Goal Attainment Scale in tinnitus (GAS-T): treatment goal priorities by chronic tinnitus patients in a real-world setting.

PURPOSE: Standard treatment for tinnitus is cognitive behavioral therapy, although level of evidence of effectiveness is low. There is need for a Goal Attainment Scale to evaluate treatment effects based on patient satisfaction. Preliminary work in a clinical sample has identified six common personal treatment goals. The purpose of this study is to determine whether the preliminary identified goals are confirmed by a heterogeneous sample of people with bothersome tinnitus and to identify any other common personal goals with the intention to construct a closed-end Goal Attainment Scale for tinnitus for use in research of effectiveness of (new) tinnitus treatments. METHODS: Two consecutive polls were plotted in an online peer support group form a heterogeneous sample. First, members were asked to vote for preliminary identified goals and asked to formulate additional personal goals. Corresponding goals were grouped together. Goals that were acknowledged by at least 10% of respondents were used in the second poll in which respondents could vote for statements that they recognized themselves in. RESULTS: The first poll (N = 180) resulted in 15 personal treatment goals. Comparison resulted in five common goals, which were confirmed in the second poll (N = 238): to gain control, to improve well-being and sleep, to reduce effects on hearing and to understand tinnitus. CONCLUSIONS: We expect that if a patient achieves personal goals, he will be likely to reduce healthcare consumption. Based on common personal goals, validity of treatment evaluations is increased. We present a closed-end Goal Attainment Scale in tinnitus.

Postauthorization safety study of betaine anhydrous.

Patient registries for rare diseases enable systematic data collection and can also be used to facilitate postauthorization safety studies (PASS) for orphan drugs. This study evaluates the PASS for betaine anhydrous (Cystadane), conducted as public private partnership (PPP) between the European network and registry for homocystinurias and methylation defects and the marketing authorization holder (MAH). Data were prospectively collected, 2013-2016, in a noninterventional, international, multicenter, registry study. Putative adverse and severe adverse events were reported to the MAH's pharmacovigilance. In total, 130 individuals with vitamin B6 nonresponsive (N = 54) and partially responsive (N = 7) cystathionine beta-synthase (CBS) deficiency, as well as 5,10-methylenetetrahydrofolate reductase (MTHFR; N = 21) deficiency and cobalamin C (N = 48) disease were included. Median (range) duration of treatment with betaine anhydrous was 6.8 (0-9.8) years. The prescribed betaine dose exceeded the recommended maximum (6 g/day) in 49% of individuals older than 10 years because of continued dose adaptation to weight; however, with disease-specific differences (minimum: 31% in B6 nonresponsive CBS deficiency, maximum: 67% in MTHFR deficiency). Despite dose escalation no new or potential risk was identified. Combined disease-specific treatment decreased mean ± SD total plasma homocysteine concentrations from 203 ± 116 to 81 ± 51 µmol/L (p < 0.0001), except in MTHFR deficiency. Recommendations for betaine anhydrous dosage were revised for individuals ≥ 10 years. PPPs between MAH and international scientific consortia can be considered a reliable model for implementing a PASS, reutilizing well-established structures and avoiding data duplication and fragmentation.

Time to Functional Recovery After Laser Tonsillotomy Performed Under Local Anesthesia vs Conventional Tonsillectomy With General Anesthesia Among Adults: A Randomized Clinical Trial.

