseases modulates the phenotype of each other.

Novel partial loss-of-function variants in the tyrosyl-tRNA synthetase 1 (YARS1) gene involved in multisystem disease.

Cytoplasmic aminoacyl-tRNA synthetases (ARSs) are emerging as a cause of numerous rare inherited diseases. Recently, biallelic variants in tyrosyl-tRNA synthetase 1 (YARS1) have been described in ten patients of three families with multi-systemic disease (failure to thrive, developmental delay, liver dysfunction, and lung cysts). Here, we report an additional subject with overlapping clinical findings, heterozygous for two novel variants in tyrosyl-tRNA synthetase 1 (NM_003680.3(YARS1):c.176T>C; p.(Ile59Thr) and NM_003680.3(YARS1):c.237C>G; p.(Tyr79*) identified by whole exome sequencing. The p.Ile59Thr variant is located in the highly conserved aminoacylation domain of the protein. Compared to subjects previously described, this patient presents a much more severe condition. Our findings support implication of two novel YARS1 variants in these disorders. Furthermore, we provide evidence for a reduced protein abundance in cells of the patient, in favor of a partial loss-of-function mechanism.

Genetic Enteropathies Linked to Epithelial Structural Abnormalities and Enteroendocrine Deficiency: A Systematic Review.

OBJECTIVES: Congenital diarrhea and enteropathies linked to epithelial structural abnormalities constitute 3 different rare diseases: the tufting enteropathies (TE; EPCAM and SPINT2 mutations), microvillous inclusion disease (MVID; MYO5B and STX3 mutations), and tricho-hepato-enteric syndrome (THE; TTC37 and SKIV2L mutations). Moreover, enteroendocrine deficiencies (ED; PCSK1 and NEUROG3 mutations) share common clinical characteristics with TE, THE, and MVID in that the treatment requires, in most cases, long-term parenteral nutrition. Although numerous cases have been reported in the literature, aggregated data on morbidity and mortality are missing owing to the rarity of the diseases. METHODS: We performed a systematic review of all published cases and retrieved 86 articles describing 323 patients (164 boys and 135 girls). RESULTS: The mortality rate was 20.28%, with a median age at death of 13.5 months (range 0-228 months); the mortality risk was 30.8/1000 person-year; in half of the cases, death was caused by infections. Parenteral nutrition was required in 95.4% of patients and weaning off from parenteral nutrition was achieved in 29.35% at a median age of 23 months (range 3.3-276 months). The patients with ED linked to PCSK1 were nearly all weaned at a median age of 14 months, but most of the patients became overweight. MVID patients with MYO5B mutations were most often born preterm. ED linked to NEUROG3 mutation and THE patients usually presented with intrauterine growth retardation. CONCLUSIONS: This review presents data from 323 patients with congenital diarrhea linked to EPCAM TE, SPINT2 TE, TTC37 THE, SKIV2L THE, MYO5B MVID, STX3 MVID, NEUROG3 ED, and PCSK1 ED mutations.

HbF-promoting polymorphisms may specifically reduce the residual risk of cerebral vasculopathy in SCA children with alpha-thalassemia.

Sickle cell anemia (SCA) is a disease characterized by abnormal red blood cell rheology. Because of their effects on HbS polymerization and red blood cell deformability, alpha-thalassemia and the residual HbF level are known genetic modifiers of the disease. The aim of our study was to determine if the number of HbF quantitative trait loci (QTL) would also favor a specific sub-phenotype of SCA as it is the case for alpha-thalassemia. Our results confirmed that alpha-thalassemia protected from cerebral vasculopathy but increased the risk for frequent painful vaso-occlusive crises. We also showed that more HbF-QTL may provide an additional and specific protection against cerebral vasculopathy but only for children with alpha-thalassemia (-α/αα or -α/-α genotypes).

A Rare Mutation in LMNB2 Associated with Lipodystrophy Drives Premature Cell Senescence.

