Triheptanoin for the treatment of long-chain fatty acid oxidation disorders: Final results of an open-label, long-term extension study.

Long-chain fatty acid oxidation disorders (LC-FAODs) result in life-threatening energy metabolism deficiencies/energy source depletion. Triheptanoin is an odd-carbon, medium chain triglyceride (that is an anaplerotic substrate of calories and fatty acids) for treating pediatric and adult patients with LC-FAODs. Study CL202 (NCT02214160), an open-label extension study of study CL201 (NCT01886378), evaluated the long-term safety/efficacy of triheptanoin in patients with LC-FAODs (N = 94), including cohorts who were triheptanoin naïve (n = 33) or had received triheptanoin in study CL201 (n = 24) or in investigator-sponsored trials/expanded access programs (IST/EAPs; n = 37). Primary endpoint was the annualized rate of LC-FAOD major clinical events (MCEs; rhabdomyolysis, hypoglycemia, cardiomyopathy). Mean ± standard deviation (SD) triheptanoin treatment durations were 27.4 ± 19.9, 46.9 ± 13.6, and 49.6 ± 21.4 months for the triheptanoin-naïve, CL201 rollover, and IST/EAP cohorts, respectively. In the triheptanoin-naïve cohort, median (interquartile range [IQR]) MCE rate significantly decreased from 2.00 (0.67-3.33) events/patient/year pre-triheptanoin to 0.28 (0.00-1.43) events/patient/year with triheptanoin (p = 0.0343), a reduction of 86%. In the CL201 rollover cohort, mean ± SD MCE rate significantly decreased from 1.76 ± 1.64 events/patient/year pre-triheptanoin to 1.00 ± 1.00 events/patient/year with triheptanoin (p = 0.0347), a reduction of 43%. In the IST/EAP cohort, mean ± SD MCE rate was 1.40 ± 2.37 (median [IQR] 0.57 [0.00-1.67]) events/patient/year with triheptanoin. Safety data were consistent with previous observations. Treatment-related treatment-emergent adverse events (TEAEs) occurred in 68.1% of patients and were mostly mild/moderate in severity. Five patients had seven serious treatment-related TEAEs; all resolved. Our results confirm the long-term efficacy of triheptanoin for patients with LC-FAOD.

Impact of the SARS-CoV-2 pandemic on the health of individuals with intoxication-type metabolic diseases-Data from the E-IMD consortium.

The SARS-CoV-2 pandemic challenges healthcare systems worldwide. Within inherited metabolic disorders (IMDs) the vulnerable subgroup of intoxication-type IMDs such as organic acidurias (OA) and urea cycle disorders (UCD) show risk for infection-induced morbidity and mortality. This study (observation period February 2020 to December 2021) evaluates impact on medical health care as well as disease course and outcome of SARS-CoV-2 infections in patients with intoxication-type IMDs managed by participants of the European Registry and Network for intoxication type metabolic diseases Consortium (E-IMD). Survey's respondents managing 792 patients (n = 479 pediatric; n = 313 adult) with intoxication-type IMDs (n = 454 OA; n = 338 UCD) in 14 countries reported on 59 (OA: n = 36; UCD: n = 23), SARS-CoV-2 infections (7.4%). Medical services were increasingly requested (95%), mostly alleviated by remote technologies (86%). Problems with medical supply were scarce (5%). Regular follow-up visits were reduced in 41% (range 10%-50%). Most infected individuals (49/59; 83%) showed mild clinical symptoms, while 10 patients (17%; n = 6 OA including four transplanted MMA patients; n = 4 UCD) were hospitalized (metabolic decompensation in 30%). ICU treatment was not reported. Hospitalization rate did not differ for diagnosis or age group (p = 0.778). Survival rate was 100%. Full recovery was reported for 100% in outpatient care and 90% of hospitalized individuals. SARS-CoV-2 impacts health care of individuals with intoxication-type IMDs worldwide. Most infected individuals, however, showed mild symptoms and did not require hospitalization. SARS-CoV-2-induced metabolic decompensations were usually mild without increased risk for ICU treatment. Overall prognosis of infected individuals is very promising and IMD-specific or COVID-19-related complications have not been observed.