Importance: Carbon dioxide laser tonsillotomy performed under local anesthesia may be an effective and less invasive alternative than dissection tonsillectomy for treatment of tonsil-related afflictions. Objective: To compare functional recovery and symptom relief among adults undergoing tonsillectomy or tonsillotomy. Design, Setting, and Participants: This randomized clinical trial was conducted at 5 secondary and tertiary hospitals in the Netherlands from January 2018 to December 2019. Participants were 199 adult patients with an indication for surgical tonsil removal randomly assigned to either the tonsillectomy or tonsillotomy group. Interventions: For tonsillotomy, the crypts of the palatine tonsil were evaporated using a carbon dioxide laser under local anesthesia, whereas tonsillectomy consisted of total tonsil removal performed under general anesthesia. Main Outcomes and Measures: The primary outcome was time to functional recovery measured within 2 weeks after surgery assessed for a modified intention-to-treat population. Secondary outcomes were time to return to work after surgery, resolution of primary symptoms, severity of remaining symptoms, surgical complications, postoperative pain and analgesics use, and overall patient satisfaction assessed for the intention-to-treat population. Results: Of 199 patients (139 [70%] female; mean [SD] age, 29 [9] years), 98 were randomly assigned to tonsillotomy and 101 were randomly assigned to tonsillectomy. Recovery within 2 weeks after surgery was significantly shorter after tonsillotomy than after tonsillectomy (hazard ratio for recovery after tonsillectomy vs tonsillotomy, 0.3; 95% CI, 0.2-0.5). Two weeks after surgery, 72 (77%) patients in the tonsillotomy group were fully recovered compared with 26 (57%) patients in the tonsillectomy group. Time until return to work within 2 weeks was also shorter after tonsillotomy (median [IQR], 4.5 [3.0-7.0] days vs 12.0 [9.0-14.0] days; hazard ratio for return after tonsillectomy vs tonsillotomy, 0.3; 95% CI, 0.2-0.4.). Postoperative hemorrhage occurred in 2 patients (2%) in the tonsillotomy group and 8 patients (12%) in the tonsillectomy group. At 6 months after surgery, fewer patients in the tonsillectomy group (25; 35%) than in the tonsillotomy group (54; 57%) experienced persistent symptoms (difference of 22%; 95% CI, 7%-37%). Most patients with persistent symptoms in both the tonsillotomy (32 of 54; 59%) and tonsillectomy (16 of 25; 64%) groups reported mild symptoms 6 months after surgery. Conclusions and Relevance: This randomized clinical trial found that compared with tonsillectomy performed under general anesthesia, laser tonsillotomy performed under local anesthesia had a significantly shorter and less painful recovery period. A higher percentage of patients had persistent symptoms after tonsillotomy, although the intensity of these symptoms was lower than before surgery. These results suggest that laser tonsillotomy performed under local anesthesia may be a feasible alternative to conventional tonsillectomy in this population. Trial Registration: Netherlands Trial Register Identifier: NL6866 (NTR7044).

Hydropic Ear Disease: Correlation Between Audiovestibular Symptoms, Endolymphatic Hydrops and Blood-Labyrinth Barrier Impairment.

Research Objective: To investigate the correlation between clinical features and MRI-confirmed endolymphatic hydrops (EH) and blood-labyrinth barrier (BLB) impairment. Study Design: Retrospective cross-sectional study. Setting: Vertigo referral center (Haga Teaching Hospital, The Hague, the Netherlands). Methods: We retrospectively analyzed all patients that underwent 4 h-delayed Gd-enhanced 3D FLAIR MRI at our institution from February 2017 to March 2019. Perilymphatic enhancement and the degree of cochlear and vestibular hydrops were assessed. The signal intensity ratio (SIR) was calculated by region of interest analysis. Correlations between MRI findings and clinical features were evaluated. Results: Two hundred and fifteen patients with MRI-proven endolymphatic hydrops (EH) were included (179 unilateral, 36 bilateral) with a mean age of 55.9 yrs and median disease duration of 4.3 yrs. Hydrops grade is significantly correlated with disease duration (P < 0.001), the severity of low- and high-frequency hearing loss (both P < 0.001), and the incidence of drop attacks (P = 0.001). Visually increased perilymphatic enhancement was present in 157 (87.7%) subjects with unilateral EH. SIR increases in correlation with hydrops grade (P < 0.001), but is not significantly correlated with the low or high Fletcher index (P = 0.344 and P = 0.178 respectively). No significant differences were found between the degree of EH or BLB impairment and vertigo, tinnitus or aural fullness. Conclusion: The degree of EH positively correlates with disease duration, hearing loss and the incidence of drop attacks. The BLB is impaired in association with EH grade, but without clear contribution to the severity of audiovestibular symptoms.

