Cardiomyopathy and carnitine deficiency

A Rare Treatable Cause of Cardiomyopathy: Primary Carnitine Deficiency

Introduction

Primary carnitine deficiency (PCD) is a rare autosomal recessive disorder caused by loss of function mutations in the solute carrier family 22 member 5 (SLC22A5) gene that encodes a high-affinity sodium-ion-dependent organic cation transporter protein (OCTN2). Carnitine deficiency can result in acute metabolic decompensation or, in a more insidious presentation, cardiomyopathy. Cardiomyopathy associated with PCD often presents with life-threatening heart failure. This presentation also usually includes skeletal muscle myopathy. Early recognition of this disorder and treatment with carnitine can avoid life-threatening complications related to cardiomyopathy.

Case Presentation

Herein, we present a 10-month-old male patient with PCD, which was diagnosed while investigating the etiology of dilated cardiomyopathy and confirmed by molecular genetic analysis.

Conclusion

Homozygous c.254_265 insGGCTCGCCACC (p.I89Gfs) pathogenic variant of the SLC22A5 gene was detected. With oral L-carnitine supplementation, the free carnitine level increased up to 14 μmol/L and the symptoms disappeared. LVEF increased by 45-70%. We would like to emphasize that this problem is a combination of the metabolic decompensation and the cardiac phenotypes, which are usually separated to either phenotype.

Targeting mitochondrial impairment for the treatment of cardiovascular diseases: From hypertension to ischemia-reperfusion injury, searching for new pharmacological targets

Mitochondria and mitochondrial proteins represent a group of promising pharmacological target candidates in the search of new molecular targets and drugs to counteract the onset of hypertension and more in general cardiovascular diseases (CVDs). Indeed, several mitochondrial pathways result impaired in CVDs, showing ATP depletion and ROS production as common traits of cardiac tissue degeneration. Thus, targeting mitochondrial dysfunction in cardiomyocytes can represent a successful strategy to prevent heart failure. In this context, the identification of new pharmacological targets among mitochondrial proteins paves the way for the design of new selective drugs. Thanks to the advances in omics approaches, to a greater availability of mitochondrial crystallized protein structures and to the development of new computational approaches for protein 3D-modelling and drug design, it is now possible to investigate in detail impaired mitochondrial pathways in CVDs. Furthermore, it is possible to design new powerful drugs able to hit the selected pharmacological targets in a highly selective way to rescue mitochondrial dysfunction and prevent cardiac tissue degeneration. The role of mitochondrial dysfunction in the onset of CVDs appears increasingly evident, as reflected by the impairment of proteins involved in lipid peroxidation, mitochondrial dynamics, respiratory chain complexes, and membrane polarization maintenance in CVD patients. Conversely, little is known about proteins responsible for the cross-talk between mitochondria and cytoplasm in cardiomyocytes. Mitochondrial transporters of the SLC25A family, in particular, are responsible for the translocation of nucleotides (e.g., ATP), amino acids (e.g., aspartate, glutamate, ornithine), organic acids (e.g. malate and 2-oxoglutarate), and other cofactors (e.g., inorganic phosphate, NAD⁺, FAD, carnitine, CoA derivatives) between the mitochondrial and cytosolic compartments. Thus, mitochondrial transporters play a key role in the mitochondria-cytosol cross-talk by leading metabolic pathways such as the malate/aspartate shuttle, the carnitine shuttle, the ATP export from mitochondria, and the regulation of permeability transition pore opening. Since all these pathways are crucial for maintaining healthy cardiomyocytes, mitochondrial carriers emerge as an interesting class of new possible pharmacological targets for CVD treatments.

Infantile primary carnitine deficiency: A severe cardiac presentation unresponsive to carnitine supplementation

Primary carnitine deficiency (PCD) is an inherited disease of fatty acid beta-oxidation with autosomal recessive inheritance. The disease manifests as metabolic decompensation with hypoketotic hypoglycaemia associated with cardiomyopathy, hepatomegaly, rhabdomyolysis, and seizures. Various outcomes are described from asymptomatic adults to dramatic sudden infant death syndrome cases. We present a severe case of PCD decompensation in an 18-week-old female. She presented with hypotonia, moaning, diarrhea, and vomiting at the pediatric emergency. Initially suspected as intracranial hypertension, the clinical condition evolved rapidly and caused a reversible cardiac arrest with profound hypoglycemia. Despite carnitine supplementation, she succumbed from cardiac arrhythmia and multivisceral failure 4 days after admission. The genetic analyses showed a PCD with biallelic pathogenic variants of SLC22A5 gene. The case report is notable for the severity of the cardiac damage possibly favored by maternal carnitine deficiency during pregnancy. The analysis of previously published PCD cases highlights (i) the importance of having large access to emergency biochemical tests for early therapeutic care although the disease has unpredictable severity and (ii) the fact that the clinical outcome remains unpredictable if carnitine treatment is initiated late.

