Risk stratification and subclinical phenotyping of dilated and/or arrhythmogenic cardiomyopathy mutation-positive relatives: CVON eDETECT consortium.

In relatives of index patients with dilated cardiomyopathy and arrhythmogenic cardiomyopathy, early detection of disease onset is essential to prevent sudden cardiac death and facilitate early treatment of heart failure. However, the optimal screening interval and combination of diagnostic techniques are unknown. The clinical course of disease in index patients and their relatives is variable due to incomplete and age-dependent penetrance. Several biomarkers, electrocardiographic and imaging (echocardiographic deformation imaging and cardiac magnetic resonance imaging) techniques are promising non-invasive methods for detection of subclinical cardiomyopathy. However, these techniques need optimisation and integration into clinical practice. Furthermore, determining the optimal interval and intensity of cascade screening may require a personalised approach. To address this, the CVON-eDETECT (early detection of disease in cardiomyopathy mutation carriers) consortium aims to integrate electronic health record data from long-term follow-up, diagnostic data sets, tissue and plasma samples in a multidisciplinary biobank environment to provide personalised risk stratification for heart failure and sudden cardiac death. Adequate risk stratification may lead to personalised screening, treatment and optimal timing of implantable cardioverter defibrillator implantation. In this article, we describe non-invasive diagnostic techniques used for detection of subclinical disease in relatives of index patients with dilated cardiomyopathy and arrhythmogenic cardiomyopathy.

How to inform relatives at risk of hereditary diseases? A mixed-methods systematic review on patient attitudes.

When a genetic disease-causing variant causing autosomal dominant diseases is identified, predictive DNA testing is possible for at-risk relatives to investigate whether they are carrying the familial variant. In current practice, the proband is asked to inform at-risk relatives, often supported by a family letter. This review summarizes the literature on preferences of probands and relatives regarding how and by whom at-risk relatives should be informed. A search involving digital databases (Pubmed, Medline, and PsycInfo) focusing on patient attitudes toward informing relatives at risk of autosomal dominant onco-, cardio-, or neurogenetic disease, resulted in 1,431 screened records, of which 117 full-text papers were assessed. Eventually, 32 studies were selected. This review shows that a majority of participants was in favor of someone in the family to inform their at-risk relatives, with participants generally feeling responsible for informing relatives at risk themselves. However, variation in patient preferences regarding who should inform was observed. Face-to-face disclosure by the proband with additional information material for relatives provided by HCPs was most appreciated. Actively offered support of healthcare professionals was desired. In conclusion, although the family-mediated approach was appreciated by a majority of participants, support by healthcare professionals was desired. By taking patient attitudes into account, the approach used to inform at-risk relatives could be improved. Subsequently, more relatives will be informed and enabled to attend genetic counseling and make an informed decision regarding predictive DNA testing. Further research on patient attitudes, specifying for disease type and cultural background, is needed.

Genotype-phenotype correlations of low-frequency variants in the complement system in renal disease and age-related macular degeneration.

Genetic alterations in the complement system have been linked to a variety of diseases, including atypical hemolytic uremic syndrome (aHUS), C3 glomerulopathy (C3G), and age-related macular degeneration (AMD). We performed sequence analysis of the complement genes complement factor H (CFH), complement factor I (CFI), and complement C3 (C3) in 866 aHUS/C3G and 697 AMD patients. In total, we identified 505 low-frequency alleles, representing 121 unique variants, of which 51 are novel. CFH contained the largest number of unique low-frequency variants (n = 64; 53%), followed by C3 (n = 32; 26%) and CFI (n = 25; 21%). A substantial number of variants were found in both patients groups (n = 48; 40%), while 41 (34%) variants were found only in aHUS/C3G and 32 (26%) variants were AMD specific. Genotype-phenotype correlations between the disease groups identified a higher frequency of protein altering alleles in short consensus repeat 20 (SCR20) of factor H (FH), and in the serine protease domain of factor I (FI) in aHUS/C3G patients. In AMD, a higher frequency of protein-altering alleles was observed in SCR3, SCR5, and SCR7 of FH, the SRCR domain of FI, and in the MG3 domain of C3. In conclusion, we observed a substantial overlap of variants between aHUS/C3G and AMD; however, there is a distinct clustering of variants within specific domains.