Effectiveness of endolymphatic duct blockage versus endolymphatic sac decompression in patients with intractable Ménière's disease: study protocol for a double-blinded, randomised controlled trial.

INTRODUCTION: Outcomes of surgery for Ménière's disease (MD) remain discordant. Recently, a new surgical procedure in which the endolymphatic duct is clipped was proposed. To date, only one prospective trial assessing this technique was published, yielding promising results. This protocol describes a prospective, double-blinded, randomised controlled trial that will be carried out to assess the effectiveness of this surgical intervention. METHODS: Eighty-four patients with intractable MD will be recruited from 13 hospitals in the Netherlands. Intraoperatively, randomisation will determine whether endolymphatic duct blockage (EDB) or endolymphatic sac decompression (ESD) will be performed. Randomisation will be 1:1 stratified for gender and duration of MD (recent-onset versus mature MD). All participants receive vestibular rehabilitation after surgery. Patients are followed up during 1 year after surgery. Follow-up visits will take place at 1 week, 3 months, 6 months and 12 months after surgery. The main study endpoint is proportion of patients who are free of vertigo spells at 12 months postoperatively. Secondary parameters include cumulative number of vertigo bouts, co-intervention, tinnitus, hearing, quality of life, cost effectiveness and a budget impact analysis. Total duration of the study is 4 years. ANALYSIS: The primary analysis will follow the intention-to-treat principle. For the primary outcome, a χ2 test will be performed. Secondary outcomes will be analysed using a linear mixed model (EDB versus decompression group) at the different time measurement point. ETHICS AND DISSEMINATION: This study was reviewed and approved by a board of specialists before funding was obtained, as well as by the Medical Research Ethics Committee Leiden-The Hague-Delft and the boards of all participating centres. Results of this study will be published in international peer-reviewed scientific journals and will be presented on (inter)national scientific conferences and meetings. TRIAL REGISTRATION NUMBERS: NL9095 and ISRCTN12074571; Pre-Results.

[Adenotonsillectomy with or without intubation? Safety of the adenotonsillectomy without endotracheal tube in children]. / Wel of geen intubatie bij adenotonsillectomie volgens Sluder?Resultaten.

OBJECTIVE: To determine the safety of the non-intubated and intubated adenotonsillectomy by the Sluder method in children DESIGN: Retrospective database study METHOD: We compared the data of adenotonsillectomy by the Sluder method in children until thirteen years of two teaching hospitals from 2014 until 2017. In the Amphia Hospital the procedure was performed without endotracheal tube placement and without perioperative opioids, in the Haga Hospital the patients were intubated and received perioperative opioids. Primary outcome was reoperation for postoperative haemorrhage. Secondary outcomes included desaturation (saturation ≤ 90% > 1 min), severe hypoxemia (saturation ≤ 85% for ≥ 5 min), airway complications, bradycardia, total postoperative haemorrhages, use of rescue medication, hospital readmission and 30-day mortality. RESULTS: A total of 1370 patients were analysed: 1267 adenotonsillectomies and 103 tonsillectomies. Median operation time was 7 minutes in the non-intubated group versus 12 minutes in the intubated group. The primary outcome occurred in thirteen patients in the group without intubation (2.2%) and eleven times in the group with intubation (1.4%). There was one case of severe hypoxemia in the group without intubation. Desaturation occurred mostly in the group without intubation (26.4%) for a short time (median 0 min, interquartile range 0-1). Bradycardia was seen more in the group with intubation (4.1% vs 2.2%). CONCLUSION: The incidence of postoperative haemorrhage and severe airway complications after adenotonsillectomy by the Sluder method with and without endotracheal tube placement in both groups was comparable.

Cystathionine ß-synthase deficiency in the E-HOD registry-part I: pyridoxine responsiveness as a determinant of biochemical and clinical phenotype at diagnosis.