Tandem Mass Spectrometry Screening for Inborn Errors of Metabolism in Newborns and High-Risk Infants in Southern China: Disease Spectrum and Genetic Characteristics in a Chinese Population

Inborn errors of metabolism (IEMs) often causing progressive and irreversible neurological damage, physical and intellectual development lag or even death, and serious harm to the family and society. The screening of neonatal IEMs by tandem mass spectrometry (MS/MS) is an effective method for early diagnosis and presymptomatic treatment to prevent severe permanent sequelae and death. A total of 111,986 healthy newborns and 7,461 hospitalized high-risk infants were screened for IEMs using MS/MS to understand the characteristics of IEMs and related gene mutations in newborns and high-risk infants in Liuzhou. Positive samples were analyzed by Sanger sequencing or next-generation sequencing. The results showed that the incidence of IEMs in newborns in the Liuzhou area was 1/3,733, and the incidence of IEMs in high-risk infants was 1/393. Primary carnitine deficiency (1/9,332), phenylketonuria (1/18,664), and isovaleric acidemia (1/37,329) ranked the highest in neonates, while citrullinemia type II ranked the highest in high-risk infants (1/1,865). Further, 56 mutations of 17 IEMs-related genes were found in 49 diagnosed children. Among these, HPD c.941T > C, CBS c.1465C > T, ACADS c.337G > A, c.1195C > T, ETFA c.737G > T, MMACHC 1076bp deletion, PCCB c.132-134delGACinsAT, IVD c.548C > T, c.757A > G, GCDH c.1060G > T, and HMGCL c.501C > G were all unreported variants. Some related hotspot mutations were found, including SLC22A5 c.51C > G, PAH c.1223G > A, IVD c.1208A > G, ACADS c.625G > A, and GCDH c.532G > A. These results show that the overall incidence of IEMs in the Liuzhou area is high. Hence, the scope of IEMs screening and publicity and education should be expanded for a clear diagnosis in the early stage of the disease.

Maternal Primary Carnitine Deficiency and a Novel Solute Carrier Family 22 Member 5 (SLC22A5) Mutation

Primary carnitine deficiency (PCD) is a rare autosomal recessive disorder caused by loss of function mutations in the solute carrier family 22 member 5 (SLC22A5) gene that encodes a high-affinity sodium-ion–dependent organic cation transporter protein (OCTN2). Reduced carnitine transport results in diminished fatty acid oxidation in heart and skeletal muscle and carnitine wasting in urine. We present a case of PCD diagnosed in an adult female after a positive newborn screen (NBS) for PCD that was not confirmed on follow-up testing. The mother was referred for evaluation of persistent fatigue and possible hypothyroidism even though all measurements of thyroid-stimulating hormone were well within the range of 0.4 to 2.5 mIU/L expected for reproductive-age women. She was found to have unequivocally low levels of both total carnitine and carnitine esters, and genetic testing revealed compound heterozygosity for 2 SLC22A5 mutations. One mutation (c.34G>A [p.Gly12Ser]) is a known missense mutation with partial OCTN2 activity, but the other mutation (c.41G>A [p.Trp14Ter]) is previously unreported and results in a premature stop codon and truncated OCTN2. This case illustrates that some maternal inborn errors of metabolism can be identified by NBS and that maternal carnitine levels should be checked after a positive NBS test for PCD.

Gene spectrum and clinical traits of 10 patients with primary carnitine deficiency

BACKGROUND

Rare studies focused on the tandem mass spectrometry (MS/MS) findings for the primary carnitine deficiency (PCD) in the neonates in China mainland. In this study, we aim to analyze the gene mutation spectrum of PCD in Fujian Province in China mainland.

METHODS

Primary carnitine deficiency (PCD) samples used in this study were selected from 95,453 cases underwent neonatal screening between May 2015 and February 2020. SLC22A5 gene sequencing was performed on the neonates and their parents with C0 level of less than 8.8 μmol/L.

RESULTS

Ten patients (male: 7; female: 3) were finally included in this study. Among these patients, nine were neonates, and one was maternal decline of C0 of less than 8.8 μmol/L. The maternal case showed two types of mutations of SLC22A5 including c.760C>T(p.R254*) and c.1400C>G(p.S467C). The other nine neonates showed compound mutations involving nine types in 18 sites, among which two mutations [i.e., c.37G>T(p.E13*) and c.694A>G(p.T232A)] were novel that had never been reported before. Bioinformatic analysis indicated that c.37G>T(p.E13*) was a pathogenic mutation, while the c.694A>G (p.T232A) was considered to be likely pathogenic.

CONCLUSION

MS/MS screening on PCD contributed to the early diagnosis and screening. In addition, SLC22A5 gene mutation analysis contributed to the PCD screening.

Organic Cation Transporters in Health and Disease

The organic cation transporters (OCTs) OCT1, OCT2, OCT3, novel OCT (OCTN)1, OCTN2, multidrug and toxin exclusion (MATE)1, and MATE kidney-specific 2 are polyspecific transporters exhibiting broadly overlapping substrate selectivities. They transport organic cations, zwitterions, and some uncharged compounds and operate as facilitated diffusion systems and/or antiporters. OCTs are critically involved in intestinal absorption, hepatic uptake, and renal excretion of hydrophilic drugs. They modulate the distribution of endogenous compounds such as thiamine, L-carnitine, and neurotransmitters. Sites of expression and functions of OCTs have important impact on energy metabolism, pharmacokinetics, and toxicity of drugs, and on drug-drug interactions. In this work, an overview about the human OCTs is presented. Functional properties of human OCTs, including identified substrates and inhibitors of the individual transporters, are described. Sites of expression are compiled, and data on regulation of OCTs are presented. In addition, genetic variations of OCTs are listed, and data on their impact on transport, drug treatment, and diseases are reported. Moreover, recent data are summarized that indicate complex drug-drug interaction at OCTs, such as allosteric high-affinity inhibition of transport and substrate dependence of inhibitor efficacies. A hypothesis about the molecular mechanism of polyspecific substrate recognition by OCTs is presented that is based on functional studies and mutagenesis experiments in OCT1 and OCT2. This hypothesis provides a framework to imagine how observed complex drug-drug interactions at OCTs arise. Finally, preclinical in vitro tests that are performed by pharmaceutical companies to identify interaction of novel drugs with OCTs are discussed. Optimized experimental procedures are proposed that allow a gapless detection of inhibitory and transported drugs.