Complement activation patterns in atypical haemolytic uraemic syndrome during acute phase and in remission.

Atypical haemolytic uraemic syndrome (aHUS) is associated with (genetic) alterations in alternative complement pathway. Nevertheless, comprehensive evidence that the complement system in aHUS patients is more prone to activation is still lacking. Therefore, we performed a thorough analysis of complement activation in acute phase and in remission of this disease. Complement activation patterns of the aHUS patients in acute phase and in remission were compared to those of healthy controls. Background levels of complement activation products C3b/c, C3bBbP and terminal complement complex (TCC) were measured using enzyme-linked immunosorbent assay (ELISA) in ethylenediamine tetraacetic acid (EDTA) plasma. In vitro-triggered complement activation in serum samples was studied using zymosan-coating and pathway-specific assay. Furthermore, efficiencies of the C3b/c, C3bBbP and TCC generation in fluid phase during spontaneous activation were analysed. Patients with acute aHUS showed elevated levels of C3b/c (P < 0·01), C3bBbP (P < 0·0001) and TCC (P < 0·0001) in EDTA plasma, while values of patients in remission were normal, compared to those of healthy controls. Using data from a single aHUS patient with complement factor B mutation we illustrated normalization of complement activation during aHUS recovery. Serum samples from patients in remission showed normal in vitro patterns of complement activation and demonstrated normal kinetics of complement activation in the fluid phase. Our data indicate that while aHUS patients have clearly activated complement in acute phase of the disease, this is not the case in remission of aHUS. This knowledge provides important insight into complement regulation in aHUS and may have an impact on monitoring of these patients, particularly when using complement inhibition therapy.

A morphological and functional comparison of proximal tubule cell lines established from human urine and kidney tissue.

Promising renal replacement therapies include the development of a bioartificial kidney using functional human kidney cell models. In this study, human conditionally immortalized proximal tubular epithelial cell (ciPTEC) lines originating from kidney tissue (ciPTEC-T1 and ciPTEC-T2) were compared to ciPTEC previously isolated from urine (ciPTEC-U). Subclones of all ciPTEC isolates formed tight cell layers on Transwell inserts as determined by transepithelial resistance, inulin diffusion, E-cadherin expression and immunocytochemisty. Extracellular matrix genes collagen I and -IV α1 were highly present in both kidney tissue derived matured cell lines (p<0.001) compared to matured ciPTEC-U, whereas matured ciPTEC-U showed a more pronounced fibronectin I and laminin 5 gene expression (p<0.01 and p<0.05, respectively). Expression of the influx carrier Organic Cation Transporter 2 (OCT-2), and the efflux pumps P-glycoprotein (P-gp), Multidrug Resistance Protein 4 (MRP4) and Breast Cancer Resistance Protein (BCRP) were confirmed in the three cell lines using real-time PCR and Western blotting. The activities of OCT-2 and P-gp were sensitive to specific inhibition in all models (p<0.001). The highest activity of MRP4 and BCRP was demonstrated in ciPTEC-U (p<0.05). Finally, active albumin reabsorption was highest in ciPTEC-T2 (p<0.001), while Na(+)-dependent phosphate reabsorption was most abundant in ciPTEC-U (p<0.01). In conclusion, ciPTEC established from human urine or kidney tissue display comparable functional PTEC specific transporters and physiological characteristics, providing ideal human tools for bioartificial kidney development.

Uremic toxins inhibit renal metabolic capacity through interference with glucuronidation and mitochondrial respiration.