Cystathionine ß-synthase (CBS) deficiency has a wide clinical spectrum, ranging from neurodevelopmental problems, lens dislocation and marfanoid features in early childhood to adult onset disease with predominantly thromboembolic complications. We have analysed clinical and laboratory data at the time of diagnosis in 328 patients with CBS deficiency from the E-HOD (European network and registry for Homocystinurias and methylation Defects) registry. We developed comprehensive criteria to classify patients into four groups of pyridoxine responsivity: non-responders (NR), partial, full and extreme responders (PR, FR and ER, respectively). All groups showed overlapping concentrations of plasma total homocysteine while pyridoxine responsiveness inversely correlated with plasma/serum methionine concentrations. The FR and ER groups had a later age of onset and diagnosis and a longer diagnostic delay than NR and PR patients. Lens dislocation was common in all groups except ER but the age of dislocation increased with increasing responsiveness. Developmental delay was commonest in the NR group while no ER patient had cognitive impairment. Thromboembolism was the commonest presenting feature in ER patients, whereas it was least likely at presentation in the NR group. This probably is due to the differences in ages at presentation: all groups had a similar number of thromboembolic events per 1000 patient-years. Clinical severity of CBS deficiency depends on the degree of pyridoxine responsiveness. Therefore, a standardised pyridoxine-responsiveness test in newly diagnosed patients and a critical review of previous assessments is indispensable to ensure adequate therapy and to prevent or reduce long-term complications.

Practical applicability of the STAMCO and ChOLE classification in cholesteatoma care.

BACKGROUND: To compare cholesteatoma care internationally and to evaluate outcomes, ear surgeons must use the same terminology. However, a clear universal definition on how to describe the extension, destruction and accompanying morbidity caused by the cholesteatoma is lacking. The practical applicability by means of interrater agreement is assessed for the STAMCO and the ChOLE classification. METHODS: A total of 134 adult patients derived from the nationwide multicentre study in the Netherlands, entitled Dutch Cholesteatoma Data (DCD) were included. Retrospective analysis of 134 surgical reports according to the STAMCO and ChOLE classification for localisation/extension of the cholesteatoma, complication status and ossicular chain status. Both the percentage agreement and the interrater agreement were determined for each item of the classifications and interrater agreement was compared between the classifications as a whole. RESULTS: Differences in interrater agreement were found for both the localisation/extension of the cholesteatoma and ossicular chain status. STAMCO classification derived from the surgical report scored better on the localisation/extension of the cholesteatoma, whereas the ChOLE classification derived from the surgical report scored better on the status of the ossicular chain. In both classifications, complication status had a low agreement level but was also poorly registered in the surgical reports. CONCLUSION: Both STAMCO and ChOLE will be beneficial in uniform registration of cholesteatoma pathology in practice. Modifications proposed for both classifications may make them even more practical applicable in the future. A common denominator obtained from these two classifications may be incorporated in a standardised surgical report to facilitate evaluation which make outcomes transferable towards both classifications.

No evidence for an association of plasma homocysteine levels and refractive error - Results from the population-based Gutenberg Health Study (GHS).

PURPOSE: There is a strong association between severe hyperhomocysteinemia and myopia. Thus we studied the hypothesis that even moderately increased levels of homocysteine (Hcy) might be a potentially treatable risk factor for myopia. METHODS: The Gutenberg Health Study (GHS) is a population-based, prospective, observational cohort study in Germany, including 15,010 participants aged between 35 and 74 at recruitment. The baseline examination was conducted from 2007-2012. Refraction was measured using autorefraction (HARK 599, Carl Zeiss AG, Jena, Germany). Hcy was measured by an immunoassay. We included only phakic participants without a history of corneal surgery or corneal laser treatment. We used linear regression models to evaluate the potential association between Hcy and refraction at baseline, and between Hcy and change in refraction between baseline and 5-year-follow-up examination. We used generalized estimating equation models to account for the correlation between fellow eyes. RESULTS: We included 13,749 participants, categorized as having no myopia (spherical equivalent > -0.75 D, 65.2%), low myopia (-0.75 D--2.75 D, 21.5%), moderate myopia (-3.00 D- 5.75 D, 9.8%) and high myopia (≤ -6 D, 3.5%). Median Hcy levels were similar in all groups (µmol/l). We observed no association of Hcy with refraction or 5-year change in refraction in the models adjusted for age, sex and socioeconomic status. CONCLUSION: We found no evidence for an association of Hcy levels and refractive error.