Recommendations for diagnosing and managing individuals with glutaric aciduria type 1: Third revision.

Glutaric aciduria type 1 is a rare inherited neurometabolic disorder of lysine metabolism caused by pathogenic gene variations in GCDH (cytogenic location: 19p13.13), resulting in deficiency of mitochondrial glutaryl-CoA dehydrogenase (GCDH) and, consequently, accumulation of glutaric acid, 3-hydroxyglutaric acid, glutaconic acid and glutarylcarnitine detectable by gas chromatography/mass spectrometry (organic acids) and tandem mass spectrometry (acylcarnitines). Depending on residual GCDH activity, biochemical high and low excreting phenotypes have been defined. Most untreated individuals present with acute onset of striatal damage before age 3 (to 6) years, precipitated by infectious diseases, fever or surgery, resulting in irreversible, mostly dystonic movement disorder with limited life expectancy. In some patients, striatal damage develops insidiously. In recent years, the clinical phenotype has been extended by the finding of extrastriatal abnormalities and cognitive dysfunction, preferably in the high excreter group, as well as chronic kidney failure. Newborn screening is the prerequisite for pre-symptomatic start of metabolic treatment with low lysine diet, carnitine supplementation and intensified emergency treatment during catabolic episodes, which, in combination, have substantially improved neurologic outcome. In contrast, start of treatment after onset of symptoms cannot reverse existing motor dysfunction caused by striatal damage. Dietary treatment can be relaxed after the vulnerable period for striatal damage, that is, age 6 years. However, impact of dietary relaxation on long-term outcomes is still unclear. This third revision of evidence-based recommendations aims to re-evaluate previous recommendations (Boy et al., J Inherit Metab Dis, 2017;40(1):75-101; Kolker et al., J Inherit Metab Dis 2011;34(3):677-694; Kolker et al., J Inherit Metab Dis, 2007;30(1):5-22) and to implement new research findings on the evolving phenotypic diversity as well as the impact of non-interventional variables and treatment quality on clinical outcomes.

The indirect effect of positive aspects of caregiving on the relationship between cognitive decline and dementia caregiver burden.

BACKGROUND: Research has linked increased cognitive decline in a dementia care recipient to worsening caregiver burden, but the presence of positive aspects of caregiving is associated with better outcomes. As cognitive decline worsens, a lack of positive caregiving experiences could lead to burden for the caregiver. This study investigated relationships among dementia caregiver burden, cognitive decline, and positive aspects of caregiving in dementia, predicting an indirect effect of positive aspects of caregiving. METHODS: Data from 724 patients of an outpatient memory clinic in Ohio were examined and dyads included based on clinically supported patient diagnoses on the dementia spectrum. Caregivers completed the Zarit Burden Interview (ZBI) and Positive Aspects of Caregiving (PAC) measures. The Montreal Cognitive Assessment and Mini-Mental State Examination were used to estimate cognitive decline, standardized to create a single variable. Multiple potential covariates were considered for inclusion in the model. A cross-sectional mediation analysis using the Hayes PROCESS macro explored the presence of an indirect effect of PAC on the relationship between cognitive decline and ZBI using 5000 bootstrap samples. RESULTS: Only the potential covariate caregiver age was correlated with any of the primary variables; this variable was controlled in analyses. Significant relationships emerged between cognitive decline and ZBI (r = -0.12, P < 0.001), between PAC and ZBI (r = -0.23, P < 0.001), and between cognitive decline and PAC (r = -0.07, P < 0.05). An indirect effect of positive aspects of caregiving on the relationship between cognitive decline and ZBI was statistically significant (B = 0.0092, 95% bias-corrected confidence interval: 0.0008, 0.0185), accounting for 14.4% of the variance in the model. CONCLUSIONS: A lack of positive aspects of caregiving could be partially responsible for development of dementia caregiver burden as cognitive decline worsens. Longitudinal examination of these relationships is needed to understand causality fully. Findings may help healthcare providers tailor treatment to alleviate caregiver burden.