During chronic kidney disease (CKD), drug metabolism is affected leading to changes in drug disposition. Furthermore, there is a progressive accumulation of uremic retention solutes due to impaired renal clearance. Here, we investigated whether uremic toxins can influence the metabolic functionality of human conditionally immortalized renal proximal tubule epithelial cells (ciPTEC) with the focus on UDP-glucuronosyltransferases (UGTs) and mitochondrial activity. Our results showed that ciPTEC express a wide variety of metabolic enzymes, including UGTs. These enzymes were functionally active as demonstrated by the glucuronidation of 7-hydroxycoumarin (7-OHC; K(m) of 12±2µM and a V(max) of 76±3pmol/min/mg) and p-cresol (K(m) of 33±13µM and a V(max) of 266±25pmol/min/mg). Furthermore, a wide variety of uremic toxins, including indole-3-acetic acid, indoxyl sulfate, phenylacetic acid and kynurenic acid, reduced 7-OHC glucuronidation with more than 30% as compared with controls (p<0.05), whereas UGT1A and UGT2B protein expressions remained unaltered. In addition, our results showed that several uremic toxins inhibited mitochondrial succinate dehydrogenase (i.e. complex II) activity with more than 20% as compared with controls (p<0.05). Moreover, indole-3-acetic acid decreased the reserve capacity of the electron transport system with 18% (p<0.03). In conclusion, this study shows that multiple uremic toxins inhibit UGT activity and mitochondrial activity in ciPTEC, thereby affecting the metabolic capacity of the kidney during CKD. This may have a significant impact on drug and uremic retention solute disposition in CKD patients.

A novel method for direct measurement of complement convertases activity in human serum.

Complement convertases are enzymatic complexes that play a central role in sustaining and amplification of the complement cascade. Impairment of complement function leads directly or indirectly to pathological conditions, including higher infection rate, kidney diseases, autoimmune- or neurodegenerative diseases and ischaemia-reperfusion injury. An assay for direct measurement of activity of the convertases in patient sera is not available. Existing assays testing convertase function are based on purified complement components and, thus, convertase formation occurs under non-physiological conditions. We designed a new assay, in which C5 blocking compounds enabled separation of the complement cascade into two phases: the first ending at the stage of C5 convertases and the second ending with membrane attack complex formation. The use of rabbit erythrocytes or antibody-sensitized sheep erythrocytes as the platforms for convertase formation enabled easy readout based on measurement of haemolysis. Thus, properties of patient sera could be studied directly regarding convertase activity and membrane attack complex formation. Another advantage of this assay was the possibility to screen for host factors such as C3 nephritic factor and other anti-complement autoantibodies, or gain-of-function mutations, which prolong the half-life of complement convertases. Herein, we present proof of concept, detailed description and validation of this novel assay.

Posttraumatic stress disorder is characterized by functional dysregulation of dermal fibroblasts.

Incidence of mental health disorders are rising in modernity, with psychological stress linked to a propensity for developing various chronic diseases due to a relative inability of the body to counter the allostatic load on cellular level. Despite these high rates of comorbidities associated with posttraumatic stress disorder (PTSD), there is still a lack of understanding in terms of the peripheral effects of PTSD on tissue level. Therefore, the purpose of this study was to profile basal dermal fibroblast functional status in PTSD using a wide range of markers involved in the cell-to-cell communication facilitated by fibroblasts. Primary dermal fibroblasts derived from patients diagnosed with PTSD (n = 11) and matched trauma exposed controls (i.e. who did not develop PTSD, n = 10) were cultured using standard techniques. The patients and controls were matched based on age, sex, body-mass index (BMI) and lifestyle. The growth rate, population doubling time, cell surface marker expression (CD31, FNDC5) (flow cytometry), secretome (TIMP-2, MMP-9) (ELISAs), intracellular signalling capacity (Fluo-4 Ca2+ flux) and gene expression (IL-6, IL-10, PTX-3, iNOS, Arg1) were compared between groups. The data illustrated significant PTSD-associated fibroblast conditioning resulting in a blunted signalling capacity. This observation highlights the importance of including tissue-specific investigations in future studies focused on elucidating the association between PTSD and subsequent risk for somatic disease.