Many proteins are causative for inherited partial lipodystrophies, including lamins, the essential constituents of the nuclear envelope scaffold called the lamina. By performing high throughput sequencing on a panel of genes involved in lipodystrophies, we identified a heterozygous mutation in LMNB2 gene (c.700C > T p.(Arg234Trp)) in a female patient presenting early onset type II diabetes, hypertriglyceridemia, and android fat distribution. This mutation is rare in the general population (frequency 0.013% in GnomAD) and was predicted pathogenic by a set of pathogenicity prediction software. Patient-derived fibroblasts showed nuclear shape abnormalities and premature senescence features, which are two typical cellular phenotypes associated with laminopathies. Moreover, we observed an atypical aggregation of lamin B2 in nucleoplasm, which co-distributes with emerin and lamin A/C, along with an abnormal distribution of lamin A/C at the nuclear envelope. Finally, reducing lamin B2 expression level by siRNA targeted toward LMNB2 transcripts resulted in decreased nuclear anomalies and senescence-associated beta-galactosidase, suggesting a role of the mutated protein in the occurrence of the observed cellular phenotype. Altogether, these results suggest that mutations in lamin B2 could produce premature senescence and partial lipodystrophy features as observed with certain mutants of lamin A/C.

Dynamics of Individual Red Blood Cells Under Shear Flow: A Way to Discriminate Deformability Alterations.

In this work, we compared the dynamics of motion in a linear shear flow of individual red blood cells (RBCs) from healthy and pathological donors (Sickle Cell Disease (SCD) or Sickle Cell-ß-thalassemia) and of low and high densities, in a suspending medium of higher viscosity. In these conditions, at lower shear rates, biconcave discocyte-shaped RBCs present an unsteady flip-flopping motion, where the cell axis of symmetry rotates in the shear plane, rocking to and fro between an orbital angle ±Ï• observed when the cell is on its edge. We show that the evolution of ϕ depends solely on RBC density for healthy RBCs, with denser RBCs displaying lower ϕ values than the lighter ones. Typically, at a shear stress of 0.08 Pa, ϕ has values of 82 and 72° for RBCs with average densities of 1.097 and 1.115, respectively. Surprisingly, we show that SCD RBCs display the same ϕ-evolution as healthy RBCs of same density, showing that the flip-flopping behavior is unaffected by the SCD pathology. When the shear stress is increased further (above 0.1 Pa), healthy RBCs start going through a transition to a fluid-like motion, called tank-treading, where the RBC has a quasi-constant orientation relatively to the flow and the membrane rotates around the center of mass of the cell. This transition occurs at higher shear stresses (above 0.2 Pa) for denser cells. This shift toward higher stresses is even more remarkable in the case of SCD RBCs, showing that the transition to the tank-treading regime is highly dependent on the SCD pathology. Indeed, at a shear stress of 0.2 Pa, for RBCs with a density of 1.097, 100% of healthy RBCs have transited to the tank-treading regime vs. less than 50% SCD RBCs. We correlate the observed differences in dynamics to the alterations of RBC mechanical properties with regard to density and SCD pathology reported in the literature. Our results suggest that it might be possible to develop simple non-invasive assays for diagnosis purpose based on the RBC motion in shear flow and relying on this millifluidic approach.

Molecular and Mechanobiological Pathways Related to the Physiopathology of FPLD2.

Laminopathies are rare and heterogeneous diseases affecting one to almost all tissues, as in Progeria, and sharing certain features such as metabolic disorders and a predisposition to atherosclerotic cardiovascular diseases. These two features are the main characteristics of the adipose tissue-specific laminopathy called familial partial lipodystrophy type 2 (FPLD2). The only gene that is involved in FPLD2 physiopathology is the LMNA gene, with at least 20 mutations that are considered pathogenic. LMNA encodes the type V intermediate filament lamin A/C, which is incorporated into the lamina meshwork lining the inner membrane of the nuclear envelope. Lamin A/C is involved in the regulation of cellular mechanical properties through the control of nuclear rigidity and deformability, gene modulation and chromatin organization. While recent studies have described new potential signaling pathways dependent on lamin A/C and associated with FPLD2 physiopathology, the whole picture of how the syndrome develops remains unknown. In this review, we summarize the signaling pathways involving lamin A/C that are associated with the progression of FPLD2. We also explore the links between alterations of the cellular mechanical properties and FPLD2 physiopathology. Finally, we introduce potential tools based on the exploration of cellular mechanical properties that could be redirected for FPLD2 diagnosis.