Genomic and biochemical analysis of repeatedly observed variants in DBT in individuals with maple syrup urine disease of Central American ancestry.

Maple syrup urine disease (MSUD) is an intoxication-type inherited metabolic disorder in which hyperleucinemia leads to brain swelling and death without treatment. MSUD is caused by branched-chain alpha-ketoacid dehydrogenase deficiency due to biallelic loss of the protein products from the genes BCKDHA, BCKDHB, or DBT, while a distinct but related condition is caused by loss of DLD. In this case series, eleven individuals with MSUD caused by two pathogenic variants in DBT are presented. All eleven individuals have a deletion of exon 2 (delEx2, NM_001918.3:c.48_171del); six individuals are homozygous and five individuals are compound heterozygous with a novel missense variant (NM_001918.5:c.916 T > C [p.Ser306Pro]) confirmed to be in trans. Western Blot indicates decreased amount of protein product in delEx2;c.916 T > C liver cells and absence of protein product in delEx2 homozygous hepatocytes. Ultrahigh performance liquid chromatography-tandem mass spectrometry demonstrates an accumulation of branched-chain amino acids and alpha-ketoacids in explanted hepatocytes. Individuals with these variants have a neonatal-onset, non-thiamine-responsive, classical form of MSUD. Strikingly, the entire cohort is derived from families who immigrated to the Washington, DC, metro area from Honduras or El Salvador suggesting the possibility of a founder effect.

Influence of early identification and therapy on long-term outcomes in early-onset MTHFR deficiency.

MTHFR deficiency is a severe inborn error of metabolism leading to impairment of the remethylation of homocysteine to methionine. Neonatal and early-onset patients mostly exhibit a life-threatening acute neurologic deterioration. Furthermore, data on early-onset patients' long-term outcomes are scarce. The aims of this study were (1) to study and describe the clinical and laboratory parameters of early-onset MTHFR-deficient patients (i.e., ≤3 months of age) and (2) to identify predictive factors for severe neurodevelopmental outcomes in a cohort with early and late onset MTHFR-deficient patients. To this end, we conducted a retrospective, multicentric, international cohort study on 72 patients with MTHFR deficiency from 32 international metabolic centres. Characteristics of the 32 patients with early-onset MTHFR deficiency were described at time of diagnosis and at the last follow-up visit. Logistic regression analysis was used to identify predictive factors of severe neurodevelopmental outcome in a broader set of patients with early and non-early-onset MTHFR deficiency. The majority of early-onset MTHFR-deficient patients (n = 32) exhibited neurologic symptoms (76%) and feeding difficulties (70%) at time of diagnosis. At the last follow-up visit (median follow-up time of 8.1 years), 76% of treated early-onset patients (n = 29) exhibited a severe neurodevelopmental outcome. Among the whole study population of 64 patients, pre-symptomatic diagnosis was independently associated with a significantly better neurodevelopmental outcome (adjusted OR 0.004, [0.002-0.232]; p = 0.003). This study provides evidence for benefits of pre-symptomatic diagnosis and appropriate therapeutic management, highlighting the need for systematic newborn screening for MTHFR deficiency and pre-symptomatic treatment that may improve outcome.

The Moderating Role of Pain Self-efficacy in the Relationships Among Caregiver Burden and Care Recipient Pain and Neuropsychiatric Symptoms in a Sample of Persons With Dementia.

