ORAI1 inhibition as an efficient preclinical therapy for tubular aggregate myopathy and Stormorken syndrome

Tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK) are clinically overlapping disorders characterized by childhood-onset muscle weakness and a variable occurrence of multisystemic signs, including short stature, thrombocytopenia, and hyposplenism. TAM/STRMK is caused by gain-of-function mutations in the Ca2+ sensor STIM1 or the Ca2+ channel ORAI1, both of which regulate Ca2+ homeostasis through the ubiquitous store-operated Ca2+ entry (SOCE) mechanism. Functional experiments in cells have demonstrated that the TAM/STRMK mutations induce SOCE overactivation, resulting in excessive influx of extracellular Ca2+. There is currently no treatment for TAM/STRMK, but SOCE is amenable to manipulation. Here, we crossed Stim1R304W/+ mice harboring the most common TAM/STRMK mutation with Orai1R93W/+ mice carrying an ORAI1 mutation partially obstructing Ca2+ influx. Compared with Stim1R304W/+ littermates, Stim1R304W/+Orai1R93W/+ offspring showed a normalization of bone architecture, spleen histology, and muscle morphology; an increase of thrombocytes; and improved muscle contraction and relaxation kinetics. Accordingly, comparative RNA-Seq detected more than 1,200 dysregulated genes in Stim1R304W/+ muscle and revealed a major restoration of gene expression in Stim1R304W/+Orai1R93W/+ mice. Altogether, we provide physiological, morphological, functional, and molecular data highlighting the therapeutic potential of ORAI1 inhibition to rescue the multisystemic TAM/STRMK signs, and we identified myostatin as a promising biomarker for TAM/STRMK in humans and mice.

Modeling Glutaric Aciduria Type I in human neuroblastoma cells recapitulates neuronal damage that can be rescued by gene replacement

Glutaric Aciduria type I (GA1) is a rare neurometabolic disorder caused by mutations in the GDCH gene encoding for glutaryl-CoA dehydrogenase (GCDH) in the catabolic pathway of lysine, hydroxylysine and tryptophan. GCDH deficiency leads to increased concentrations of glutaric acid (GA) and 3-hydroxyglutaric acid (3-OHGA) in body fluids and tissues. These metabolites are the main triggers of brain damage. Mechanistic studies supporting neurotoxicity in mouse models have been conducted. However, the different vulnerability to some stressors between mouse and human brain cells reveals the need to have a reliable human neuronal model to study GA1 pathogenesis. In the present work we generated a GCDH knockout (KO) in the human neuroblastoma cell line SH-SY5Y by CRISPR/Cas9 technology. SH-SY5Y-GCDH KO cells accumulate GA, 3-OHGA, and glutarylcarnitine when exposed to lysine overload. GA or lysine treatment triggered neuronal damage in GCDH deficient cells. SH-SY5Y-GCDH KO cells also displayed features of GA1 pathogenesis such as increased oxidative stress vulnerability. Restoration of the GCDH activity by gene replacement rescued neuronal alterations. Thus, our findings provide a human neuronal cellular model of GA1 to study this disease and show the potential of gene therapy to rescue GCDH deficiency.

What can we learn from the platelet lipidome?

Besides their proteome, platelets use, in all responses to the environmental cues, a huge and diverse family of hydrophobic and amphipathic small molecules involved in structural, metabolic and signaling functions; the lipids. Studying how platelet lipidome changes modulate platelet function is an old story constantly renewed through the impressive technical advances allowing the discovery of new lipids, functions and metabolic pathways. Technical progress in analytical lipidomic profiling by top-of-the-line approaches such as nuclear magnetic resonance and gas chromatography or liquid chromatography coupled to mass spectrometry enables either large-scale analysis of lipids or targeted lipidomics. With the support of bioinformatics tools and databases, it is now possible to investigate thousands of lipids over a concentration range of several orders of magnitude. The lipidomic landscape of platelets is considered a treasure trove, not only able to expand our knowledge of platelet biology and pathologies but also to bring diagnostic and therapeutic opportunities. The aim of this commentary article is to summarize the advances in the field and to highlight what lipidomics can tell us about platelet biology and pathophysiology.

SARS-CoV-2 Omicron variant infection affects blood platelets, a comparative analysis with Delta variant

Introduction

In November 2021, the SARS-CoV-2 Omicron variant of concern has emerged and is currently dominating the COVID-19 pandemic over the world. Omicron displays a number of mutations, particularly in the spike protein, leading to specific characteristics including a higher potential for transmission. Although Omicron has caused a significant number of deaths worldwide, it generally induces less severe clinical signs compared to earlier variants. As its impact on blood platelets remains unknown, we investigated platelet behavior in severe patients infected with Omicron in comparison to Delta.

Methods

Clinical and biological characteristics of severe COVID-19 patients infected with the Omicron (n=9) or Delta (n=11) variants were analyzed. Using complementary methods such as flow cytometry, confocal imaging and electron microscopy, we examined platelet activation, responsiveness and phenotype, presence of virus in platelets and induction of selective autophagy. We also explored the direct effect of spike proteins from the Omicron or Delta variants on healthy platelet signaling.

Results

Severe Omicron variant infection resulted in platelet activation and partial desensitization, presence of the virus in platelets and selective autophagy response. The intraplatelet processing of Omicron viral cargo was different from Delta as evidenced by the distribution of spike protein-positive structures near the plasma membrane and the colocalization of spike and Rab7. Moreover, spike proteins from the Omicron or Delta variants alone activated signaling pathways in healthy platelets including phosphorylation of AKT, p38MAPK, LIMK and SPL76 with different kinetics.

Discussion

Although SARS-CoV-2 Omicron has different biological characteristics compared to prior variants, it leads to platelet activation and desensitization as previously observed with the Delta variant. Omicron is also found in platelets from severe patients where it induces selective autophagy, but the mechanisms of intraplatelet processing of Omicron cargo, as part of the innate response, differs from Delta, suggesting that mutations on spike protein modify virus to platelet interactions.

Immunohistologic Features of Cerebral Venous Thrombosis Due to Vaccine-Induced Immune Thrombotic Thrombocytopenia

OBJECTIVES

Vaccine-induced immune thrombotic thrombocytopenia (VITT), a recently described entity characterized by thrombosis at unusual locations such as cerebral venous sinus and splanchnic vein, has been rarely described after adenoviral-encoded COVID-19 vaccines. In this study, we report the immunohistological correlates in 3 fatal cases of cerebral venous thrombosis related to VITT analyzed at an academic medical center.

METHODS

Detailed neuropathologic studies were performed in 3 cases of cerebral venous thrombosis related to VITT after adenoviral COVID-19 vaccination.

RESULTS

Autopsy revealed extensive cerebral vein thrombosis in all 3 cases. Polarized thrombi were observed with a high density of neutrophils in the core and a low density in the tail. Endothelial cells adjacent to the thrombus were largely destroyed. Markers of neutrophil extracellular trap and complement activation were present at the border and within the cerebral vein thrombi. SARS-CoV-2 spike protein was detected within the thrombus and in the adjacent vessel wall.

DISCUSSION

Data indicate that neutrophils and complement activation associated with antispike immunity triggered by the vaccine is probably involved in the disease process.

Multicolor flow cytometry in clinical samples for platelet signaling assessment

Background

Availability of multichannel cytometers and specific commercial antibodies makes flow cytometry a new option to simultaneously assess multiple intracellular platelet signaling pathways for clinical purposes, in small volume of blood or low platelet count.

Objectives

To describe a multicolor flow cytometry with fluorescent barcoding technique for screening signaling pathways downstream membrane receptors of major platelet agonists (adenosine diphosphate, thrombin, thromboxane, and collagen).