Carnitine Inborn Errors of Metabolism

Carnitine plays essential roles in intermediary metabolism. In non-vegetarians, most of carnitine sources (~75%) are obtained from diet whereas endogenous synthesis accounts for around 25%. Renal carnitine reabsorption along with dietary intake and endogenous production maintain carnitine homeostasis. The precursors for carnitine biosynthesis are lysine and methionine. The biosynthetic pathway involves four enzymes: 6-N-trimethyllysine dioxygenase (TMLD), 3-hydroxy-6-N-trimethyllysine aldolase (HTMLA), 4-N-trimethylaminobutyraldehyde dehydrogenase (TMABADH), and γ-butyrobetaine dioxygenase (BBD). OCTN2 (organic cation/carnitine transporter novel type 2) transports carnitine into the cells. One of the major functions of carnitine is shuttling long-chain fatty acids across the mitochondrial membrane from the cytosol into the mitochondrial matrix for β-oxidation. This transport is achieved by mitochondrial carnitine–acylcarnitine cycle, which consists of three enzymes: carnitine palmitoyltransferase I (CPT I), carnitine-acylcarnitine translocase (CACT), and carnitine palmitoyltransferase II (CPT II). Carnitine inborn errors of metabolism could result from defects in carnitine biosynthesis, carnitine transport, or mitochondrial carnitine–acylcarnitine cycle. The presentation of these disorders is variable but common findings include hypoketotic hypoglycemia, cardio(myopathy), and liver disease. In this review, the metabolism and homeostasis of carnitine are discussed. Then we present details of different inborn errors of carnitine metabolism, including clinical presentation, diagnosis, and treatment options. At the end, we discuss some of the causes of secondary carnitine deficiency.

First Case Report of Primary Carnitine Deficiency Manifested as Intellectual Disability and Autism Spectrum Disorder

Systemic primary carnitine deficiency (PCD) is a genetic disorder caused by decreased or absent organic cation transporter type 2 (OCTN2) carnitine transporter activity, resulting in low serum carnitine levels and decreased carnitine accumulation inside cells. In early life, PCD is usually diagnosed as a metabolic decompensation, presenting as hypoketotic hypoglycemia, Reye syndrome, or sudden infant death; in childhood, PCD presents with skeletal or cardiac myopathy. However, the clinical presentation of PCD characterized by autism spectrum disorder (ASD) with intellectual disability (ID) has seldom been reported in the literature. In this report, we describe the clinical features of a seven-year-old girl diagnosed with PCD who presented atypical features of the disease, including a developmental delay involving language skills, concentration, and attention span, as well as autistic features and brain alterations apparent in magnetic resonance imaging. We aim to highlight the difficulties related to the diagnostic and therapeutic approaches used to diagnose such patients. The case reported here presented typical signs of PCD, including frequent episodes of hypoglycemia, generalized muscle weakness, decreased muscle mass, and physical growth deficits. A molecular genetic study confirmed the definitive diagnosis of the disease (c.1345T>G (p.Y449D)) in gene SLC22A5, located in exon 8. PCD can be accompanied by less common clinical signs, which may delay its diagnosis because the resulting global clinical picture can closely resemble other metabolic disorders. In this case, the patient was prescribed a carnitine-enriched diet, as well as oral carnitine at a dose of 100 mg/kg/day. PCD has a better prognosis if it is diagnosed and treated early; however, a high level of clinical suspicion is required for its timely and accurate diagnosis.

The effect of L-carnitine on inflammatory mediators: a systematic review and meta-analysis of randomized clinical trials

AIM AND BACKGROUND

Reducing inflammation by nutritional supplements may help to reduce the risk of many chronic diseases. Our aim in this meta-analysis was to determine the effect of L-carnitine on inflammatory mediators including C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6).

METHODS

Our systematic search to find relevant randomized clinical trials (RCTs) was performed up to October 2018 using ISI Web of Science, Google Scholar, PubMed/Medline, and SCOPUS. In this meta-analysis, the weighted mean differences (WMD) with standard errors (SE) were used to pool the data. WMD was calculated by subtracting change-from-baseline mean values in the control group from change-from-baseline mean values in the intervention group in each study. To identify heterogeneity among studies, the I² statistic was employed. The protocol was registered with PROSPERO (No. CRD42019116695).

RESULTS

Thirteen articles were included in our systematic review and meta-analysis. The results of the meta-analysis indicated that L-carnitine supplementation was significantly associated with lower levels of CRP in comparison to controls (WMD = -1.23 mg/L; 95% CI: -1.73, -0.72 mg/dL; P < 0.0001). Also, a slight but statistically significant decrease was observed in IL-6 and TNF-α levels (WMD = -0.85 pg/dL; 95% CI: -1.38, -0.32 pg/dL; P = 0.002 and WMD = -0.37 pg/dL; 95% CI: -0.68, -0.06 pg/dL; P = 0.018, respectively).

CONCLUSION

Our results indicate that L-carnitine reduced inflammatory mediators, especially in studies with a duration of more than 12 weeks. Further studies with different doses and intervention durations and separately in men and women are necessary.

Carnitine deficiency in epileptic children treated with a diversity of anti-epileptic regimens

Background

Carnitine deficiency is relatively common in epileptic patients. The risk factors reported include the combination of valproic acid with other antiepileptic drugs (AEDs), young age, multiple neurologic disabilities, non-ambulatory status, and being underweight.

Objectives

To study the level of carnitine deficiency and its associated risk factors among a group of children with idiopathic epilepsy treated with different AEDs.

Patients and methods

Fifty children with idiopathic epilepsy and 40 age-matched controls were enrolled. For all, serum carnitine level was measured by enzyme-linked immune sorbent assay (ELISA).