Past research suggests relationships among dementia caregiver burden and care recipient pain and neuropsychiatric symptoms, but no prior work has examined the influence of pain self-efficacy on these associations. A sample of 502 dementia caregivers completed an online protocol assessing caregiver burden and care recipient neuropsychiatric symptoms, presence of pain, and pain self-efficacy in this cross-sectional, observational study. The indirect effect of neuropsychiatric symptoms on the relationship between pain and caregiver burden was significant. Pain self-efficacy significantly moderated the effect of pain on neuropsychiatric symptoms (P=0.04) and the direct association between pain and caregiver burden (P=0.004), but did not moderate the indirect effect. Future research should explore how pain influences neuropsychiatric symptoms, and whether improvement in pain self-efficacy in dementia care recipients attenuates the influence of pain on neuropsychiatric symptoms and caregiver burden in other samples.

Dysexecutive Behaviors Mediate the Relationship Between Functional Impairment and Caregiver Burden in Mild Cognitive Impairment.

Mild cognitive impairment (MCI) is often accompanied by executive dysfunction (ED), dysexecutive behaviors (DB), and functional impairment (FI). The respective contributions of ED, DB, and FI to caregiver burden in MCI are not well understood. The present study hypothesized that while all factors would predict caregiver burden in MCI, ED and family-reported DB would account for greater variance in caregiver burden and mediate the relationship between FI and caregiver burden. In our sample (n = 94), linear regression revealed that FI and DB predicted caregiver burden, but that DB predicted caregiver burden above and beyond the contribution of FI. DB mediated the relationship between FI and caregiver burden. These results add to a body of work demonstrating that presence of DB and FI are distressing to family members, even in mild disease stages. Because DB may account for the relationship between FI and caregiver burden, early identification of family members reporting DB in the person with MCI is imperative so that supports can be made available.

Factors of Dementia Caregiver Burden Differentially Contribute to Desire to Institutionalize.

The experience of dementia caregiver burden is multidimensional. Little is known about how different aspects of burden contribute to the consideration of moving a loved one to a structured living facility. In the present study, caregiver burden (Zarit Burden Interview; ZBI) and consideration of structured living arrangements (Desire to Institutionalize Scale; DIS) were self-reported by 339 caregivers. Exploratory factor analysis was used to determine the ZBI factor structure; these factors were then examined via hierarchical linear regression for prediction of DIS. Factor analysis indicated a 4-factor ZBI solution: Impact on Life, Guilt, Embarrassment/Frustration, and Escape/Uncertainty. Regression analyses indicated that only Escape/Uncertainty (p < .001) was associated with DIS. Of the 4 identified factors of caregiver burden, desire to escape the caregiving role was most related to consideration of structured living arrangements. Future work should explore longitudinal contribution of this factor to determine its role in actual changes made in living arrangements.

Specific agitation behaviours in dementia differentially contribute to aspects of caregiver burden.

BACKGROUND: Agitation is a common symptom in dementia and linked to caregiver burden, but both agitation and burden are multidimensional constructs. The current study sought to determine whether specific presentations of agitation differentially relate to aspects of caregiver burden. METHODS: Medical record data from an outpatient memory clinic were extracted for 609 persons with dementia, including caregiver-reported burden and care recipient agitation. RESULTS: Exploratory factor analysis yielded three domains of agitation on the Cohen Mansfield Agitation Inventory ('Physically Aggressive', 'Physically Non-Aggressive', 'Verbally Agitated') and four domains of burden on the Zarit Burden Interview ('Impact on Life', 'Guilt/Uncertainty', 'Embarrassment/Frustration', 'Overwhelm'). Regression analyses demonstrated all domains of agitation positively predicted overall burden. Regarding specific aspects of burden, Physically Aggressive behaviours predicted Embarrassment/Frustration. Physically Non-Aggressive behaviours predicted Impact on Life and Guilt/Uncertainty. Verbally Agitated behaviours predicted all burden dimensions. CONCLUSIONS: Results suggest specific aspects of agitation may differentially contribute to facets of caregiver burden.