Methods

By comparison with immunoblotting, we first selected the target phosphoproteins, AKT, P38MAPK, LIMK, and SPL76; the times of stimulation; and phosphoflow barcoding conditions. We then performed a clinical study on whole blood of patients without evidence of blood platelet disorder on standard biological screening, consulting for trivial or occasionally provoked bleeds without familial antecedent (bleeding of unknown origin, n = 23) or type-1 von Willebrand disease (n = 9). In addition, we included a small group of patients with definite platelet disorders (Glanzmann thrombasthenia, δ-storage pool deficiency, and immune glycoprotein VI-related disease with granule secretion defect).

Results

The range, kinetics, and distribution of fluorescence intensity were established for each agonist-target protein combination. Principal component analysis indicates a correlation in response to a target phosphoprotein (AKT and P38MAPK) to different agonists but no correlation in the response of different target phosphoproteins to the same agonist. The heterogeneity of individual responses in the whole population displayed was analyzed using clustering algorithm. Patients with platelet storage pool deficiency were positioned as lowest responders on the heatmap.

Conclusion

In complement of functional tests, this study introduces a new approach for rapid platelet signaling profiling in clinical practice.

AB0498 CONCENTRATIONS OF ADVANCED GLYCATION END PRODUCTS (AGEs) CORRELATE WITH INDEXES OF ACTIVITY AND DAMAGE ACCRUAL IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Background

It has been postulated that AGES could have a relevant role as inducers in the chronic inflammatory pathway present in various diseases1; among them, in immune-mediated diseases such as SLE, as well as that its concentration could be related to some parameters of the disease such as activity 2 or accumulated damage 3, showing studies discrepant results to date.

Objectives

To describe correlations between the concentrations of AGEs measured by cutaneous autofluorescence and various parameters related to the disease in a population of SLE patients.

Methods

AGE concentrations were measured by skin autofluorescence (Age Reader Mu Connect from Diagnoptics Technologies BV) in 66 SLE Caucasian patients and correlations with demographic and clinical data were analyzed, after adjusting for age, smoking and corticosteroids as possible confounding factors, according to previous data. Previous validation studies have shown that skin autofluorescence is strongly related to AGE levels in skin biopsies4. The indices were analyzed both as quantitative and categorized variables according to previously established categories or to medians/tertiles/quartiles depending on the distribution of the variable in our population.

Results

Table 1 shows some descriptive characteristics of our cohort. There were clinically and statistically significant differences in the values of AGEs according to the patient’s SLEDAI and SLICC. Specifically, it was observed that AGEs’ values in the population with severe activity according to SLEDAI was 0.61 (95% CI 0.85-2.046; p=0.045) points > than in those in remission (p=0.045); as well as AGEs‘ values in patients with SLICC ≥1 was 1.23 (95% CI 0.49-1.98; p=0.030) points > than in the group without cumulative damage. In all the models, the values of AGEs increased significantly with age, smoking and current treatment with corticosteroids, except for the model including the SLICC variable. Interactions in said model were explored, and it was observed that the concentration of AGES depended on the interaction between the value of SLICC and the intake of corticosteroids, so that differences were only observed between SLICC groups in those who took corticosteroids.

Table 1.

Descriptive characteristics of the cohort. c: categorized.

AverageSD%Age5415BMI25.364.68SmokerNo68.2Yes31.8AGEs2.60.7Disease duration (years)1611DAS282.221.16cDAS28remission71.2low9.1moderate15.2high4.5SLEDAI54cSLEDAIremission21.2low16.7moderate51.5high10.6SLICC11cSLICC00.0148.5>130.3321.2FACIT Fatigue Scale1810Patient global assessment (PGA)3.02.4cPGA0-131.82-328.8>339.4Physician global assessment1.71.3cPhysician global assessment0-147.0>153.0Visual Analogue Scale (VAS)3.13.1cVAS034.81-430.3>434.8Health Assessment Questionnaire (HAQ)0.5270.551cHAQ033.30-0.7536.4>0.7530.3CorticoidsYes27.3No72.7

Conclusion

A correlation with elevated values of AGEs was observed in those SLE patients with higher scores in the indexes of activity (SLEDAI) and damage accrual (SLICC). The fact that the differences in SLICC are only observed in those patients treated with corticosteroids suggests that, maybe, only the accumulated damage related to taking corticosteroids could be mediated by AGEs.

References

[1]Medzhitov R. Origin and physiological roles of inflammation. Nature 2008;454:428–435.

[2]Vytášek R, Šedová L, Vilím V. Increased concentration of two different advanced glycation end-products detected by enzyme immunoassays with new monoclonal antibodies in sera of patients with rheumatoid arthritis. BMC Musculoskelet Disord 2010;11:83.

[3]leeuw K de, Graaff R, Vries R de, Dullaart RP, Smit AJ, Kallenberg CG, Bijl M. Accumulation of advanced glycation endproducts in patients with systemic lupus erythematosus. Rheumatology 2007;46:1551–1556.

[4]Meerwaldt R, Links T, Graaff R, Thorpe SR, Baynes JW, Hartog J, Gans R, Smit A. Simple noninvasive measurement of skin autofluorescence. Ann N Y Acad Sci 2005;1043:290-298.

Disclosure of Interests

None declared

AB1460 ACCUMULATED ADVANCED GLYCATION ENDPRODUCTS ARE SIGNIFICANTLY HIGHER IN PATIENTS WITH IMMUNE-MEDIATED INFLAMMATORY DISEASES THAN IN HEALTHY POPULATION

Background

Advanced glycation endproducts (AGEs) are the result of non-enzymatic glycation of proteins, lipids or nucleic acids. In circumstances characterized by increased oxidative and carbonyl stress, such as chronic inflammation, AGEs can be formed more rapidly1, generating reactive oxygen species and activating inflammatory signaling cascades through their chief signaling receptor (commonly abbreviated as RAGE)2. This positive feedback of inflammation can play a role in the etiology of immune-mediated inflammatory diseases, more specifically in rheumatoid arthritis (RA), ankylosing spondylitis (AS) and systemic lupus erythematosus (SLE).

Objectives

To investigate whether the accumulated concentrations of AGEs in patients with SLE, RA or AS are significantly higher than in healthy patients.

Methods

One hundred thirteen consecutive patients fulfilling ACR/EULAR criteria for RA, 60 patients fulfilling ASAS/OMERACT MRI criteria for AS, 97 patients fulfilling ACR/SLICC criteria for SLE and 527 sex-matched healthy controls were recruited.in cross-sectional study. Exclusion criteria were pregnancy, diabetes mellitus, corticosteroid treatment ≥ 20mg/day and malignant neoplasm. Accumulated AGEs were non-invasively measured by skin autofluorescence (Age Reader Mu Connect, Diagnostics Technologies B.V) and demographic and clinical data were collected. AGEs comparisons between patients and controls were performed by multiple linear regression analysis adjusted by confunders, previously described in literature (age, smoking habit and cardiovascular risk-factors). Age was centered at 55 years.

Results

Table 1 shows some descriptive characteristics of our cohorts. AGEs adjusted mean was significantly increased in SLE patients compared with matched controls (95% CI [2.27, 2.76] vs [1.66, 1.89], p<0.0001), RA patients and controls (95% CI [2.41, 2.61] vs [1.68, 1.88], p<0.0001) and AS patients and controls (95% CI [2.03, 2.6] vs [1.66, 1.93], p<0.0001). In all 3 models, AGEs were also significantly positive correlated with smoking habit measured by packs per year (p<0.001) and age (p<0.0001).

Table 1.