Results

The mean carnitine level was lower in cases compared to controls (p = 0.04). Patients receiving monotherapy treatment had a high percentage of carnitine deficiency compared to controls (p = 0.04). Patients receiving valproate with other AEDs had a lower level of carnitine compared to controls (p = 0.03). The age of the patients, the duration of treatment, and the doses of different AEDs were not risk factors for carnitine deficiency.

Conclusions

Carnitine deficiency is common in our population, and the use of valproate with other AEDs is considered the most important risk factor for it in epileptic children.

Functional and molecular studies in primary carnitine deficiency

Primary carnitine deficiency is caused by a defect in the OCTN2 carnitine transporter encoded by the SLC22A5 gene. It can cause hypoketotic hypoglycemia or cardiomyopathy in children, and sudden death in children and adults. Fibroblasts from affected patients have reduced carnitine transport. We evaluated carnitine transport in fibroblasts from 358 subjects referred for possible carnitine deficiency. Carnitine transport was reduced to 20% or less of normal in fibroblasts of 140 out of 358 subjects. Sequencing of the 10 exons and flanking regions of the SLC22A5 gene in 95 out of 140 subjects identified causative variants in 84% of the alleles. The missense variants identified in our patients and others previously reported (n = 92) were expressed in CHO cells. Carnitine transport was impaired by 73 out of 92 variants expressed. Prediction algorithms (Polyphen-2, SIFT) correctly predicted the functional effects of expressed variants in about 80% of cases. These results indicate that mutations in the coding region of the SLC22A5 gene cannot be identified in about 16% of the alleles causing primary carnitine deficiency. Prediction algorithms failed to determine the functional effects of amino acid substitutions in this transmembrane protein in about 20% of cases. Therefore, functional studies in fibroblasts remain the best strategy to confirm or exclude a diagnosis of primary carnitine deficiency.

Clinical features and genotyping of patients with primary carnitine deficiency identified by newborn screening

BACKGROUND

The objective of the study was to investigate clinical and gene mutation characteristics of primary carnitine deficiency (PCD) patients identified by newborn screening using tandem mass spectrometry (MS/MS).

METHODS

Tandem mass spectrometry (MS/MS) was applied to screen inherited metabolic disease and seven patients with PCD were diagnosed among 62,568 samples. The SLC22A5 gene was detected by using diagnosis panel of genetic and metabolic diseases based on Ion Torrent Semiconductor Sequencing Technology.

RESULTS

The initial free carnitine (C0) concentrations of the patients were 6.43±1.36 μmol/L, and the recall screening concentrations were 5.59±0.89 μmol/L. The patients were treated with oral carnitine, so the levels after treatment were 20.24±3.88 μmol/L. All patients had two pathogenic mutation alleles.

CONCLUSIONS

The combined application of MS/MS and a next generation sequencing panel could be used for the accurate diagnosis of PCD. The results of genetic diagnosis can guide the assisted reproductive treatment. The prognosis of PCD patients is good after early treatment.

Significance of l-carnitine for human health

Carnitine acyltransferases catalyze the reversible transfer of acyl groups from acyl-coenzyme A esters to l-carnitine, forming acyl-carnitine esters that may be transported across cell membranes. l-Carnitine is a wáter-soluble compound that humans may obtain both by food ingestion and endogenous synthesis from trimethyl-lysine. Most l-carnitine is intracellular, being present predominantly in liver, skeletal muscle, heart and kidney. The organic cation transporter-2 facilitates l-carnitine uptake inside cells. Congenital dysfunction of this transporter causes primary l-carnitine deficiency. Carnitine acetyltransferase is involved in the export of excess acetyl groups from the mitochondria and in acetylation reactions that regulate gene transcription and enzyme activity. Carnitine octanoyltransferase is a peroxysomal enzyme required for the complete oxidation of very long-chain fatty acids and phytanic acid, a branched-chain fatty acid. Carnitine palmitoyltransferase-1 is a transmembrane protein located on the outer mitochondrial membrane where it catalyzes the conversion of acyl-coenzyme A esters to acyl-carnitine esters. Carnitine acyl-carnitine translocase transports acyl-carnitine esters across the inner mitochondrial membrane in exchange for free l-carnitine that exits the mitochondrial matrix. Carnitine palmitoyltransferase-2 is anchored on the matrix side of the inner mitochondrial membrane, where it converts acyl-carnitine esters back to acyl-coenzyme A esters, which may be used in metabolic pathways, such as mitochondrial β-oxidation. l-Carnitine enhances nonoxidative glucose disposal under euglycemic hyperinsulinemic conditions in both healthy individuals and patients with type 2 diabetes, suggesting that l-carnitine strengthens insulin effect on glycogen storage. The plasma level of acyl-carnitine esters, primarily acetyl-carnitine, increases during diabetic ketoacidosis, fasting, and physical activity, particularly high-intensity exercise. Plasma concentration of free l-carnitine decreases simultaneously under these conditions. © 2017 IUBMB Life, 69(8):578-594, 2017.

Recent advance in the pharmacogenomics of human Solute Carrier Transporters (SLCs) in drug disposition

Drug pharmacokinetics is influenced by the function of metabolising enzymes and influx/efflux transporters. Genetic variability of these genes is known to impact on clinical therapies. Solute Carrier Transporters (SLCs) are the primary influx transporters responsible for the cellular uptake of drug molecules, which consequently, impact on drug efficacy and toxicity. The Organic Anion Transporting Polypeptides (OATPs), Organic Anion Transporters (OATs) and Organic Cation Transporters (OCTs/OCTNs) are the most important SLCs involved in drug disposition. The information regarding the influence of SLC polymorphisms on drug pharmacokinetics is limited and remains a hot topic of pharmaceutical research. This review summarises the recent advance in the pharmacogenomics of SLCs with an emphasis on human OATPs, OATs and OCTs/OCTNs. Our current appreciation of the degree of variability in these transporters may contribute to better understanding the inter-patient variation of therapies and thus, guide the optimisation of clinical treatments.