Classical homocystinuria: A common inborn error of metabolism? An epidemiological study based on genetic databases.

BACKGROUND: Biallelic pathogenic variants in CBS gene cause the most common form of homocystinuria, the classical homocystinuria (HCU). The worldwide prevalence of HCU is estimated to be 0.82:100,000 [95% CI, 0.39-1.73:100,000] according to clinical records and 1.09:100,000 [95% CI, 0.34-3.55:100,000] by neonatal screening. In this study, we aimed to estimate the minimal worldwide incidence of HCU. METHODS: The 25 most common pathogenic alleles of HCU were identified through a literature review. The incidence of HCU was estimated based on the frequency of these common pathogenic alleles in a large genomic database (gnomAD). RESULTS: The minimum worldwide incidence of HCU was estimated to be ~0.38:100,000, and the incidence was higher in Europeans non-Finnish (~0.72:100,000) and Latin Americans (~0.45:100,000) and lower in Africans (~0.20:100,000) and Asians (~0.02:100,000). CONCLUSION: Our data are in accordance with the only published metanalysis on this topic. To our surprise, the observed incidence of HCU in Europeans was much lower than those described in articles exploring small populations from northern Europe but was similar to the incidence described on the basis of neonatal screening programs. In our opinion, this large dataset analyzed and its population coverage gave us greater precision in the estimation of incidence.

Cystathionine beta synthase deficiency and brain edema associated with methionine excess under betaine supplementation: Four new cases and a review of the evidence.

CBS deficient individuals undergoing betaine supplementation without sufficient dietary methionine restriction can develop severe hypermethioninemia and brain edema. Brain edema has also been observed in individuals with severe hypermethioninemia without concomitant betaine supplementation. We systematically evaluated reports from 11 published and 4 unpublished patients with CBS deficiency and from additional four cases of encephalopathy in association with elevated methionine. We conclude that, while betaine supplementation does greatly exacerbate methionine accumulation, the primary agent causing brain edema is methionine rather than betaine. Clinical signs of increased intracranial pressure have not been seen in patients with plasma methionine levels below 559 µmol/L but occurred in one patient whose levels did not knowingly exceed 972 µmol/L at the time of manifestation. While levels below 500 µmol/L can be deemed safe it appears that brain edema can develop with plasma methionine levels close to 1000 µmol/L. Patients with CBS deficiency on betaine supplementation need to be regularly monitored for concordance with their dietary plan and for plasma methionine concentrations. Recurrent methionine levels above 500 µmol/L should alert clinicians to check for clinical signs and symptoms of brain edema and review dietary methionine intake. Levels approaching 1000 µmol/L do increase the risk of complications and levels exceeding 1000 µmol/L, despite best dietetic efforts, should be acutely addressed by reducing the prescribed betaine dose.

CO2-Lasertonsillotomy Under Local Anesthesia in Adults.

Tonsil-related complaints are very common among the adult population. Tonsillectomy under general anesthesia is currently the most performed surgical treatment in adults for such complaints. Unfortunately, tonsillectomy is an invasive treatment associated with a high complication rate and a long recovery time. Complications and a long recovery time are mostly related to removing the vascular and densely innervated capsule of the tonsils. Recently, CO2-lasertonsillotomy under local anesthesia has been demonstrated to be a viable alternative treatment for tonsil-related disease with a significantly shorter and less painful recovery period. The milder side-effect profile of CO2-lasertonsillotomy is likely related to leaving the tonsil capsule intact. The aim of the current report is to present a concise protocol detailing the execution of CO2-lasertonsillotomy under local anesthesia. This intervention has been performed successfully in our hospital in more than 1,000 patients and has been found to be safe and to be associated with a steep learning curve.

Analysis of the Qatari R336C cystathionine ß-synthase protein in mice.