Descriptive characteristics of the cohorts

SLERAASPatientsControlsPatientsControlsPatientsControlsN=96N=189N=113N=240N=60N=99AGEs2.57 (0.65)1.98 (0.45)2.59 (0.58)2.00 (0.42)2.26 (0.46)1.90 (0.46)Age51.0 [43.0;61.0]56.0 [52.0;62.0]58.0 [54.0;65.0]61.0 [56.0;66.0]47.5 [41.0;55.0]53.0 [49.0;57.0]SmokerNo76 (79.2%)133 (70.4%)86 (76.1%)196 (81.7%)42 (70.0%)58 (58.6%)Yes20 (20.8%)56 (29.6%)27 (23.9%)44 (18.3%)18 (30.0%)41 (41.4%)Packs/year0.00 [0.00;10.8]2.50 [0.00;18.8]2.50 [0.00;18.0]0.00 [0.00;12.6]0.00 [0.00;7.88]14.9 [2.00;30.6]HypertensionNo74 (77.1%)116 (61.4%)77 (68.1%)146 (60.8%)53 (88.3%)75 (75.8%)Yes22 (22.9%)73 (38.6%)36 (31.9%)94 (39.2%)7 (11.7%)24 (24.2%)ObesityNo80 (83.3%)128 (67.7%)86 (76.1%)163 (67.9%)51 (85.0%)81 (81.8%)Yes16 (16.7%)61 (32.3%)27 (23.9%)77 (32.1%)9 (15.0%)18 (18.2%)DyslipidemiaNo85 (88.5%)104 (55.0%)79 (69.9%)108 (45.0%)51 (85.0%)55 (55.6%)Yes11 (11.5%)85 (45.0%)34 (30.1%)132 (55.0%)9 (15.0%)44 (44.4%)

Continuous normal: mean (SD); Continuous non-normal: median [IQR]; Categorical: absolute (relative frequency)

Conclusion

Accumulated AGEs in all 3 pathologies are significantly higher than in the healthy controls. The different means of AGEs in each of the diseases, being higher in SLE and lower in AS, may suggest a different participation of AGEs in the immune-mediated mechanisms of each pathology.

References

[1]K. de Leeuw, R. Graaff et al., Accumulation of advanced glycation endproducts in patients with systemic lupus erythematosus, Rheumatology, Volume 46, Issue 10, October 2007, Pg 1551–1556.

[2]Yan S., Ramasamy R. & Schmidt A. Mechanisms of Disease: advanced glycation end-products and their receptor in inflammation and diabetes complications. Nat Rev Endocrinol4, 285–293 (2008).

Disclosure of Interests

None declared

AB0047 CARTILAGE DEGRADATION STATUS OF KNEE OSTEOARTHIRTIC PATIENTS CAN BE PREDICTED BY CHONDROCYTE GENE EXPRESSION ANALYSIS

Background

Osteoarthritis (OA) is the most common degenerative joint disease, but its pathogenesis is still poorly understood. OA is characterized by articular cartilage loss due to an imbalance in anabolic and catabolic gene expression of the chondrocyte, together with aberrant expression of transcription factors and inflammatory mediators.

Objectives

We aim to evaluate de genes implicated in the chondrocyte failure regarding the four issues assessed to evaluate cartilage integrity using Mankin score (MkS): surface integrity, cellularity, cell cloning and staining.

Methods

Knee OA (KOA) patients aged 60-75 undergoing a total knee replacement, were recruited. At surgery, tibial plateau and femur condyles were deposited in DMEM medium and sent to the laboratory within 4 hours of the extraction. Punches from areas located at low, medium and high load (1) were excised from each sample (approximately 11 areas per patient). For RNA analysis, punches were kept in RNAlater at -20ºC until analyzed. RNA extraction, cDNA synthesis and cDNA amplification of the selected genes were performed previous to gene expression quantifycation by OpenArray Assay with custom plates. ΔCt was analyzed by ExpressionSuite V1.3 using 6 housekeeping genes. For histology study, punchs were fixated in formalin and embedded in parafin. Sections of 4 µm were stained with hematoxilin eosin and Safranin O-Fast Green. Slices were scored using the modified MkS (2) by 3 independent observers. R (v3.3.2) analysis was used to explored the results with principal components analysis (PCA) and linear regression (LR).

Results

Surgical samples were obtained from a total of 27 patients and 219 different areas were analyzed. ΔCt of the 51 genes analyzed by PCA showed that 9 components were enough to represent >80% of variance of the model. The genes associated with each component are summarized in Table 1. LR shows that second and first component were significantly associated to all or most of the fields included in the MkS, respectively. In contrast, component 4, 5 and 9 were not associated with any field. Lower expression of genes represented in component 1 (mainly related with extracellular matrix content) are associated with higher MkS values. On the other hand, component 2 summarizes data of genes mainly related with factors regulating cell metabolism. In this case, higher expression of TNFαIP6, NGF, IGFBP1, CRLF1, TNFα, and lower expression of ACAN, COL11A2, COL2A1, COL10A1, SOX9 and TGFβ1, among others, are associated with increased MkS values.

Table 1.

Genes that most contribute (by order) to component 1 & 2 (due to space limitation). Data of LR analysis for each component and MkS item. Significant association marked in bold.

ComponentGenesMankin score item (β coefficient; p-value)Surface integrityCellularityCell cloningStaining1SERPINE2, COL8A2, OGN, COL5A, TIMP3, BMP6, CRLF1, TIMP2, WISP1, ST3GAL1, SERPINE1, TNFSF10, ASPN, NGF, CD44, TNFRSF11B, TGFA, ADAMTS5, COL15A1, LUM, TNFAIP6, PTGS2, BMP2-0.092; 0.006-0.025; 0.047-0.028; 0.078-0.043; 0.0152ACAN, GPC5, CFH, FGFR3, COL11A2, TGFB1, GREM1, TNFAIP6, NGF, SOX9, IGFBP1, MMP3, FGF2, CRLF1, TNFa, COL2A1, COL10A10.261; 2.54 10-70.050; 0.0100.066; 0.0050.072; 0.0073-0.174; 0.003-0.029; 0.191-0.076; 0.0060.004; 0.89840.068; 0.410-0.019; 0.543-0.055; 0.161-0.021; 0.6275-0.082; 0.3640.051; 0.1460.020; 0.644-0.052; 0.28360.050; 0.6050.023; 0.5480.111; 0.0170.062; 0.2287-0.120; 0.266-0.090; 0.0320.010; 0.839-0.113; 0.0528-0.134; 0.2740.006; 0.892-0.198; 0.001-0.131; 0.0479-0.220; 0.096-0.041; 0.425-0.101; 0.1100.020; 0.780

Conclusion

There is a correlation between the expression level of the studied genes and the MkS values, although the role played by each gene might be different according to the MkS issue evaluated. These results could be useful to describe biomarkers that identify burden of disease in KOA.

References

[1]Adouni M, Shirazi-Adl A. J Orthop Res. 2014 Jan;32(1):69-78.

[2]Moody HR, Heard BJ, et al. J Anat. 2012 Jul;221(1):47-54.

Acknowledgements

We acknowledge Berend Bremmen for his help in Mankin Score bibliography revision and image scoring.

Disclosure of Interests

None declared

Platelet Versus Megakaryocyte: Who Is the Real Bandleader of Thromboinflammation in Sepsis?

Platelets are mainly known for their key role in hemostasis and thrombosis. However, studies over the last two decades have shown their strong implication in mechanisms associated with inflammation, thrombosis, and the immune system in various neoplastic, inflammatory, autoimmune, and infectious diseases. During sepsis, platelets amplify the recruitment and activation of innate immune cells at the site of infection and contribute to the elimination of pathogens. In certain conditions, these mechanisms can lead to thromboinflammation resulting in severe organ dysfunction. Here, we discuss the interactions of platelets with leukocytes, neutrophil extracellular traps (NETs), and endothelial cells during sepsis. The intrinsic properties of platelets that generate an inflammatory signal through the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome are discussed. As an example of immunothrombosis, the implication of platelets in vaccine-induced immune thrombotic thrombocytopenia is documented. Finally, we discuss the role of megakaryocytes (MKs) in thromboinflammation and their adaptive responses.