Increased human dermal microvascular endothelial cell survival induced by cysteamine.

BACKGROUND: Cystinosis is an autosomal recessive disease caused by intralysosomal cystine accumulation, treated with cysteamine. Recently, new adverse effects of cysteamine were reported. Skin biopsies showed microvascular proliferation (angioendotheliomatosis). To examine the mechanism of angioendotheliomatosis associated with cysteamine toxicity, we examined the effect of cysteamine on human dermal microvascular endothelial cells (HDMVEC). METHODS: After cysteamine exposure (range 0-3.0 mM) during 24 h, cell viability was measured using water soluble tetrazolium salt-1 (WST-1) in both control HDMVEC and fibroblasts. Cell proliferation and apoptosis rate were measured in HDMVEC by bromodeoxyuridine (BrdU) incorporation and caspase 3 and caspase 7 activity, respectively. Intracellular glutathione (GSH) was measured in HDMVEC after cysteamine exposure of 0, 0.1 or 1.0 mM. Medium and cysteamine were refreshed every 6 h to mimic the in vivo situation. Next, cell viability in HDMVEC was measured after 24 h of GSH exposure (range 0-10.0 mM). RESULTS: HDMVEC viability and proliferation increased after cysteamine exposure 0.03-3.0 mM (p < 0.01) and 0.03-1.0 mM (p = 0.01) respectively; cell viability in fibroblasts was not affected by incubation with cysteamine. Apoptosis remained unaffected by incubation with 0-1.0 mM cysteamine, 3.0 mM caused increased apoptosis. Intracellular GSH was significantly increased after incubation with cysteamine 0.1 mM (p = 0.02) and 1.0 mM (p < 0.01). HDMVEC viability increased after exposure to GSH 1.0-5.0 mM (p < 0.01). CONCLUSION: Cysteamine concentrations, similar to those described in plasma of cystinosis patients, stimulate HDMVEC viability and proliferation and increase intracellular GSH content. We postulate that this mechanism might underlie angioendotheliomatosis induced by cysteamine.

A candidate genetic risk factor for vascular disease: a common mutation in methylenetetrahydrofolate reductase.

Hyperhomocysteinaemia has been identified as a risk factor for cerebrovascular, peripheral vascular and coronary heart disease. Elevated levels of plasma homocysteine can result from genetic or nutrient-related disturbances in the trans-sulphuration or re-methylation pathways for homocysteine metabolism. 5, 10-Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5, 10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, the predominant circulatory form of folate and carbon donor for the re-methylation of homocysteine to methionine. Reduced MTHFR activity with a thermolabile enzyme has been reported in patients with coronary and peripheral artery disease. We have identified a common mutation in MTHFR which alters a highly-conserved amino acid; the substitution occurs at a frequency of approximately 38% of unselected chromosomes. The mutation in the heterozygous or homozygous state correlates with reduced enzyme activity and increased thermolability in lymphocyte extracts; in vitro expression of a mutagenized cDNA containing the mutation confirms its effect on thermolability of MTHFR. Finally, individuals homozygous for the mutation have significantly elevated plasma homocysteine levels. This mutation in MTHFR may represent an important genetic risk factor in vascular disease.

Dominant isolated renal magnesium loss is caused by misrouting of the Na(+),K(+)-ATPase gamma-subunit.

Primary hypomagnesaemia is composed of a heterogeneous group of disorders characterized by renal or intestinal Mg(2+) wasting, often associated with disturbances in Ca(2+) excretion. We identified a putative dominant-negative mutation in the gene encoding the Na(+), K(+)-ATPase gamma-subunit (FXYD2), leading to defective routing of the protein in a family with dominant renal hypomagnesaemia.