Three Mexican Families with ß thalassemia intermedia with different molecular basis.

Beta thalassemia (ß-thal) is a frequent monogenic disease, is clinically and molecularly heterogeneous. This study described molecular and laboratory findings for three Mexican patients with ß-thal intermedia phenotype and their relatives. Three Mexican families were studied for presenting ß-thal intermedia, ARMS-PCR and Gap-PCR were performed to screen for common mutations, Sanger sequencing for rare or new alleles, and MLPA for identifying deletions and or duplications. In all three families we observed, in heterozygote condition, the mutation c.118C > T (p.Gln39*) also known as codon 39(C > T) in the ß globin gene (HBB) associated with a novel molecular defect: a new duplication of the alpha globin gene cluster, a new deletion that includes the loss of exon 3 of HBB and finally a novel mutation in the 3'UTR of HBB (HBB: c.*132C > A). We report three Mexican families with beta thalassemia intermedia due to different molecular basis; a new single nucleotide mutation involving the last nucleotide of the ß-globin chain transcript; and two possible new DNA rearrangements, an α cluster duplication, and a partial ß gene deletion.

Unraveling LMNA Mutations in Metabolic Syndrome: Cellular Phenotype and Clinical Pitfalls.

This study details the clinical and cellular phenotypes associated with two missense heterozygous mutations in LMNA, c.1745G > T p.(Arg582Leu), and c.1892G> A p.(Gly631Asp), in two patients with early onset of diabetes mellitus, hypertriglyceridemia and non-alcoholic fatty liver disease. In these two patients, subcutaneous adipose tissue was persistent, at least on the abdomen, and the serum leptin level remained in the normal range. Cellular studies showed elevated nuclear anomalies, an accelerated senescence rate and a decrease of replication capacity in patient cells. In cellular models, the overexpression of mutated prelamin A phenocopied misshapen nuclei, while the partial reduction of lamin A expression in patient cells significantly improved nuclear morphology. Altogether, these results suggest a link between lamin A mutant expression and senescence associated phenotypes. Transcriptome analysis of the whole subcutaneous adipose tissue from the two patients and three controls, paired for age and sex using RNA sequencing, showed the up regulation of genes implicated in immunity and the down regulation of genes involved in development and cell differentiation in patient adipose tissue. Therefore, our results suggest that some mutations in LMNA are associated with severe metabolic phenotypes without subcutaneous lipoatrophy, and are associated with nuclear misshaping.

High prevalence of mutations in perilipin 1 in patients with precocious acute coronary syndrome.

BACKGROUND AND AIMS: Genetic partial lipodystrophies are rare heterogeneous disorders characterized by abnormalities of fat distribution and associated metabolic complications including a predisposition for atherosclerotic cardiovascular disease. We hypothesized that the milder forms of these diseases might be underdiagnosed and might result in early acute coronary syndrome (ACS) as the first sign of the pathology. METHODS: We performed targeted sequencing on a panel of 8 genes involved in genetic lipodystrophy for 62 patients with premature ACS, and selected heterozygous missense variations with low frequency. To confirm those results, we analyzed a second independent group of 60 additional patients through Sanger sequencing, and compared to a control group of 120 healthy patients. RESULTS: In the first cohort, only PLIN1 exhibited variants in more than 1 patient. In PLIN1, 3 different variants were found in 6 patients. We then analyzed PLIN1 sequence in the second cohort with premature ACS and found 2 other patients. Altogether, 8 patients were carriers of 4 different mutations in PLIN1. The variant frequencies in the total cohort of 122 patients were compared to frequencies observed in a local control cohort and in 2 different public databases showing a significant difference between patient vs control group frequencies for two mutations out of 4 (c.245C > T p = 10-4; c.839G > A p = 0.014). DISCUSSION: This is the first study that identifies a high frequency of potential pathogenic mutations in PLIN1 related to early onset ACS. These findings could contribute to the prevention and care of precocious ACS in families carrying those mutations.