Association between megakaryocyte abnormalities on bone marrow smear and response to thrombopoietin receptor agonists in adult patients with primary immune thrombocytopenia

Impaired platelet production is a mechanism of immune thrombocytopenia (ITP). Morphological abnormalities of megakaryocytes (MKs) are sometimes observed in this disease. Two studies have suggested an association between MK abnormalities and response to corticosteroids in primary ITP, but none have investigated this association for thrombopoietin-receptor agonists (TPO-RAs). This was the aim of this study. The source of population was the French CARMEN registry with prospective follow-up of adult patients with incident ITP. We included patients with primary ITP, treated by TPO-RA and with a bone marrow smear before initiating TPO-RA. MK abnormalities were categorized by the presence of dysplasia and by the stage of maturation. Among 451 patients screened, 38 were included in the analysis. There was no difference in the median percentage of dysplastic MKs between responders to TPO-RA (4.0%, 95% confidence interval - CI: 2.3-6.4) and non-responders (4.5%, 95% CI: 0.7-7.1). There was a slightly higher proportion of granular MKs (4.5%, 95% CI: 3-6) and basophilic MKs (30.1%, 95% CI: 21.9-39.1) in non-responders compared to responders (granular: 2.0%, 95% CI: 0-4.1; basophilic: 21.3%, 95% CI: 11.4-40.7). In conclusion, MK abnormalities were not associated with response achievement in ITP patients treated with TPO-RA in this series of 38 patients.

Systematic Screening for Deep Vein Thrombosis in Critically Ill Inpatients With COVID-19: Impact on the Incidence of Venous Thromboembolism

Background: Several studies suggest an increased incidence of thrombosis in COVID-19 patients. However, evidence on how to prevent and even treat it is scarce. The aim of this study was to compare the cumulative incidence of venous thromboembolism (VTE) of two different methods for lower extremity deep vein thrombosis (LE-DVT) diagnosis: systematic vs. clinically guided complete compression venous ultrasonography (CCUS). We conducted a monocentric, prospective, open-label, non-randomized study. All consecutive patients admitted in three intensive care units (ICUs) of University Hospital of Toulouse for COVID-19 pneumonia were included: one performed systematic screening for LE-DVT, the others did not. The primary outcome was the 21-day cumulative incidence of VTE. The secondary end points were the 21-day cumulative incidences of major bleeding and death.

Results: Among the 78 patients included, 27 (34.6%) underwent systematic screening for DVT 7 ± 2 days after ICU admission. Thirty-two patients (41.0%) were diagnosed with VTE, with a 21-day cumulative incidence of 42.3% (95% CI, 31.4–55.2), without difference between screened and non-screened patients (hazard ratio 1.45, 95% CI, 0.72–2.93). In the screened group, the frequency of isolated DVT was higher (25.9 vs. 5.9%, p-value = 0.027), but the frequency of pulmonary embolism was not reduced (25.9 vs. 29.4%, p-value = 0.745). The 21-day cumulative incidences of major bleeding and death were 9.6% (95% CI, 4.7–19.2) and 10.3% (95% CI, 5.0–20.8), respectively, without difference between the two groups.

Conclusions: A systematic screening for DVT in patients hospitalized in ICU was not associated with a higher diagnosis of VTE or a reduced diagnosis of PE.

Effects of novel Btk and Syk inhibitors on platelet functions alone and in combination in vitro and in vivo

BACKGROUND

Inhibitors of tyrosine kinases downstream of the B-cell receptor, such as Bruton's tyrosine kinase (Btk) or Spleen tyrosine kinase (Syk), used alone or in combination are new therapeutic options in the treatment of B-cell malignancies. A challenge in the development of second-generation Btk inhibitors is to limit their side effects such as the increased bleeding risk. Considering the pivotal role of Syk in immunoreceptor tyrosine-based activation motif mediated platelet signaling, the impact of inhibiting this kinase on platelet functions is also worth analyzing.

OBJECTIVES

We investigated the effect of a novel Btk inhibitor, tirabrutinib, and a Syk inhibitor, entospletinib, alone and in combination on platelet signaling and functions in vitro and ex vivo.

METHODS

Platelet aggregation, secretion, and signaling responses as well as thrombus growth under flow were analyzed in the presence of the inhibitors alone or in combination in vitro, at clinically relevant doses, and ex vivo in patients treated with these inhibitors in the context of a phase I trial.

RESULTS

Although tirabrutinib alone had modest effects on platelet activation in vitro and ex vivo, entospletinib alone efficiently inhibited washed platelet aggregation in response to collagen. However, entospletinib weakly affected platelet activation in platelet-rich plasma, in whole blood and ex vivo. Importantly, the combination of tirabrutinib and entospletinib induced a significant decrease in platelet response to collagen in vitro and ex vivo correlating with mild bleedings reported in some of the treated patients.

CONCLUSION

These new results should contribute to improve the safety of these targeted therapies.

Coagulation and heparin requirements during ablation in patients under oral anticoagulant drugs

BACKGROUND

Anticoagulation during catheter ablation should be closely monitored with activated clotting time (ACT). However vitamin K antagonists (VKA) or direct oral anticoagulant drugs (DOAC) may act differently on ACT and on heparin needs. The aim of this study was to compare ACT and heparin requirements during catheter ablation under various oral anticoagulant drugs and in controls.

METHODS

Sixty consecutive patients referred for ablation were retrospectively included: group I (n = 15, VKA), group 2 (n = 15, uninterrupted rivaroxaban), group 3 (n = 15, uninterrupted apixaban), and group 4 (n = 15, controls). Heparin requirements and ACT were compared throughout the procedure.

RESULTS

Heparin requirements during the procedure were significantly lower in patients under VKA compared to DOAC, but similar between DOAC patients and controls.Activated clotting time values were significantly higher in patients under VKA compared to DOAC and similar in DOAC patients versus controls. Furthermore, anticoagulation control as evaluated by the number/proportion of ACT> 300 as well as the time passed over 300 seconds was significantly better in patients under VKA versus DOAC, without significant differences between DOAC and controls. Finally, the number of patients/ACT with excessive ACT values was significantly higher in VKA versus DOAC patients versus controls.There was no significant difference between rivaroxaban and apixaban for ACT or heparin dosing throughout the procedure.

CONCLUSION

Vitamin K antagonists allowed less heparin requirement despite reaching higher ACT values and more efficient anticoagulation control (with more excessive values) compared to patients under DOAC therapy and to controls. There was no difference in heparin requirements or ACT between DOAC patients and controls.

Thromboembolic events and Covid-19

The novel Corona virus infection (Covid-19) first identified in China in December 2019 has rapidly progressed in pandemic leading to significant mortality and unprecedented challenge for healthcare systems. Although the clinical spectrum of Covid-19 is variable, acute respiratory failure and systemic coagulopathy are common in severe Covid-19 patients. Lung is an important target of the SARS-CoV-2 virus causing eventually acute respiratory distress syndrome associated to a thromboinflammatory state. The cytokinic storm, thromboinflammation and pulmonary tropism are the bedrock of tissue lesions responsible for acute respiratory failure and for prolonged infection that may lead to multiple organ failure and death. The thrombogenicity of this infectious disease is illustrated by the high frequency of thromboembolic events observed even in Covid-19 patients treated with anticoagulation. Increased D-Dimers, a biomarker reflecting activation of hemostasis and fibrinolysis, and low platelet count (thrombocytopenia) are associated with higher mortality in Covid-19 patients. In this review, we will summarize our current knowledge on the thromboembolic manifestations, the disturbed hemostatic parameters, and the thromboinflammatory conditions associated to Covid-19 and we will discuss the modalities of anticoagulant treatment or other potential antithrombotic options.