Methodology for risk-based monitoring of contaminants in food - A case study in cereals and fish.

In this study, a methodology was developed that can be used as input for risk-based monitoring plans for chemical contaminants in food products. The novel methodology was applied to a case study in which cereals and fish were evaluated simultaneously for the possible presence of mycotoxins and heavy metals. The methodology was based on hazard quotients that were estimated by dividing the daily intake - using concentrations of the contaminants in the different food products and consumption of the respective products combined per product group - by the health based guidance value (HBGV) or reference points used for assessing potential health concerns (RPHC). The most relevant hazard-product combinations were further ranked based on the volume of import of the ingredients, per import country and a defined contaminant prevalence level per country. For fish, the hazard quotients were around ten times lower compared to the highest hazard quotients in cereals. Consumption of molluscs, mackerel-type fish and herring-type fish contaminated with mercury contributed most to the HBGV or RPHC. The top 25 hazard-product combinations for various age groups included: aflatoxin B1 in combination with wheat, rice (products), maize (products), and pasta, zearalenone in combination with wheat (products), T2/HT2-toxin in combination with rice (products), and DON in combination with wheat (products). The methodology presented showed to be useful in identifying the most relevant hazard-food-age group combinations and the most relevant import countries linked to these that should be included in the monitoring. As such, the method can help risk managers in establishing risk-based monitoring programs.

Eculizumab Rescue Therapy in Patients With Recurrent Atypical Hemolytic Uremic Syndrome After Kidney Transplantation.

Introduction: Since 2016, kidney transplantation in patients with atypical hemolytic uremic syndrome (aHUS) in the Netherlands is performed without eculizumab prophylaxis. Eculizumab is given in case of posttransplant aHUS recurrence. Eculizumab therapy is monitored in the CUREiHUS study. Methods: All participating kidney transplant patients who received eculizumab therapy for a suspected posttransplant aHUS recurrence were evaluated. Overall recurrence rate was monitored prospectively at Radboud University Medical Center. Results: In the period from January 2016 until October 2020, we included 15 (12 females, 3 males; median age 42 years, range 24-66 years) patients with suspected aHUS recurrence after kidney transplantation in this study. The time interval to recurrence showed a bimodal distribution. Seven patients presented early after transplantation (median 3 months, range 0.3-8.8 months), with typical aHUS features: rapid loss of estimated glomerular filtration rate (eGFR) and laboratory signs of thrombotic microangiopathy (TMA). Eight patients presented late (median 46 months, range 18-69 months) after transplantation. Of these, only 3 patients had systemic TMA, whereas 5 patients presented with slowly deteriorating eGFR without systemic TMA. Treatment with eculizumab resulted in improvement or stabilization of eGFR in 14 patients. Eculizumab discontinuation was tried in 7 patients; however, it was successful only in 3. At the end of the follow-up (median 29 months, range 3-54 months after start of eculizumab), 6 patients had eGFR <30 ml/min per 1.73 m2. Graft loss had occurred in 3 of them. Overall, aHUS recurrence rate without eculizumab prophylaxis was 23%. Conclusions: Rescue treatment of posttransplant aHUS recurrence is effective; however, some patients suffer from irreversible loss of kidney function, likely caused by delayed diagnosis and treatment and/or too aggressive discontinuation of eculizumab. Physicians should be aware that recurrence of aHUS can present without evidence of systemic TMA.

Natural disease course and genotype-phenotype correlations in Complex I deficiency caused by nuclear gene defects: what we learned from 130 cases.