The effect of (L-)carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials

This study provides a systematic review and meta-analysis of randomized controlled trials, which have examined the effect of the carnitine on adult weight loss. Relevant studies were identified by systematic search of PubMed, Embase, Cochrane Central Register of Controlled Trials and reference lists of relevant marker studies. Nine studies (total n = 911) of adequate methodological quality were included in the review. Trials with mean difference (MD) of 95% confidence interval (CI) were pooled using random effect model. Results from meta-analysis of eligible trials revealed that subjects who received carnitine lost significantly more weight (MD: -1.33 kg; 95% CI: -2.09 to -0.57) and showed a decrease in body mass index (MD: -0.47 kg m(-2) ; 95% CI: -0.88 to -0.05) compared with the control group. The results of meta-regression analysis of duration of consumption revealed that the magnitude of weight loss resulted by carnitine supplementation significantly decreased over time (p = 0.002). We conclude that receiving the carnitine resulted in weight loss. Using multiple-treatments meta-analysis of the drugs and non-pharmacotherapy options seem to be insightful areas for research. © 2016 World Obesity.

Carnitine transport and fatty acid oxidation

Carnitine is essential for the transfer of long-chain fatty acids across the inner mitochondrial membrane for subsequent β-oxidation. It can be synthesized by the body or assumed with the diet from meat and dairy products. Defects in carnitine biosynthesis do not routinely result in low plasma carnitine levels. Carnitine is accumulated by the cells and retained by kidneys using OCTN2, a high affinity organic cation transporter specific for carnitine. Defects in the OCTN2 carnitine transporter results in autosomal recessive primary carnitine deficiency characterized by decreased intracellular carnitine accumulation, increased losses of carnitine in the urine, and low serum carnitine levels. Patients can present early in life with hypoketotic hypoglycemia and hepatic encephalopathy, or later in life with skeletal and cardiac myopathy or sudden death from cardiac arrhythmia, usually triggered by fasting or catabolic state. This disease responds to oral carnitine that, in pharmacological doses, enters cells using the amino acid transporter B(0,+). Primary carnitine deficiency can be suspected from the clinical presentation or identified by low levels of free carnitine (C0) in the newborn screening. Some adult patients have been diagnosed following the birth of an unaffected child with very low carnitine levels in the newborn screening. The diagnosis is confirmed by measuring low carnitine uptake in the patients' fibroblasts or by DNA sequencing of the SLC22A5 gene encoding the OCTN2 carnitine transporter. Some mutations are specific for certain ethnic backgrounds, but the majority are private and identified only in individual families. Although the genotype usually does not correlate with metabolic or cardiac involvement in primary carnitine deficiency, patients presenting as adults tend to have at least one missense mutation retaining residual activity. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.

Identification of SLC22A5 Gene Mutation in a Family with Carnitine Uptake Defect

Primary systemic carnitine deficiency is caused by homozygous or compound heterozygous mutation in the SLC22A5 gene on chromosome 5q31. The most common presentations are in infancy and early childhood with either metabolic decompensation or cardiac and myopathic manifestations. We report a case of 9-year-old boy with dysmorphic appearance and hypertrophic cardiomyopathy. Tandem MS spectrometry analysis was compatible with carnitine uptake defect (CUD). His sister had died due to sudden infant death at 19 months. His second 4-year-old sister's echocardiographic examination revealed hypertrophic cardiomyopathy, also suffering from easy fatigability. Her tandem MS spectrometry analyses resulted in CUD. We sequenced all the exons of the SLC22A5 gene encoding the high affinity carnitine transporter OCTN2 in the DNA. And one new mutation (c.1427T>G → p.Leu476Arg) was found in the boy and his sister in homozygous form, leading to the synthesis of an altered protein which causes CUD. The parent's molecular diagnosis supported the carrier status. In order to explore the genetic background of the patient's dysmorphic appearance, an array-CGH analysis was performed that revealed nine copy number variations only. Here we report a novel SLC22A5 mutation with the novel hallmark of its association with dysmorphologic feature.

Primary carnitine deficiency and cardiomyopathy

Carnitine is essential for the transfer of long-chain fatty acids from the cytosol into mitochondria for subsequent β-oxidation. A lack of carnitine results in impaired energy production from long-chain fatty acids, especially during periods of fasting or stress. Primary carnitine deficiency (PCD) is an autosomal recessive disorder of mitochondrial β-oxidation resulting from defective carnitine transport and is one of the rare treatable etiologies of metabolic cardiomyopathies. Patients affected with the disease may present with acute metabolic decompensation during infancy or with severe cardiomyopathy in childhood. Early recognition of the disease and treatment with L-carnitine may be life-saving. In this review article, the pathophysiology, clinical presentation, diagnosis, treatment and prognosis of PCD are discussed, with a focus on cardiac involvements.

Residual OCTN2 transporter activity, carnitine levels and symptoms correlate in patients with primary carnitine deficiency

BACKGROUND

The prevalence of primary carnitine deficiency (PCD) in the Faroe Islands is the highest reported in the world (1:300). Serious symptoms related to PCD, e.g. sudden death, have previously only been associated to the c.95A > G/c.95A > G genotype in the Faroe Islands. We report and characterize novel mutations associated with PCD in the Faroese population and report and compare free carnitine levels and OCTN2 transport activities measured in fibroblasts from PCD patients with different genotypes.