An incidental finding in newborn screening leading to the diagnosis of a patient with ECHS1 mutations

Short-chain enoyl-CoA hydratase (ECHS1) is a mitochondrial beta-oxidation enzyme involved in the metabolism of acyl-CoA fatty acid esters, as well as in valine metabolism. ECHS1 deficiency has multiple manifestations, including Leigh syndrome early at birth or in childhood with poor prognosis, to cutis laxa, exercise-induced dystonia and congenital lactic acidosis.

Here we describe the case of a newborn with mutations in ECHS1 that caught our attention after the incidental finding of 3-hydroxy-butyryl\3-hydroxy-isobutyryl\malonylcarnitine (C4OH\C3DC) and tiglylcarnitine (C5:1) on blood spot in the newborn screening (NBS) program. Diagnosis was suspected based on the analysis of organic acids on dried urine spot. A moderate increase of 2-methyl-2,3-dihydroxybutyric acid, was detected, which is a known marker of this disease. Exome analysis showed c.404A>G (p.Asn135Ser) mutation in homozygosis in the ECHS1 gene. The child was therefore admitted to the hospital. Initial examination showed little response to auditory stimuli and mild hypertonia of the extremities. Clinical deterioration was evident at 4 months of age, including neurological and cardiac involvement, and the patient died at 5 months of age. This case illustrates how an incidental detection in the NBS Program can lead to the diagnosis ECHS1 deficiency. Although it is a severe disease, with no treatment available, early detection would allow adequate genetic counseling avoiding the odyssey that suffered most of these families.

A statistical algorithm showing coenzyme Q10 and citrate synthase as biomarkers for mitochondrial respiratory chain enzyme activities

Laboratory data interpretation for the assessment of complex biological systems remains a great challenge, as occurs in mitochondrial function research studies. The classical biochemical data interpretation of patients versus reference values may be insufficient, and in fact the current classifications of mitochondrial patients are still done on basis of probability criteria. We have developed and applied a mathematic agglomerative algorithm to search for correlations among the different biochemical variables of the mitochondrial respiratory chain in order to identify populations displaying correlation coefficients >0.95. We demonstrated that coenzyme Q10 may be a better biomarker of mitochondrial respiratory chain enzyme activities than the citrate synthase activity. Furthermore, the application of this algorithm may be useful to re-classify mitochondrial patients or to explore associations among other biochemical variables from different biological systems.

Pilot Experience with an External Quality Assurance Scheme for Acylcarnitines in Plasma/Serum

The analysis of acylcarnitines (AC) in plasma/serum is established as a useful test for the biochemical diagnosis and the monitoring of treatment of organic acidurias and fatty acid oxidation defects. External quality assurance (EQA) for qualitative and quantitative AC is offered by ERNDIM and CDC in dried blood spots but not in plasma/serum samples. A pilot interlaboratory comparison between 14 European laboratories was performed over 3 years using serum/plasma samples from patients with an established diagnosis of an organic aciduria or fatty acid oxidation defect. Twenty-three different samples with a short clinical description were circulated. Participants were asked to specify the method used to analyze diagnostic AC, to give quantitative data for diagnostic AC with the corresponding reference values, possible diagnosis, and advice for further investigations.Although the reference and pathological concentrations of AC varied among laboratories, elevated marker AC for propionic acidemia, isovaleric acidemia, medium-chain acyl-CoA dehydrogenase, very long-chain acyl-CoA dehydrogenase, and multiple acyl-CoA dehydrogenase deficiencies were correctly identified by all participants allowing the diagnosis of these diseases. Conversely, the increased concentrations of dicarboxylic AC were not always identified, and therefore the correct diagnosis was not reach by some participants, as exemplified in cases of malonic aciduria and 3-hydroxy-3-methylglutaryl-CoA lyase deficiency. Misinterpretation occurred in those laboratories that used multiple-reaction monitoring acquisition mode, did not derivatize, or did not separate isomers. However, some of these laboratories suggested further analyses to clarify the diagnosis.This pilot experience highlights the importance of an EQA scheme for AC in plasma.

Rare Late-Onset Presentation of Glutaric Aciduria Type I in a 16-Year-Old Woman with a Novel GCDH Mutation

Glutaric acidemia type I (GA-I) is a treatable autosomal recessive disorder of lysine, hydroxylysine, and tryptophan metabolism caused by glutaryl-CoA dehydrogenase (GCDH) deficiency. Presentation and progression of disease are variable ranging from asymptomatic carrier state to catastrophic encephalopathy. GA-I usually presents before age 18 months, usually triggered by childhood infection, with mild or severe acute encephalopathy, striatal degeneration, and movement disorder, most often acute dystonia. At a presymptomatic stage diagnosis is suggested clinically by macrocephaly, radiologically by widened Sylvian fissures and biochemically by the presence of excess 3-hydroxyglutaric acid and glutaric acid in urine. Treatment consists of lysine-restricted diet and carnitine supplementation, specific diet restrictions, as well as symptomatic and anticatabolic treatment of intercurrent illness. Presymptomatic diagnosis and treatment are essential to prognosis. We report the case of 16-year-old macrocephalic female with late-onset GA-I and unusual paucisymptomatic presentation with fainting after exercise and widespread white matter signal changes at MRI. She was compound heterozygote for a novel mutation (IVS10-2A>G) affecting splicing at GCDH and a common missense mutation (c. 1240C>T; p.Arg402Trp, R402W). Interestingly, the site of the novel mutation is the nucleotide position of a common mutation found almost exclusively in patients of Chinese/Taiwanese origin (IVS10-2A>C).

Clinical and biochemical outcome after hydroxocobalamin dose escalation in a series of patients with cobalamin C deficiency

BACKGROUND

CblC deficiency produces a combination of methylmalonic aciduria (MMA) and homocystinuria (HCU), and is the most common error of cobalamin metabolism. Patients present a wide spectrum of symptoms, ranging from early severe multisystemic forms, to milder late-onset phenotypes. Cognitive and visual impairment are nearly constant. Hydroxocobalamin (OHCbl), betaine, folinic acid, levocarnitine and eventually dietary protein restriction are the main therapeutic approaches. Although early introduction of OHCbl is crucial, no standardized protocols regarding dose adaptation exist. No reports on long-term outcomes after high doses of this vitamin have been published.

METHODS

In this study five patients with CblC deficiency (early severe forms) were treated with high doses of OHCbl for 18 to 30months. Clinical examinations, neurological assessment, and biochemical studies (plasma total homocysteine (tHcy), amino acids, hydroxocobalamin, and methylmalonic acid in urine) were periodically performed.

RESULTS

Variable clinical and biochemical outcomes were observed in patients treated with high doses of OHCbl. The best biochemical response was observed in those children with the worse metabolic control. By contrast, those patients with a concentration of tHcy around 50μmol/l or less showed only minor changes. Clinically, a considerable improvement was observed in those patients with severe problems in communication, expressive language and behavior.

CONCLUSIONS

According to our study, high OHCbl doses in CblC deficiency could have a greater benefit in those children with a prior history of suboptimal metabolic control, and also in those with severe neurological phenotypes. More specifically, we observed improvements in communication skills and behavior. These results should encourage further prospective trials to determine the optimal OHCbl regimen and to generate protocols and guidelines in this rare disorder.