Classical homocystinuria is a recessive inborn error of metabolism caused by mutations in the cystathionine beta-synthase (CBS) gene. The highest incidence of CBS deficiency in the world is found in the country of Qatar due to the combination of high rates of consanguinity and the presence of a founder mutation, c.1006C>T (p.R336C). This mutation does not respond to pyridoxine and is considered severe. Here we describe the creation of a mouse that is null for the mouse Cbs gene and expresses human p.R336C CBS from a zinc-inducible transgene (Tg-R336C Cbs -/- ). Zinc-treated Tg-R336C Cbs -/- mice have extreme elevation in both serum total homocysteine (tHcy) and liver tHcy compared with control transgenic mice. Both the steady-state protein levels and CBS enzyme activity levels in liver lysates from Tg-R336C Cbs -/- mice are significantly reduced compared to that found in Tg-hCBS Cbs -/- mice expressing wild-type human CBS. Treatment of Tg-R336C Cbs -/- mice with the proteasome inhibitor bortezomib results in stabilization of liver CBS protein and an increase in activity to levels found in corresponding Tg-hCBS Cbs -/- wild type mice. Surprisingly, serum tHcy did not fully correct even though liver enzyme activity was as high as control animals. This discrepancy is explained by in vitro enzymatic studies of mouse liver extracts showing that p.R336C causes reduced binding affinity for the substrate serine by almost 7-fold and significantly increased dependence on pyridoxal phosphate in the reaction buffer. These studies demonstrate that the p.R336C alteration effects both protein stability and substrate/cofactor binding.

Natural history, with clinical, biochemical, and molecular characterization of classical homocystinuria in the Qatari population.

Classical homocystinuria (HCU) is the most common inborn error of metabolism in Qatar, with an incidence of 1:1800, and is caused by the Qatari founder p.R336C mutation in the CBS gene. This study describes the natural history and clinical manifestations of HCU in the Qatari population. A single center study was performed between 2016 and 2017 in 126 Qatari patients, from 82 families. Detailed clinical and biochemical data were collected, and Stanford-Binet intelligence, quality of life and adherence to treatment assessments were conducted prospectively. Patients were assigned to one of three groups, according to the mode of diagnosis: (a) late diagnosis group (LDG), (b) family screening group (FSG), and (c) newborn screening group (NSG). Of the 126 patients, 69 (55%) were in the LDG, 44 (35%) in the NSG, and 13 (10%) in the FSG. The leading factors for diagnosis in the LDG were ocular manifestations (49%), neurological manifestations (45%), thromboembolic events (4%), and hyperactivity and behavioral changes (1%). Both FSG and NSG groups were asymptomatic at time of diagnosis. NSG had significantly higher intelligence quotient, quality of life, and adherence values compared with the LDG. The LDG and FSG had significantly higher methionine levels than the NSG. The LDG also had significantly higher total homocysteine levels than the NSG and FSG. Regression analysis confirmed these results even when adjusting for age at diagnosis, current age, or adherence. These findings increase the understanding of the natural history of HCU and highlight the importance of early diagnosis and treatment. SYNOPSIS: A study in 126 Qatari patients with HCU, including biochemical, clinical, and other key assessments, reveals that patients with a late clinical diagnosis have a poorer outcome, hereby highlighting the importance of early diagnosis and treatment.

Newborn screening for homocystinurias: Recent recommendations versus current practice.