Mitochondrial complex I is the largest multi-protein enzyme complex of the oxidative phosphorylation system. Seven subunits of this complex are encoded by the mitochondrial and the remainder by the nuclear genome. We review the natural disease course and signs and symptoms of 130 patients (four new cases and 126 from literature) with mutations in nuclear genes encoding structural complex I proteins or those involved in its assembly. Complex I deficiency caused by a nuclear gene defect is usually a non-dysmorphic syndrome, characterized by severe multi-system organ involvement and a poor prognosis. Age at presentation may vary, but is generally within the first year of life. The most prevalent symptoms include hypotonia, nystagmus, respiratory abnormalities, pyramidal signs, dystonia, psychomotor retardation or regression, failure to thrive, and feeding problems. Characteristic symptoms include brainstem involvement, optic atrophy and Leigh syndrome on MRI, either or not in combination with internal organ involvement and lactic acidemia. Virtually all children ultimately develop Leigh syndrome or leukoencephalopathy. Twenty-five percent of the patients died before the age of six months, more than half before the age of two and 75 % before the age of ten years. Some patients showed recovery of certain skills or are still alive in their thirties . No clinical, biochemical, or genetic parameters indicating longer survival were found. No clear genotype-phenotype correlations were observed, however defects in some genes seem to be associated with a better or poorer prognosis, cardiomyopathy, Leigh syndrome or brainstem lesions.

Associations between BMI and brain structures involved in food intake regulation in first-episode schizophrenia spectrum disorders and healthy controls.

Structural brain differences have been described in first-episode schizophrenia spectrum disorders (FES), and often overlap with those evident in the metabolic syndrome (MetS). We examined the associations between body mass index (BMI) and brain structures involved in food intake regulation in minimally treated FES patients (n = 117) compared to healthy controls (n = 117). The effects of FES diagnosis, BMI and their interactions on our selected prefrontal cortical thickness and subcortical gray matter volume regions of interest (ROIs) were investigated with hierarchical multivariate regressions, followed by post-hoc regressions for the individual ROIs. In a secondary analysis, we examined the relationships of other MetS risk factors and psychopathology with the brain ROIs. Both illness and BMI significantly predicted the grouped prefrontal cortical thickness ROIs, whereas only BMI predicted the grouped subcortical volume ROIs. For the individual ROIs, schizophrenia diagnosis predicted thinner left and right frontal pole and right lateral OFC thickness, and increased BMI predicted thinner left and right caudal ACC thickness. There were no significant main or interaction effects for diagnosis and BMI on any of the individual subcortical volume ROIs. Secondary analyses suggest associations between several brain ROIs and individual MetS risk factors, but not with psychopathology. Our findings indicate differential, independent effects for FES diagnosis and BMI on brain structures. Limited evidence suggests that the BMI effects are more prominent in FES. Exploratory analyses suggest associations between other MetS risk factors and some brain ROIs.

Hyperhomocysteinemia: a trigger for complement-mediated TMA?

A 34-year-old man of North African descent was referred to the emergency department because of malignant hypertension (220/113 mmHg), acute visual disturbances and acute kidney failure (serum creatinine 14.0 mg/dL). Blood analysis was compatible with thrombotic microangiopathy (TMA). Kidney biopsy confirmed this diagnosis with histological changes including intimal edema, arteriolar thrombi, and severe tubulointerstitial damage. Fundoscopy showed hypertensive retinopathy stage IV. Subsequent biochemical screening revealed normal complement testing and a marked elevation in homocysteine concentration (161 µmol/L; normal value 7-15 µmol/L). Other secondary causes of TMA were excluded. Further genetic testing for cobalamin C (cblC) deficiency showed no pathogenic mutations in the MMACHC gene. However, a homozygous c.665C>T polymorphism (NM_005957.4) in the methylenetetrahydrofolate reductase (MTHFR) gene was found explaining the severe hyperhomocysteinemia due to reduced activity of MTHFR. Additional genetic testing for alternative complement pathway proteins showed mutations in the genes encoding factor H and factor B, both categorized as possibly pathogenic using mutation prediction software. This is the first described case of TMA in a patient with severe hyperhomocysteinemia caused by a genetic defect other than cblC. We postulate that endothelial damage due to hyperhomocysteinemia and hypertension could have triggered the TMA episode in this patient with two possible predisposing pathogenic mutations in the alternative complement pathway. Furthermore, our case demonstrates the need for complete full diagnostic testing in patients with TMA.