Analysis of coenzyme Q(10) in lymphocytes by HPLC-MS/MS

Coenzyme Q(10) (CoQ(10)) deficiency syndromes are potentially treatable disorders. Skeletal muscle is the most widely accepted tissue for their study, but sampling is an invasive procedure. Cultured skin fibroblasts seem to improve the biochemical diagnosis, but their growth requires a certain period of time. Our aim was to set up a minimally invasive, fast and reliable analytical procedure to measure CoQ(10) in lymphocytes, to prevent any delay in diagnosing primary CoQ(10) deficiency. HPLC-MS/MS analysis of CoQ(10) showed high sensitivity and specificity. The reference range was established in apparently healthy volunteers (n=33); the mean of CoQ(10) in lymphocytes was 107nmol/g protein (95% confidence interval: 105-120) and 2.0nmol/UCS (95% confidence interval: 2.06-2.46). Therefore, the range was narrower when normalized to units of citrate synthase (UCS) than when normalized to grams of protein. The method was linear from 0.01 to 1μM with a good precision and sensitivity (limit of quantification 0.01μM). Intra-assay and inter-assay coefficients of variation were lower than 13%. Recovery was higher than 95%. In our hands, lymphocytes seem to be a reliable matrix as they reflect intracellular content of CoQ(10). In addition, they can be obtained by a minimally invasive procedure (venipuncture).

Response to creatine analogs in fibroblasts and patients with creatine transporter deficiency

Creatine transporter (CRTR) deficiency is one of the most frequent causes of X-linked mental retardation. The lack of an effective treatment for this disease, in contrast to creatine (Cr) biosynthesis disorders that respond to Cr monohydrate (CM), led us to analyze the efficacy of a lipophilic molecule derived from Cr, creatine ethyl ester (CEE), in fibroblasts and patients with CRTR deficiency. CM and CEE uptake studies were performed in six controls and four fibroblast cell lines from patients. We found a significant increase in Cr uptake after 72 h of incubation with CEE (500 micromol/L) in patients and control fibroblasts compared to incubation with CM. Subsequently, we assayed the clinical effect of CEE administration in four patients with CRTR deficiency. After 1 year of treatment, a lack of significant improvement in neuropsychological assessment or changes in Cr level in brain (1)H MRS was observed, and CEE was discontinued. In conclusion, this 12-month trial with CEE did not increase the brain concentration of Cr. Our in vitro data lend support to the idea of a certain passive transport of CEE in both pathological and control cells, although more lipophilic molecules or other cell systems that mimic the BBB should be used for a better approach to the in vivo system.

Secondary disorders of glycosylation in inborn errors of fructose metabolism

Adamowicz and colleagues raised the alert in 2007 about patients with atypical hereditary fructose intolerance (HFI) primarily misdiagnosed as CDG Ix. We describe a girl with neonatal hypertonia, facial trismus, absent swallowing and coughing reflexes, gastro-oesophageal reflux and sporadically elevated Krebs cycle metabolites and lactate. At 14 months microcephaly and hepatomegaly were noted, with hypertransaminasaemia but normal blood coagulation, glucose, phosphate, and absent urinary reducing substances. Neurological impairment persisted. Because of hepatic and neurological abnormalities with developmental delay, Tf IEF was performed and showed a severe type 1 pattern, resulting in a wrong diagnosis of CDG. Subsequently, an aversion to fruits suggested HFI, confirmed by the finding of ALDOB mutations (p.A150P/p.N335K). The girl improved with fructose-free diet, but liver cirrhosis led to hepatic transplantation. She is now 7 years old with good evolution; facial trismus and hypertonia reversed, but microcephaly persists. Transferrin MALDI-TOF MS characterization revealed underoccupation of glycosylation sites and glycan abnormalities, which reversed with dietary treatment. High maternal fructose concentrations might have caused neonatal abnormalities. Although in our patient's mother there is no fructose accumulation at present, it is possible that increased ingestion of fruits and vegetables during pregnancy, together with her heterozygosity, caused an accumulation of fructose that finally affected the fetus. We also describe slightly abnormal transferrin isoelectric focusing and MALDI-TOF MS patterns of intact transferrin and N-glycans in a fructose-1,6-bisphosphatase (FBP1)-deficient patient. While HFI is a well-known cause of secondary CDG, we found no reports of abnormal transferrin isoelectric focusing patterns in FBP1 deficiency and we introduce this condition as a possible secondary cause for altered transferrin isoelectric focusing.

PDH E1β deficiency with novel mutations in two patients with Leigh syndrome

Most cases of pyruvate dehydrogenase complex (PDHc) deficiency are attributable to mutations in the PDHA1 gene which encodes the E(1)α subunit, with few cases of mutations in the genes for E(3), E3BP (E(3) binding protein), E(2) and E(1)-phosphatase being reported. Only seven patients with deficiency of the E(1)β subunit have been described, with mutations in the PDHB gene in six of them. Clinically they presented with a non-specific encephalomyopathy. We report two patients with new mutations in PDHB and Leigh syndrome. Patient 1 was a boy with neonatal onset of hyperlactataemia, corpus callosum hypoplasia and a convulsive encephalopathy. After neurological deterioration, he died at age 5 months. Autopsy revealed the characteristic features of Leigh syndrome. Patient 2, also a boy, presented a milder clinical course. First symptoms were noticed at age 16 months with muscular hypotonia, lactic acidosis and recurrent episodes of somnolence and transient tetraparesis. MRI revealed bilateral signal hyperintensities in the globus pallidus, midbrain and crura cerebri. PDHc and E(1) activities were deficient in fibroblasts in patient 1; in patient 2 PDHc deficiency was found in skeletal muscle. Mutations in PDHA1 were excluded. Sequencing of PDHB revealed a homozygous point mutation (c.302T>C), causing a predicted amino acid change (p.M101T) in patient 1. Patient 2 is compound heterozygote for mutations c.301A>G (p.M101V) and c.313G>A (p.R105Q). All three mutations appear to destabilize the E(1) enzyme with a decrease of both E(1)α and E(1)β subunits in immunoblot analysis. To our knowledge, these patients with novel PDHB mutations are the first reported with Leigh syndrome.

Creatine transporter deficiency in two adult patients with static encephalopathy

Creatine transporter deficiency is a recently identified X-linked inborn error of metabolism. The natural course of the disease is not well delineated since clinical data from adult patients have scarcely been reported. A progressive course of the disease has been noted in a few described cases. We report the first two Spanish adult patients with creatine transporter deficiency and compare their clinical phenotype and the evolution of the disease with those of other published cases. The two brothers were identified in a study of a cohort of 610 mentally handicapped male patients. The disease was detected by biochemical studies and confirmed by DNA studies. The most significant clinical features were mental retardation, epilepsy and autistic behaviour, and these symptoms did not worsen, in contrast to other reports. They did not present gastrointestinal problems or movement disorders. Creatine transporter deficiency could be an underdiagnosed metabolic disorder and should be considered in adult patients with mental retardation. Clinical presentation of this disorder showed marked differences among adult patients and the course of the disease was static in our cases. Detection of additional adult patients might allow better understanding of the phenotypic outcome at a later age.

Cervical length and gestational age at admission as predictors of intra-amniotic inflammation in preterm labor with intact membranes

OBJECTIVES

To evaluate cervical length and gestational age as predictors of intra-amniotic inflammation in patients admitted because of preterm labor and intact membranes.

METHODS

Ninety-three pregnant women with preterm labor and intact membranes were included in our study. Cervical length was measured on admission by transvaginal sonography and transabdominal amniocentesis was performed within the first 48 h following admission. Positive amniotic fluid cultures defined intra-amniotic infection. Levels of intra-amniotic interleukin-6 (IL-6) were measured, and a receiver-operating characteristics (ROC) curve was constructed to determine the best cut-off point of IL-6 for predicting intra-amniotic infection. This value was then used as a basis for determining a cut-off of IL-6 for defining intra-amniotic inflammation. Considering inflammatory status, perinatal outcomes were evaluated and compared. Logistic regression was used to investigate associations of different explanatory variables with inflammatory status. A non-invasive approach for detection of intra-amniotic inflammation in women admitted because of preterm labor with intact membranes was evaluated.