PURPOSE: To assess how the current practice of newborn screening (NBS) for homocystinurias compares with published recommendations. METHODS: Twenty-two of 32 NBS programmes from 18 countries screened for at least one form of homocystinuria. Centres provided pseudonymised NBS data from patients with cystathionine beta-synthase deficiency (CBSD, n = 19), methionine adenosyltransferase I/III deficiency (MATI/IIID, n = 28), combined remethylation disorder (cRMD, n = 56) and isolated remethylation disorder (iRMD), including methylenetetrahydrofolate reductase deficiency (MTHFRD) (n = 8). Markers and decision limits were converted to multiples of the median (MoM) to allow comparison between centres. RESULTS: NBS programmes, algorithms and decision limits varied considerably. Only nine centres used the recommended second-tier marker total homocysteine (tHcy). The median decision limits of all centres were ≥ 2.35 for high and ≤ 0.44 MoM for low methionine, ≥ 1.95 for high and ≤ 0.47 MoM for low methionine/phenylalanine, ≥ 2.54 for high propionylcarnitine and ≥ 2.78 MoM for propionylcarnitine/acetylcarnitine. These decision limits alone had a 100%, 100%, 86% and 84% sensitivity for the detection of CBSD, MATI/IIID, iRMD and cRMD, respectively, but failed to detect six individuals with cRMD. To enhance sensitivity and decrease second-tier testing costs, we further adapted these decision limits using the data of 15 000 healthy newborns. CONCLUSIONS: Due to the favorable outcome of early treated patients, NBS for homocystinurias is recommended. To improve NBS, decision limits should be revised considering the population median. Relevant markers should be combined; use of the postanalytical tools offered by the CLIR project (Collaborative Laboratory Integrated Reports, which considers, for example, birth weight and gestational age) is recommended. tHcy and methylmalonic acid should be implemented as second-tier markers.

Phenotype, treatment practice and outcome in the cobalamin-dependent remethylation disorders and MTHFR deficiency: Data from the E-HOD registry.

AIM: To explore the clinical presentation, course, treatment and impact of early treatment in patients with remethylation disorders from the European Network and Registry for Homocystinurias and Methylation Defects (E-HOD) international web-based registry. RESULTS: This review comprises 238 patients (cobalamin C defect n = 161; methylenetetrahydrofolate reductase deficiency n = 50; cobalamin G defect n = 11; cobalamin E defect n = 10; cobalamin D defect n = 5; and cobalamin J defect n = 1) from 47 centres for whom the E-HOD registry includes, as a minimum, data on medical history and enrolment visit. The duration of observation was 127 patient years. In 181 clinically diagnosed patients, the median age at presentation was 30 days (range 1 day to 42 years) and the median age at diagnosis was 3.7 months (range 3 days to 56 years). Seventy-five percent of pre-clinically diagnosed patients with cobalamin C disease became symptomatic within the first 15 days of life. Total homocysteine (tHcy), amino acids and urinary methylmalonic acid (MMA) were the most frequently assessed disease markers; confirmatory diagnostics were mainly molecular genetic studies. Remethylation disorders are multisystem diseases dominated by neurological and eye disease and failure to thrive. In this cohort, mortality, thromboembolic, psychiatric and renal disease were rarer than reported elsewhere. Early treatment correlates with lower overall morbidity but is less effective in preventing eye disease and cognitive impairment. The wide variation in treatment hampers the evaluation of particular therapeutic modalities. CONCLUSION: Treatment improves the clinical course of remethylation disorders and reduces morbidity, especially if started early, but neurocognitive and eye symptoms are less responsive. Current treatment is highly variable. This study has the inevitable limitations of a retrospective, registry-based design.

In silico and in vivo models for Qatari-specific classical homocystinuria as basis for development of novel therapies.

Homocystinuria is a rare inborn error of methionine metabolism caused by cystathionine ß-synthase (CBS) deficiency. The prevalence of homocystinuria in Qatar is 1:1,800 births, mainly due to a founder Qatari missense mutation, c.1006C>T; p.R336C (p.Arg336Cys). We characterized the structure-function relationship of the p.R336C-mutant protein and investigated the effect of different chemical chaperones to restore p.R336C-CBS activity using three models: in silico, ΔCBS yeast, and CRISPR/Cas9 p.R336C knock-in HEK293T and HepG2 cell lines. Protein modeling suggested that the p.R336C induces severe conformational and structural changes, perhaps influencing CBS activity. Wild-type CBS, but not the p.R336C mutant, was able to restore the yeast growth in ΔCBS-deficient yeast in a complementation assay. The p.R336C knock-in HEK293T and HepG2 cells decreased the level of CBS expression and reduced its structural stability; however, treatment of the p.R336C knock-in HEK293T cells with betaine, a chemical chaperone, restored the stability and tetrameric conformation of CBS, but not its activity. Collectively, these results indicate that the p.R336C mutation has a deleterious effect on CBS structure, stability, and activity, and using the chemical chaperones approach for treatment could be ineffective in restoring p.R336C CBS activity.