METHODS

Genetic analyses were used to identify novel mutations, and carnitine uptake analyses in cultured skin fibroblasts from selected patients were used to examine residual OCTN2 transporter activities of the various genotypes.

RESULTS

Four different mutations, including the unpublished c.131C > T (p.A44V), the novel splice mutation c.825-52G > A and a novel risk-haplotype (RH) were identified in the Faroese population. The two most prevalent genotypes were c.95A > G/RH (1:600) and c.95A > G/c.95A > G (1:1300). Patients homozygous for the c.95A > G mutation had both the significantly (p < 0.01) lowest mean free carnitine level at 2.03 (SD 0.66) μmol/L and lowest residual OCTN2 transporter activity (4% of normal). There was a significant positive correlation between free carnitine levels and residual OCTN2 transporter activities in PCD patients (R² = 0.430, p < 0.01).

CONCLUSION

There was a significant positive correlation between carnitine levels and OCTN2 transporter activities. The c.95A > G/c.95A > G genotype had the significantly lowest mean free carnitine level and residual OCTN2 transporter activity.

Systemic primary carnitine deficiency: an overview of clinical manifestations, diagnosis, and management

Systemic primary carnitine deficiency (CDSP) is an autosomal recessive disorder of carnitine transportation. The clinical manifestations of CDSP can vary widely with respect to age of onset, organ involvement, and severity of symptoms, but are typically characterized by episodes of hypoketotic hypoglycemia, hepatomegaly, elevated transaminases, and hyperammonemia in infants; skeletal myopathy, elevated creatine kinase (CK), and cardiomyopathy in childhood; or cardiomyopathy, arrhythmias, or fatigability in adulthood. The diagnosis can be suspected on newborn screening, but is established by demonstration of low plasma free carnitine concentration (<5 μM, normal 25-50 μM), reduced fibroblast carnitine transport (<10% of controls), and molecular testing of the SLC22A5 gene. The incidence of CDSP varies depending on ethnicity; however the frequency in the United States is estimated to be approximately 1 in 50,000 individuals based on newborn screening data. CDSP is caused by recessive mutations in the SLC22A5 gene. This gene encodes organic cation transporter type 2 (OCTN2) which transport carnitine across cell membranes. Over 100 mutations have been reported in this gene with the c.136C > T (p.P46S) mutation being the most frequent mutation identified. CDSP should be differentiated from secondary causes of carnitine deficiency such as various organic acidemias and fatty acid oxidation defects. CDSP is an autosomal recessive condition; therefore the recurrence risk in each pregnancy is 25%. Carrier screening for at-risk individuals and family members should be obtained by performing targeted mutation analysis of the SLC22A5 gene since plasma carnitine analysis is not a sufficient methodology for determining carrier status. Antenatal diagnosis for pregnancies at increased risk of CDSP is possible by molecular genetic testing of extracted DNA from chorionic villus sampling or amniocentesis if both mutations in SLC22A5 gene are known. Once the diagnosis of CDSP is established in an individual, an echocardiogram, electrocardiogram, CK concentration, liver transaminanses measurement, and pre-prandial blood sugar levels, should be performed for baseline assessment. Primary treatment involves supplementation of oral levocarnitine (L-carnitine) at a dose of 50-400 mg/kg/day divided into three doses. No formal surveillance guidelines for individuals with CDSP have been established to date, however the following screening recommendations are suggested: annual echocardiogram and electrocardiogram, frequent plasma carnitine levels, and CK and liver transaminases measurement can be considered during acute illness. Adult women with CDSP who are planning to or are pregnant should meet with a metabolic or genetic specialist ideally before conception to discuss management of carnitine levels during pregnancy since carnitine levels are typically lower during pregnancy. The prognosis for individuals with CDSP depends on the age, presentation, and severity of symptoms at the time of diagnosis; however the long-term prognosis is favorable as long as individuals remain on carnitine supplementation.

Homocysteine predicts increased NT-pro-BNP through impaired fatty acid oxidation

BACKGROUND

The deficiency in methyl donors, folate and vitamin B12, increases homocysteine and produces myocardium hypertrophy with impaired mitochondrial fatty acid oxidation and increased BNP, through hypomethylation of peroxisome-proliferator-activated-receptor gamma co-activator-1α, in rat. This may help to understand better the elusive link previously reported between hyperhomocysteinemia and BNP, in human. We investigated therefore the influence of methyl donors on heart mitochondrial fatty acid oxidation and brain natriuretic peptide, in two contrasted populations.

METHODS

Biomarkers of heart disease, of one carbon metabolism and of mitochondrial fatty acid oxidation were assessed in 1020 subjects, including patients undergoing coronarography and ambulatory elderly subjects from OASI cohort.

RESULTS

Folate deficit was more frequent in the coronarography population than in the elderly ambulatory volunteers and produced a higher concentration of homocysteine (19.3 ± 6.8 vs. 15.3 ± 5.6, P<0.001). Subjects with homocysteine in the upper quartile (≥ 18 μmol/L) had higher concentrations of NT-pro-BNP (or BNP in ambulatory subjects) and of short chain-, medium chain-, and long chain-acylcarnitines, compared to those in the lower quartile (≤ 12 μmol/L), in both populations (P<0.001). Homocysteine and NT-pro-BNP were positively correlated with short chain-, medium chain-, long chain-acylcarnitines and with acylcarnitine ratios indicative of decreased mitochondrial acyldehydrogenase activities (P<0.001). In multivariate analysis, homocysteine and long chain acylcarnitines were two interacting determinants of NT-pro-BNP, in addition to left ventricular ejection fraction, body mass index, creatinine and folate.

CONCLUSIONS

This study showed that homocysteine predicts increased NT-pro-BNP (or BNP) through a link with impaired mitochondrial fatty oxidation, in two contrasted populations.