RESULTS

Intra-amniotic infection and inflammation rates were 14% and 28%, respectively. ROC curve analysis showed that the best cut-off value for IL-6 was 13.4 ng/mL for predicting intra-amniotic infection, which was comparable to the cut-off of 11.3 ng/mL reported previously by other authors (which we used to define inflammation). Regardless of the intra-amniotic microbial status, perinatal outcomes in women who developed intra-amniotic inflammation were worse than in those who did not. Cervical length < 15 mm and gestational age at admission < 28 weeks were independently associated with intra-amniotic inflammation. A strategy considering these two non-invasive parameters (either women admitted < 28 weeks or women admitted between >or= 28 and < 32 weeks with a cervical length < 15 mm) could detect 84.0% of women with intra-amniotic inflammation with a positive predictive value of 48.8%, providing improved diagnostic indices compared to either variable considered alone.

CONCLUSIONS

Cervical length and gestational age at admission can be used as a non-invasive method to assess the risk of intra-amniotic inflammation in preterm labor and intact membranes.

[L-2 hydroxyglutaric aciduria: presentation of a family diagnosed in adulthood]

Introduction. Organic acidurias are a group of hereditary metabolic disorders characterized by an increase in excretion of organic acids in urine. L-2 hydroxyglutaric aciduria is a neurodegenerative disorder with insidious onset after infancy, which is likely inherited in an autosomal recessive mode, characterized by mental retardation, progressive ataxia, epilepsy, macrocephaly, pyramidalism and extrapyramidal symptoms in variable combinations, with subcortical encephalopathy and cerebral atrophy in neuroimaging studies. Biochemical diagnosis was based on the detection of high levels of L-2 hydroxyglutaric acid in body fluids. Clinical case. We present the case of a 42 year old male patient with psychomotor development delay, generalized tonic epileptic crisis, and ataxia and pyramidal syndrome after the age of 18 months. Neuroimaging study findings revealed subcortical leukoencephalopathy. Diagnosis of the disease was reached after measuring the level of L-2 hydroxyglutaric acid in body fluid (blood, urine and cerebrospinal fluid). This diagnosis was also confirmed in three of the patient's brothers who were affected by a non-filial neurological disease by measurement of this acid level in urine. The genetic study was performed in all the cases. Discussion. As with the majority of patients who reach adulthood without having been diagnosed of this disease during infancy, we believe that this disorder should be considered as a possibility in adults presenting a combination of the symptoms described and subcortical encephalopathy in magnetic resonance imaging, regardless of whether there is a family background of it. Thus, it should be included in the differential diagnosis of leukodystrophy in adult patients.

Arginine supplementation in four patients with X-linked creatine transporter defect

BACKGROUND

Treatment with oral creatine monohydrate has not shown efficacy in patients with creatine transporter deficiency (CRTR-D). Another therapeutic option proposed is L-arginine, the substrate for the enzyme L-arginine:glycine amidinotransferase (AGAT). We evaluate clinical characteristics and cerebral creatine replenishment after L-arginine therapy in four patients with CRTR-D.

PATIENTS AND METHODS

Four boys with genetically confirmed diagnosis of CRTR-D (ages 9-16 years) were supplemented with L-arginine (0.4 g/kg per day) for a period of 9 months. Treatment efficacy was evaluated by clinical and neuropsychological assessment and determination of creatine signals by brain proton magnetic resonance spectroscopy ((1)H-MRS).

RESULTS

Epileptic seizures remained well controlled with antiepileptic drugs in three cases, both before and after L-arginine supplementation. Vineland Adaptive Behaviour Scale did not show any change in communication, daily living skills, socialization or motor skills, and a lack of improvement in brain (1)H-MRS follow-up was observed. L-Arginine was discontinued at the end of the observation period.

CONCLUSIONS

Nine months of L-arginine supplementation did not show effectiveness in the four patients affected with CRTR-D in this protocol.

Classic and late-onset neurological disease in two siblings with glutaryl-CoA dehydrogenase deficiency

Late-onset neurological disease has rarely been reported in patients with glutaryl-CoA dehydrogenase (GCDH) deficiency. We present two siblings with GCDH deficiency. One of them presented with the classic neurological disease (patient 1). Routine investigation of family members revealed that her apparently unharmed 13-year-old sister was also affected (patient 2). Patient 2 started to have academic difficulties in the months prior to our assessment. Her clinical examination was normal, with the exception of a cranial circumference of 57 cm (slightly over the 98 th centile). A severe leukoencephalopathy was demonstrated on MRI. Neuropsychological assessment showed an IQ within the normal-low range and a mild impairment of memory and executive function. Previous reports on late-onset neurological disease in GCDH deficiency have revealed that progressive leukoencephalopathy develops over time. Following the recently published guideline for the diagnosis and management of GCDH deficiency, both patients are receiving dietary treatment in combination with L-carnitine supplementation. We emphasize the need to search for chronic neurological changes of late-onset type in apparently unaffected GCDH deficiency cases diagnosed in routine family investigations.

[Glutaric aciduria type I. Clinical, biochemical and molecular findings in six patients in Venezuela]

INTRODUCTION

Glutaric aciduria type I is an autosomal recessive inborn error of metabolism that is due to a deficiency of the enzyme glutaryl-CoA dehydrogenase, which gives rise to an accumulation of glutaric and 3-hydroxyglutaric acids in biological fluids. Clinical features present as a sudden-onset severe neurological disorder, characterised by extrapyramidal signs (dystonia-dyskinesia), hypotonia, irritability, macrocephaly and degeneration of the basal ganglia; it may also manifest with unspecific symptoms, such as hypotonia and psychomotor retardation.

AIMS

To describe the clinical, biochemical, neuroimaging and molecular aspects in six Venezuelan patients and to highlight the importance of an early diagnosis of glutaric aciduria type I so as to be able to establish early treatment and thus prevent the neurological damage produced by this disease.

CASE REPORTS

Two patients were referred because of macrocephaly, hypotonia and psychomotor retardation, and four more following an encephalopathic crisis. In all of them, neuroimaging studies showed delays in myelination, bilateral frontotemporal hypoplasia and symmetric widening of the Sylvian fissures with poor opercularisation. Urinary organic acid analyses showed raised levels of glutaric and 3-hydroxyglutaric acids, and a molecular analysis confirmed the diagnosis.

CONCLUSIONS

Organic acid analysis should be indicated in all patients who present macrocephaly, hypotonia, psychomotor retardation or an encephalopathic crisis of unknown causation. This study allowed us to determine the behaviour of the disease in Venezuela, since no epidemiological data exist in the country.

[Cerebral creatine transporter deficiency: an infradiagnosed neurometabolic disease]

INTRODUCTION

Brain creatine deficiencies are a group of inborn errors of metabolism recently recognized which are caused by arginine: glycine amidinotransferase (AGAT) deficiency, guanidinoacetate metiltransferase (GAMT) deficiency and defects in creatine transporter (CRTR). Although all of them are characterized by a brain creatine deficiency, clinical and biochemical features are different.