A novel small molecule approach for the treatment of propionic and methylmalonic acidemias.

Propionic Acidemia (PA) and Methylmalonic Acidemia (MMA) are inborn errors of metabolism affecting the catabolism of valine, isoleucine, methionine, threonine and odd-chain fatty acids. These are multi-organ disorders caused by the enzymatic deficiency of propionyl-CoA carboxylase (PCC) or methylmalonyl-CoA mutase (MUT), resulting in the accumulation of propionyl-coenzyme A (P-CoA) and methylmalonyl-CoA (M-CoA in MMA only). Primary metabolites of these CoA esters include 2-methylcitric acid (MCA), propionyl-carnitine (C3), and 3-hydroxypropionic acid, which are detectable in both PA and MMA, and methylmalonic acid, which is detectable in MMA patients only (Chapman et al., 2012). We deployed liver cell-based models that utilized PA and MMA patient-derived primary hepatocytes to validate a small molecule therapy for PA and MMA patients. The small molecule, HST5040, resulted in a dose-dependent reduction in the levels of P-CoA, M-CoA (in MMA) and the disease-relevant biomarkers C3, MCA, and methylmalonic acid (in MMA). A putative working model of how HST5040 reduces the P-CoA and its derived metabolites involves the conversion of HST5040 to HST5040-CoA driving the redistribution of free and conjugated CoA pools, resulting in the differential reduction of the aberrantly high P-CoA and M-CoA. The reduction of P-CoA and M-CoA, either by slowing production (due to increased demands on the free CoA (CoASH) pool) or enhancing clearance (to replenish the CoASH pool), results in a net decrease in the CoA-derived metabolites (C3, MCA and MMA (MMA only)). A Phase 2 study in PA and MMA patients will be initiated in the United States.

Use of dexamethasone in idiopathic, acute pediatric rhabdomyolysis.

Current rhabdomyolysis treatment guidelines vary based on the etiology and diagnosis, yet many cases evade conclusive diagnosis. In these cases, treatment options remain largely limited to fluids and supportive therapy. We present two cases of acute rhabdomyolysis diagnosed in the emergency department: a 5-year-old boy with sudden onset bilateral flank pain, and a 13-year-old boy with 2-3 days of worsening pectoral and shoulder pain. Each patient had a prior similar episode requiring hospitalization in the past. The 5-year-old had no inciting trauma or trigger, medication use, or illness. The 13-year-old previously had an upper respiratory infection during the week prior and had been strenuously exercising at the time of onset. Genetic testing results were unknown for both patients during their hospitalizations, and insurance and other barriers led to delay. Later results for the first patient revealed a heterozygous deletion in intron 19 on the LPIN1 gene interpreted as a variant of unknown significance. During their hospitalizations, both children were started on intravenous (i.v.) fluids, and creatine kinase (CK) initially trended downward, but then began to rise or plateau. After reviewing the cases, prior literature, and anecdotal evidence of benefit from corticosteroid therapy in rhabdomyolysis with our consultant metabolic physicians, dexamethasone was initiated. In both patients, dexamethasone use correlated with relief of patient symptoms, significantly decreased CK value, and our ability to discharge these patients home quickly. Our cases, discussion, and literature review all lead to the consideration of the use of dexamethasone in conjunction with standard therapy for acute rhabdomyolysis.

Effects of triheptanoin (UX007) in patients with long-chain fatty acid oxidation disorders: Results from an open-label, long-term extension study.