Transient carnitine transport defect with cholestatic jaundice: report of one case in a premature baby

Carnitine (β-hydroxy-γ-trimethylaminobutyric acid) is involved in the transport of long-chain fatty acids into the mitochondrial matrix and the removal of potentially toxic acylcarnitine esters. Transient carnitine transport defect is a rare condition in newborns reported in 1/90,000 live births. In this paper, we describe a case of transient carnitine transport defect found in a premature baby who had prolonged cholestatic jaundice and poor weight gain, and who responded dramatically to oral carnitine supplementation.

[A cause of dilated cardiomyopathy in a child: primary carnitine deficiency]

AIM

The aim of this case report was to show the importance to research metabolic etiology, especially a carnitine deficiency in dilated cardiomyopathy of children.

CASE REPORT

A three years old Togolese child presented muscular hypotonia, dyspnea. Examination showed left galop murmur and systolic murmur 2/6. Chest X-ray showed cardiomegaly (CTI: 0.66), electrocardiogram, a sinusal rythm, left ventricle hypertrophy and T wave abnormalities. Echocardiogram showed a markedly dilated left ventricle with reduced systolic function (EF: 0.43; reference range 0.55-0.80) and moderate mitral regurgitation. The inflammatory signs where negatives. Magnetic resonance imaging don't show signs of ischemic or myocarditis. The levels of free and total plasmatic carnitine decreased: 3μmol/L (N: 18-48μmol/L) and 5μmol/l (N: 29-70μmol/L) respectively. Mutation analysis of the gene SLC22A5 confirms the diagnosis of primary systemic carnitine deficiency. Treatment with oral carnitine was started at 200mg/kg per day. Within three weeks of treatment, we observed the decrease of all symptoms and the left ventricular size and function normalized (EF: 0.62). He has now been on oral carnitine for live.

CONCLUSION

Primary carnitine deficiency is a cause of dilated cardiomyopathy in child. It must systematically be suspected when a child presents a primitive cardiomyopathy. The treatment with oral carnitine for live is simple, with excellent prognosis.

Primary carnitine deficiency and sudden death: in vivo evidence of myocardial lipid peroxidation and sulfonylation of sarcoendoplasmic reticulum calcium ATPase 2

OBJECTIVES

Primary carnitine deficiency is an autosomal recessive disorder caused by mutations in the SLC22A5 gene which results in impaired carnitine transport, cytosolic fatty acid accumulation and impaired beta oxidation. The disease is associated with cardiomyopathy and arrhythmias, but the mechanism is unknown. We hypothesized that carnitine deficiency results in increased myocardial oxidative stress.

METHODS

We evaluated a 22-year-old woman with primary carnitine deficiency and ventricular fibrillation, as well as her first-degree relatives.

RESULTS

Sequencing of SLC22A5 identified two deleterious mutations (A142S and R488H) and a novel mutation predicted to be a splice variant. Histology demonstrated increased myocardial lipid deposition and swollen mitochondria. Immunohistochemistry demonstrated accumulation of the reactive aldehyde 4-hydroxy-2-nonenal, indicative of increased lipid peroxidation, and sulfonylation of sarcoendoplasmic reticulum calcium ATPase 2 at cysteine 674.

CONCLUSIONS

These findings suggest that increased oxidant stress may contribute to myocardial dysfunction and arrhythmogenesis in this disorder.

Effect of L-carnitine on the synthesis of nitric oxide in RAW 264·7 murine macrophage cell line

L-Carnitine (β-hydroxy-γ-trimethyl aminobutyric acid) plays a critical role in inflammatory diseases by modulating inflammatory cell functions. Inducible nitric oxide synthase (iNOS), a proinflammatory enzyme responsible for the generation of nitric oxide (NO), has been implicated in the pathogenesis of inflammatory diseases. Mechanism of action of L-carnitine on inflammation via iNOS and nuclear factor κB (NF-κB) is unclear. In this study, we aimed to investigate the effect of L-carnitine on nitric oxide synthesis in lipopolysaccharide (LPS)-stimulated RAW 264·7 macrophage cells. For this purpose, cells were pretreated with various concentrations of L-carnitine and subsequently incubated with LPS (1 µg·ml(-1) ). NO levels, iNOS protein expression, and NF-κB activity were determined using colorimetric detection, Western blotting and transfection assays. Our results showed that treatment with L-carnitine suppressed nitric oxide production, iNOS protein expression and NF-κB activity. We demonstrated that inhibitory effect of L-carnitine on iNOS protein expression is at transcriptional level. This study may contribute to understanding the anti-inflammatory effect of L-carnitine.

Genotype-phenotype correlation in primary carnitine deficiency

Primary carnitine deficiency is caused by defective OCTN2 carnitine transporters encoded by the SLC22A5 gene. Lack of carnitine impairs fatty acid oxidation resulting in hypoketotic hypoglycemia, hepatic encephalopathy, skeletal and cardiac myopathy. Recently, asymptomatic mothers with primary carnitine deficiency were identified by low carnitine levels in their infant by newborn screening. Here, we evaluate mutations in the SLC22A5 gene and carnitine transport in fibroblasts from symptomatic patients and asymptomatic women. Carnitine transport was significantly reduced in fibroblasts obtained from all patients with primary carnitine deficiency, but was significantly higher in the asymptomatic women's than in the symptomatic patients' fibroblasts (P < 0.01). By contrast, ergothioneine transport (a selective substrate of the OCTN1 transporter, tested here as a control) was similar in cells from controls and patients with carnitine deficiency. DNA sequencing indicated an increased frequency of nonsense mutations in symptomatic patients (P < 0.001). Expression of the missense mutations in Chinese hamster ovary (CHO) cells indicated that many mutations retained residual carnitine transport activity, with no difference in the average activity of missense mutations identified in symptomatic versus asymptomatic patients. These results indicate that cells from asymptomatic women have on average higher levels of residual carnitine transport activity as compared to that of symptomatic patients due to the presence of at least one missense mutation.