Adenosine Kinase Deficiency: Report and Review.

Adenosine kinase (ADK) deficiency (OMIM [online mendelian inheritance in man]: 614300) is an autosomal recessive disorder of adenosine and methionine metabolism, with a unique clinical phenotype, mainly involving the central nervous system and dysmorphic features. Patients usually present early in life with sepsis-like symptoms, respiratory difficulties, and neonatal jaundice. Subsequently, patients demonstrate hypotonia and global developmental delay. Biochemically, methionine is elevated with normal homocysteine levels and the diagnosis is confirmed through molecular analysis of the ADK gene. There is no curative treatment; however, a methionine-restricted diet has been tried with variable outcomes. Herein, we report a 4-year-old Saudi female with global developmental delay, hypotonia, and dysmorphic features. Interestingly, she has a tall stature, developmental dysplasia of the hip, optic nerve gliosis, and tigroid fundus. We found a mutation not reported previously and we compared the current case with previously reported cases. We alert clinicians to consider ADK deficiency in any neonate presenting with global developmental delay, hypotonia, dysmorphic features, and high methionine levels.

Three Main Causes of Homocystinuria: CBS, cblC and MTHFR Deficiency. What do they Have in Common?

Abstract Genetic homocystinurias are a group of inborn errors of metabolism that result in the massive excretion of homocysteine (Hcy) in the urine due to Hcy accumulation in the body, usually causing neurological and cardiovascular complications. The three most frequent causes are classical homocystinuria [deficiency of cystathionine beta-synthase (CBS)], methylmalonic aciduria with homocystinuria, cblC type (cblC deficiency) and severe methylenetetrahydrofolate reductase (MTHFR) deficiency. In this review, we highlight the similarities and differences among these disorders. Briefly, their joint manifestation is the accumulation of tHcy, however, the other sulfur amino acids show various and even invers profiles. Vascular disease, developmental delay and seizures are found in all homocystinurias, nevertheless, the complications of CNS differ in a wide variety of presentations and severities and are apparently less pronounced in CBS deficiency. Moreover, patients with remethylation defects typically do not present ectopia lentis and bone disturbances, tall stature and osteoporosis. Whereas hematological alterations, such as megaloblastic anemia, thrombocytopenia neutropenia and life-threatening microangiopathy, are specific findings of cblC deficiency.

Folinic Acid Increases Protein Arginine Methylation in Human Endothelial Cells.

Elevated plasma total homocysteine (tHcy) is associated with increased risk of cardiovascular disease, but the mechanisms underlying this association are not completely understood. Cellular hypomethylation has been suggested to be a key pathophysiologic mechanism, since S-adenosylhomocysteine (AdoHcy), the Hcy metabolic precursor and a potent inhibitor of methyltransferase activity, accumulates in the setting of hyperhomocysteinemia. In this study, the impact of folate and methionine on intracellular AdoHcy levels and protein arginine methylation status was studied. Human endothelial cells were incubated with increasing concentrations of folinic acid (FnA), a stable precursor of folate, with or without methionine restriction. The levels of intracellular AdoHcy and AdoMet, tHcy in the cell culture medium, and protein-incorporated methylarginines were evaluated by suitable liquid chromatography techniques. FnA supplementation, with or without methionine restriction, reduced the level of tHcy and did not affect intracellular AdoMet levels. Interestingly, FnA supplementation reduced intracellular AdoHcy levels only in cells grown under methionine restriction. Furthermore, these cells also displayed increased protein arginine methylation status. These observations suggest that folic acid supplementation may enhance cellular methylation capacity under a low methionine status. Our results lead us to hypothesize that the putative benefits of folic acid supplementation in restoring endothelial homeostasis, thus preventing atherothrombotic events, should be reevaluated in subjects under a methionine restriction diet.