Long-chain fatty acid oxidation disorders (LC-FAOD) are autosomal recessive conditions that impair conversion of long-chain fatty acids into energy, leading to significant clinical symptoms. Triheptanoin is a highly purified, 7-carbon chain triglyceride approved in the United States as a source of calories and fatty acids for treatment of pediatric and adult patients with molecularly confirmed LC-FAOD. CL202 is an open-label, long-term extension study evaluating triheptanoin (Dojolvi) safety and efficacy in patients with LC-FAOD. Patients rolled over from the CL201 triheptanoin clinical trial (rollover); were triheptanoin-naïve (naïve); or had participated in investigator-sponsored trials/expanded access programs (IST/other). Results focus on rollover and naïve groups, as pretreatment data allow comparison. Primary outcomes were annual rate and duration of major clinical events (MCEs; rhabdomyolysis, hypoglycemia, and cardiomyopathy events). Seventy-five patients were enrolled (24 rollover, 20 naïve, 31 IST/other). Mean study duration was 23.0 months for rollover, 15.7 months for naïve, and 34.7 months for IST/other. In the rollover group, mean annualized MCE rate decreased from 1.76 events/year pre-triheptanoin to 0.96 events/year with triheptanoin (P = .0319). Median MCE duration was reduced by 66%. In the naïve group, median annualized MCE rate decreased from 2.33 events/year pre-triheptanoin to 0.71 events/year with triheptanoin (P = .1072). Median MCE duration was reduced by 80%. The most common related adverse events (AEs) were diarrhea, abdominal pain/discomfort, and vomiting, most mild to moderate. Three patients had serious AEs (diverticulitis, ileus, rhabdomyolysis) possibly related to drug; all resolved. Two patients had AEs leading to death; neither drug related. Triheptanoin reduced rate and duration of MCEs. Safety was consistent with previous observations.

Guidelines for the diagnosis and management of methylmalonic acidaemia and propionic acidaemia: First revision.

Isolated methylmalonic acidaemia (MMA) and propionic acidaemia (PA) are rare inherited metabolic diseases. Six years ago, a detailed evaluation of the available evidence on diagnosis and management of these disorders has been published for the first time. The article received considerable attention, illustrating the importance of an expert panel to evaluate and compile recommendations to guide rare disease patient care. Since that time, a growing body of evidence on transplant outcomes in MMA and PA patients and use of precursor free amino acid mixtures allows for updates of the guidelines. In this article, we aim to incorporate this newly published knowledge and provide a revised version of the guidelines. The analysis was performed by a panel of multidisciplinary health care experts, who followed an updated guideline development methodology (GRADE). Hence, the full body of evidence up until autumn 2019 was re-evaluated, analysed and graded. As a result, 21 updated recommendations were compiled in a more concise paper with a focus on the existing evidence to enable well-informed decisions in the context of MMA and PA patient care.

Development of an assessment measure for sexual disinhibition in dementia.

OBJECTIVE: Sexual disinhibition (SD), a neuropsychiatric symptom characterized by sexually inappropriate comments and/or behaviors, remains under identified in dementia, possibly due to a lack of standardized assessment methods. A recent systematic review of measures used to assess SD proposed four behavioral domains and identified the need for a population-specific measure. The present study addressed this by examining the underlying factor structure of SD to create a new caregiver-report measure. METHODS: Dementia caregivers (n = 622) recruited online were randomly assigned to Initial Validation (n = 311) or Cross-Validation (n = 311) groups. RESULTS: Initial Validation revealed five behavioral domains that served as provisional scales for cross-validation, leading to measure development. CONCLUSIONS: The current study is the first to statistically evaluate the underlying factor structure of SD, resulting in a new measure that can help better characterize and identify SD.

Genetic considerations for adults with congenital heart disease.

Congenital heart disease (CHD) remains the most common birth defect, with an estimated incidence of approximately 1% of all births. The population of adults with CHD is growing rapidly with advances in medical care. Overall survival to adulthood in the current era estimated to exceed 90%. Genetic causes of CHD can be classified into several broad categories: (a) chromosomal aneuploidy, (b) large chromosomal deletion or duplication, (c) single gene mutation, and (d) copy number variation. However, only 20-30% of CHD cases have an established etiology characterized by either genetic abnormalities or environmental factors. The role of genetics in the field of adult CHD is only increasing. More adult patients with CHD are seeking genetic counseling to understand the etiology of their underlying CHD and the risks to future offspring. A multidisciplinary approach is essential to provide appropriate counseling to patients regarding indications for genetic testing and interpretations of results. Novel advances with precision medicine may soon enable clinicians to individualize therapies for a comprehensive approach to the care of adult patients with CHD.