CASE REPORTS

We present a retrospective study about four patients of masculine sex affected of creatine transporter defects who were recently diagnosed in our centre. We describe the clinical presentation features, the different tests that we used in the diagnosis process (brain magnetic resonance spectroscopy, biochemical analysis of guanidinoacetate and creatine/creatinine ratio in urine), evolution aspects and the response to treatment. The most significative clinical feature was developmental delay mainly in expressive speech, they also presented epilepsy (three cases), autism (three cases), hypotonia (one case) and microcephalia (one case). Brain magnetic resonance spectroscopy showed a low (three cases) or an absence (one case) of creatine level. To confirm the defect we studied the creatine uptake in fibroblasts and molecular analysis of the SLC6A8/creatine transporter gene. Patients with creatine transporter deficiency are being treated with arginine, because a lack of response to creatine.

CONCLUSION

Cerebral creatine transporter deficiency can present with different neurological symptoms but developmental and language delay and epilepsy are the most significative; diagnosis is easy and there are some therapeutical options.

Genetic analysis of the first 4 patients with beta-ureidopropionase deficiency

beta-Ureidopropionase is the third enzyme of the pyrimidine degradation pathway and it catalyses the irreversible hydrolysis of N-carbamyl-ss-aminoisobutyric acid or N-carbamyl-ss-alanine to beta-aminoisobutyric acid or ss-alanine, ammonia, and CO2. Analysis of the beta-ureidopropionase gene (UPB1) of the first 4 patients presenting with a complete enzyme deficiency, revealed the presence of 2 splice-site mutations (IVS1-2A>G and IVS8-1G>A) and one missense mutation (A85E). RT-PCR analysis of the complete beta-ureidopropionase cDNA suggested that both splice-site mutations lead to a variety of alternative splice variants, with deletions of a single or several exons. The alanine at position 85 was not conserved in other eukaryotic beta-ureidopropionase protein sequences.

[Diagnosis and treatment of brain creatine deficiency syndromes]

AIM

To review the clinical, biochemical and genetic aspects of brain creatine deficiency syndromes, as well as the therapeutic options available.

DEVELOPMENT

Brain creatine deficiency syndrome has recently been described as a series of inborn errors of metabolism that affect the synthesis and transport of creatine. Three metabolic defects are known: two affect synthesis -guanidinoacetate methyltransferase (GAMT) and arginine:glycine amidinotransferase (AGAT)- and one affects the transport of creatine. Clinically, these patients can display mental retardation, language disorders, epilepsy, autistic behaviour, neurological impairment and movement disorders. After the clinical selection, the different defects can be identified by a biochemical study involving the analysis of metabolites in biological fluids (guanidinoacetate and creatine/ creatinine ratio). Before continuing with the molecular studies, it is important to confirm the deficiency of brain creatine by means of magnetic resonance imaging with spectroscopy. Diagnostic confirmation of AGAT and GAMT deficits is carried out by determining the enzymatic activity in fibroblasts or lymphoblasts, or the incorporation of creatine in the case of studies of transport defects. The study of mutations in AGAT, GAMT (autosomal recessive inheritance) and SLC6A8 (X-linked) genes completes the diagnosis.

CONCLUSIONS

Brain creatine deficiency syndromes are mainly associated to mental retardation and autism. GAMT and AGAT deficiencies respond to treatment with creatine, whereas patients with transport defects do not respond to this therapy; new therapeutic approaches are therefore being evaluated for this disease.

X-Linked creatine transporter deficiency in two patients with severe mental retardation and autism

We describe the first two unrelated Spanish patients with creatine transporter deficiency initially identified by brain proton magnetic resonance spectroscopy (MRS). The clinical phenotype was characterized by severe mental retardation, epilepsy, autism, severe speech delay and absence of brain creatine by MRS. Urine creatine/creatinine ratio was increased and creatine uptake in fibroblasts was impaired in both patients. On DNA sequence analysis of the SLC6A8/creatine transporter gene, one hemizygous mutation was found in each patient: one mutation was novel and consisted of a deletion of two nucleotides c.878-879delTC in exon 5, resulting in a frameshift (p.Lys293fsX3), and in the other patient a known deletion of three nucleotides 1222-1224delTTC in exon 8 resulting in p.Phe408del. Creatine treatment for one year failed to improve the neurological symptoms and was associated with a striking increase in body weight in both patients (13 and 16 kg, respectively).

[In utero macrocephaly as clinical manifestation of glutaric aciduria type I. Report of a novel mutation]

INTRODUCTION

Macrocephaly is a pivotal clinical sign, associated with multiple neurological diseases, particularly neurometabolical ones, such as the glutaric aciduria type I (GA I). This aciduria resulting from the genetical deficiency of the enzyme glutaryl-CoA dehydrogenase (GCDH). Is a relatively common cause of acute metabolic brain damage in early childhood. We report on one case of GA I, with early manifestations since fetal period and a novel mutation.

CASE REPORT

Our patient was referred due macrocephaly in utero and occipitofrontal head circumference above the 98 percentile for chronologic age during first few months of life, hypotonia and development delay. The metabolic investigations of organic acids in urine and acylcarnitine profile in blood, the brain magnetic resonance and the molecular analyses of the glutaryl-CoA deshidrogenase gene, confirm the diagnosis. The molecular analysis allowed to identify one previously described mutation A293T and a novel mutation IVS5-2 A>G.

CONCLUSION

It is important the recognition of in utero macrocephaly as a sign to early diagnosis of glutaric aciduria type I to initiate specific therapy to prevent the encephalopathic crises and minimize brain damage in patients who are already neurologically impaired.

Correlation of genotype and phenotype in glutaryl-CoA dehydrogenase deficiency

We have investigated the correlation between genotype and phenotype in a large number of patients with glutaric aciduria type I (GA I). The deficiency of glutaryl-CoA dehydrogenase has been confirmed in the Rigshospitalet's laboratory in 215 patients since 1975. Most of the patients were of European ancestry. Complete absence of enzyme activity was found in more than half of the patients, while 34% of patients had a residual activity up to 5% and a few patients had a residual activity of 5-15%. In four exceptional cases, a very high residual activity of up to 30% was found. Enzyme studies are thus a reliable method for confirming the diagnosis of GA I, although it may be difficult to distinguish exceptional 'mild' cases from heterozygous carriers for GA I. Three of the patients with very high residual activity are compound heterozygous for the missense mutations R227P and V400M, both of which are associated with residual enzyme activity of 8-10% in homozygous patients. Patients with a mild mutation on at least one chromosome frequently show unusual biochemical findings such as low or normal urinary excretion of glutaric acid and mild or only slightly increased excretion of 3-hydroxyglutaric acid. In contrast, patients with severe mutations such as R402W or A293T on both alleles have no residual activity and show the typical urinary metabolite pattern. Clinical data were available for a subgroup of 79 patients. No correlation with the biochemical phenotype or the genotype could be established.

Characterization of human transferrin glycoforms by capillary electrophoresis and electrospray ionization mass spectrometry

Carbohydrate Deficient Glycoprotein Syndrome (CDGS) is an inherited metabolic disease affecting all parts of the body. The biochemical diagnosis of this syndrome is based on the presence of a special marker in blood, Carbohydrate Deficient Transferrin (CDT), which is also a marker of chronic alcohol abuse. CDT is characterized by abnormal glycoforms of serum transferrin (Tf). In the present study, electrophoretic separation of human serum transferrin glycoforms was carried out using a bare fused-silica capillary and the glycoforms present in commercial Tf were baseline separated. The limit of detection (LOD) of human Tf was around the nmol concentration range. The LOD of the trisialo- and disialo-Tf, expressed as percentages of the tetrasialo-Tf peak area, were 0.5% for trisialo-Tf and 0.4% for disialo-Tf, and these values were appropriate for CDGS diagnosis. Moreover, Tf glycoforms were characterized using mass spectrometry (MS). The method was applied to the analysis of normal and pathological serum samples, after dilution. The results obtained suggest a way of making a rapid and simple CDGS diagnosis.