The treatment gap for mental disorders in adults enrolled in HIV treatment programmes in South Africa: a cohort study using linked electronic health records.

AIMS: Mental disorders are common in people living with HIV (PLWH) but often remain untreated. This study aimed to explore the treatment gap for mental disorders in adults followed-up in antiretroviral therapy (ART) programmes in South Africa and disparities between ART programmes regarding the provision of mental health services. METHODS: We conducted a cohort study using ART programme data and linked pharmacy and hospitalisation data to examine the 12-month prevalence of treatment for mental disorders and factors associated with the rate of treatment for mental disorders among adults, aged 15-49 years, followed-up from 1 January 2012 to 31 December 2017 at one private care, one public tertiary care and two pubic primary care ART programmes in South Africa. We calculated the treatment gap for mental disorders as the discrepancy between the 12-month prevalence of mental disorders in PLWH (aged 15-49 years) in South Africa (estimated based on data from the Global Burden of Disease study) and the 12-month prevalence of treatment for mental disorders in ART programmes. We calculated adjusted rate ratios (aRRs) for factors associated with the treatment rate of mental disorders using Poisson regression. RESULTS: In total, 182 285 ART patients were followed-up over 405 153 person-years. In 2017, the estimated treatment gap for mental disorders was 40.5% (95% confidence interval [CI] 19.5-52.9) for patients followed-up in private care, 96.5% (95% CI 95.0-97.5) for patients followed-up in public primary care and 65.0% (95% CI 36.5-85.1) for patients followed-up in public tertiary care ART programmes. Rates of treatment with antidepressants, anxiolytics and antipsychotics were 17 (aRR 0.06, 95% CI 0.06-0.07), 50 (aRR 0.02, 95% CI 0.01-0.03) and 2.6 (aRR 0.39, 95% CI 0.35-0.43) times lower in public primary care programmes than in the private sector programmes. CONCLUSIONS: There is a large treatment gap for mental disorders in PLWH in South Africa and substantial disparities in access to mental health services between patients receiving ART in the public vs the private sector. In the public sector and especially in public primary care, PLWH with common mental disorders remain mostly untreated.

Sequence variants in four candidate genes (NIPSNAP1, GBAS, CHCHD1 and METT11D1) in patients with combined oxidative phosphorylation system deficiencies.

The oxidative phosphorylation (OXPHOS) system, comprising five enzyme complexes, is located in the inner membrane of mitochondria and is the final biochemical pathway in oxidative ATP production. Defects in this energy-generating system can cause a wide range of clinical symptoms; these diseases are often progressive and multisystemic. Numerous genes have been implicated in OXPHOS deficiencies and many mutations have been described. However, in a substantial number of patients with decreased enzyme activities of two or more OXPHOS complexes, no mutations in the mitochondrial DNA or in nuclear genes known to be involved in these disorders have been found. In this study, four nuclear candidate genes--NIPSNAP1, GBAS, CHCHD1 and METT11D1--were screened for mutations in 22 patients with a combined enzymatic deficiency of primarily the OXPHOS complexes I, III and IV to determine whether a mutation in one of these genes could explain the mitochondrial disorder. For each variant not yet reported as a polymorphism, 100 control samples were screened for the presence of the variant. This way we identified 14 new polymorphisms and 2 presumably non-pathogenic mutations. No mutations were found that could explain the mitochondrial disorder in the patients investigated in this study. Therefore, the genetic defect in these patients must be located in other nuclear genes involved in mtDNA maintenance, transcription or translation, in import, processing or degradation of nuclear encoded mitochondrial proteins, or in assembly of the OXPHOS system.