De novo SMARCA2 variants clustered outside the helicase domain cause a new recognizable syndrome with intellectual disability and blepharophimosis distinct from Nicolaides-Baraitser syndrome.

PURPOSE: Nontruncating variants in SMARCA2, encoding a catalytic subunit of SWI/SNF chromatin remodeling complex, cause Nicolaides-Baraitser syndrome (NCBRS), a condition with intellectual disability and multiple congenital anomalies. Other disorders due to SMARCA2 are unknown. METHODS: By next-generation sequencing, we identified candidate variants in SMARCA2 in 20 individuals from 18 families with a syndromic neurodevelopmental disorder not consistent with NCBRS. To stratify variant interpretation, we functionally analyzed SMARCA2 variants in yeasts and performed transcriptomic and genome methylation analyses on blood leukocytes. RESULTS: Of 20 individuals, 14 showed a recognizable phenotype with recurrent features including epicanthal folds, blepharophimosis, and downturned nasal tip along with variable degree of intellectual disability (or blepharophimosis intellectual disability syndrome [BIS]). In contrast to most NCBRS variants, all SMARCA2 variants associated with BIS are localized outside the helicase domains. Yeast phenotype assays differentiated NCBRS from non-NCBRS SMARCA2 variants. Transcriptomic and DNA methylation signatures differentiated NCBRS from BIS and those with nonspecific phenotype. In the remaining six individuals with nonspecific dysmorphic features, clinical and molecular data did not permit variant reclassification. CONCLUSION: We identified a novel recognizable syndrome named BIS associated with clustered de novo SMARCA2 variants outside the helicase domains, phenotypically and molecularly distinct from NCBRS.

Biochemical and anaplerotic applications of in vitro models of propionic acidemia and methylmalonic acidemia using patient-derived primary hepatocytes.

Propionic acidemia (PA) and methylmalonic acidemia (MMA) are autosomal recessive disorders of propionyl-CoA (P-CoA) catabolism, which are caused by a deficiency in the enzyme propionyl-CoA carboxylase or the enzyme methylmalonyl-CoA (MM-CoA) mutase, respectively. The functional consequence of PA or MMA is the inability to catabolize P-CoA to MM-CoA or MM-CoA to succinyl-CoA, resulting in the accumulation of P-CoA and other metabolic intermediates, such as propionylcarnitine (C3), 3-hydroxypropionic acid, methylcitric acid (MCA), and methylmalonic acid (only in MMA). P-CoA and its metabolic intermediates, at high concentrations found in PA and MMA, inhibit enzymes in the first steps of the urea cycle as well as enzymes in the tricarboxylic acid (TCA) cycle, causing a reduction in mitochondrial energy production. We previously showed that metabolic defects of PA could be recapitulated using PA patient-derived primary hepatocytes in a novel organotypic system. Here, we sought to investigate whether treatment of normal human primary hepatocytes with propionate would recapitulate some of the biochemical features of PA and MMA in the same platform. We found that high levels of propionate resulted in high levels of intracellular P-CoA in normal hepatocytes. Analysis of TCA cycle intermediates by GC-MS/MS indicated that propionate may inhibit enzymes of the TCA cycle as shown in PA, but is also incorporated in the TCA cycle, which does not occur in PA. To better recapitulate the disease phenotype, we obtained hepatocytes derived from livers of PA and MMA patients. We characterized the PA and MMA donors by measuring key proximal biomarkers, including P-CoA, MM-CoA, as well as clinical biomarkers propionylcarnitine-to-acetylcarnitine ratios (C3/C2), MCA, and methylmalonic acid. Additionally, we used isotopically-labeled amino acids to investigate the contribution of relevant amino acids to production of P-CoA in models of metabolic stability or acute metabolic crisis. As observed clinically, we demonstrated that the isoleucine and valine catabolism pathways are the greatest sources of P-CoA in PA and MMA donor cells and that each donor showed differential sensitivity to isoleucine and valine. We also studied the effects of disodium citrate, an anaplerotic therapy, which resulted in a significant increase in the absolute concentration of TCA cycle intermediates, which is in agreement with the benefit observed clinically. Our human cell-based PA and MMA disease models can inform preclinical drug discovery and development where mouse models of these diseases are inaccurate, particularly in well-described species differences in branched-chain amino acid catabolism.

Mitochondrial energetic impairment in a patient with late-onset glutaric acidemia Type 2.

Glutaric acidemia type 2 (GA2), also called multiple acyl-CoA dehydrogenase deficiency, is an autosomal recessive disorder of fatty acid, amino acid, and choline metabolism resulting in excretion of multiple organic acids and glycine conjugates as well as elevation of various plasma acylcarnitine species (C4-C18). It is caused by mutations in the ETFA, ETFB, or ETFDH genes which are involved in the transfer of electrons from 11 flavin-containing dehydrogenases to Coenzyme Q10 (CoQ10 ) of the mitochondrial electron transport chain (ETC). We report a patient who was originally reported as the first case with primary myopathic CoQ10 deficiency when he presented at 11.5 years with exercise intolerance and myopathy that improved after treatment with ubiquinone and carnitine. At age 23, his symptoms relapsed despite increasing doses of ubiquinone and he was shown to have biallelic mutations in the ETFDH gene. Treatment with riboflavin was started and ubiquinone was changed to ubiquinol. After 4 months, the patient recovered his muscle strength with normalization of laboratory exams and exercise tolerance. Functional studies on fibroblasts revealed decreased levels of ETFDH as well as of very long-chain acyl-CoA dehydrogenase and trifunctional protein α. In addition, the mitochondrial mass was decreased, with increased formation of reactive oxygen species and oxygen consumption rate, but with a decreased spared respiratory capacity, and decreased adenosine triphosphate level. These findings of widespread dysfunction of fatty acid oxidation and ETC enzymes support the impairment of a larger mitochondrial ETC supercomplex in our patient.

The Role of Sexual Disinhibition to Predict Caregiver Burden and Desire to Institutionalize Among Family Dementia Caregivers.

Neuropsychiatric symptoms in dementia are associated with greater caregiver burden and desire to institutionalize, though previous work largely examines the cumulative effects of many behavioral symptoms. Sexual disinhibition could be particularly stressful due to stigma attached to these behaviors. Links between care recipient sexual disinhibition, caregiver burden, and caregiver desire to institutionalize were examined by analyzing cross-sectional data from 730 family caregivers recruited online. Caregiver burden, caregiver desire to institutionalize, and neuropsychiatric symptoms, including sexual disinhibition, were assessed via caregiver report. Burden (P < .001) and desire to institutionalize (P = .008) were greater among caregivers who endorsed sexual disinhibition. Sexual disinhibition uniquely predicted desire to institutionalize after accounting for presence (P = .02) and severity (P = .03) of other neuropsychiatric symptoms. A similar pattern was seen for burden (presence P < .04; severity P = .06), and follow-up analyses revealed caregiver burden mediated the relationship between care recipient sexual disinhibition and caregiver desire to institutionalize (presence bias-corrected 95% confidence intervals [BCa 95% CI] [0.003, 0.08], severity BCa 95% CI [0.007, 0.06]). Sexual disinhibition appears to be a particularly difficult neuropsychiatric symptom for the family caregiver, contributing to desire to institutionalize via caregiver burden.