Identification of mutations and evaluation of cardiomyopathy in Turkish patients with primary carnitine deficiency

Primary systemic carnitine deficiency (SCD) is an autosomal recessive disorder caused by defective cellular carnitine transport. Patients usually present with predominant metabolic or cardiac manifestations. SCD is caused by mutations in the organic cation/carnitine transporter OCTN2 (SLC22A5) gene. Mutation analysis of SLC22A5 gene was carried out in eight Turkish patients from six families. Six patients presented with signs and symptoms of heart failure, cardiomyopathy, and low plasma carnitine levels, five of them with concurrent anemia. A patient with dilated cardiomyopathy had also facial dysmorphia, microcephaly, and developmental delay. Tandem MS analyses in siblings of the patients revealed two more cases with low plasma carnitine levels. SCD diagnosis was confirmed in these two cases by mutation screening. These two cases were asymptomatic but echocardiography revealed left ventricular dilatation in one of them. Carnitine treatment was started before the systemic signs and symptoms developed in these patients. Mean value of serum carnitine levels of the patients was 2.63±1.92μmol/L at the time of diagnosis. After 1year of treatment, carnitine values increased to 16.62±5.11 (p<0.001) and all responded to carnitine supplementation clinically. Mutation screening of the OCTN2 gene study in the patients revealed two novel (p.G411V, p.G152R), and four previously identified mutations (p.R254X, p.R282X, p.R289X, p.T337Pfs12X). Early recognition and carnitine supplementation can be lifesaving in this inborn error of fatty acid oxidation.

Primary Carnitine Deficiency Presents Atypically with Long QT Syndrome: A Case Report

Primary carnitine deficiency (PCD) is an autosomal recessive disorder of fatty acid oxidation caused by mutations in the SLC22A5 gene encoding for the carnitine transporter OCTN2. Carnitine uptake deficiency results in renal carnitine wasting and low plasma levels. PCD usually presents early in life either with acute metabolic crisis or as progressive cardiomyopathy that responds to carnitine supplementation. PCD inclusion in the newborn screening (NBS) programs has led to the identification of asymptomatic adult patients ascertained because of a positive NBS in their offspring. We extensively reviewed the literature and found that 15 of 42 adult published cases (35.7%) were symptomatic. Cardiac arrhythmias were present in five patients (12%). Here, we report the ascertainment and long-term follow-up of the first case of PCD presenting with long QT syndrome. The patient presented in her early twenties with a syncopal episode caused by ventricular tachycardia, and a prolonged QT interval. Arrhythmias were poorly controlled by pharmacologic therapy and a defibrillator was installed. Syncopal episodes escalated during her first pregnancy. A positive NBS in the patient's child suggested a carnitine uptake deficiency, which was confirmed by reduced carnitine transporter activity and by molecular testing. After starting carnitine supplementation, no further syncopal episodes have occurred and the QT interval returned to normal. As precaution, a low-dose metoprolol therapy and the defibrillator are still in place. Although rare, PCD should be ruled out as a cause of cardiac arrhythmias since oral carnitine supplementation is readily available and efficient.

Lipid storage myopathy

Lipid storage myopathy (LSM) is pathologically characterized by prominent lipid accumulation in muscle fibers due to lipid dysmetabolism. Although extensive molecular studies have been performed, there are only four types of genetically diagnosable LSMs: primary carnitine deficiency (PCD), multiple acyl-coenzyme A dehydrogenase deficiency (MADD), neutral lipid storage disease with ichthyosis, and neutral lipid storage disease with myopathy. Making an accurate diagnosis, by specific laboratory tests including genetic analyses, is important for LSM as some of the patients are treatable: individuals with PCD show dramatic improvement with high-dose oral L-carnitine supplementation and increasing evidence indicates that MADD due to ETFDH mutations is riboflavin responsive.

Effects of combination of sibutramine and L-carnitine compared with sibutramine monotherapy on inflammatory parameters in diabetic patients

The aim of the study was to evaluate the effects of 12-month treatment with sibutramine plus L-carnitine compared with sibutramine alone on body weight, glycemic control, insulin resistance, and inflammatory state in type 2 diabetes mellitus patients. Two hundred fifty-four patients with uncontrolled type 2 diabetes mellitus (glycated hemoglobin [HbA(1c)] >8.0%) in therapy with different oral hypoglycemic agents or insulin were enrolled in this study and randomized to take sibutramine 10 mg plus L-carnitine 2 g or sibutramine 10 mg in monotherapy. We evaluated at baseline and after 3, 6, 9, and 12 months these parameters: body weight, body mass index, HbA(1c), fasting plasma glucose, postprandial plasma glucose, fasting plasma insulin, homeostasis model assessment of insulin resistance index, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, leptin, tumor necrosis factor-α, adiponectin, vaspin, and high-sensitivity C-reactive protein. Sibutramine plus L-carnitine gave a faster improvement of fasting plasma glucose, postprandial plasma glucose, lipid profile, leptin, tumor necrosis factor-α, and high-sensitivity C-reactive protein compared with sibutramine alone. Furthermore, there was a better improvement of body weight, HbA(1c), fasting plasma insulin, homeostasis model assessment of insulin resistance index, vaspin, and adiponectin with sibutramine plus L-carnitine compared with sibutramine alone. Sibutramine plus L-carnitine gave a better and faster improvement of all the analyzed parameters compared with sibutramine alone without giving any severe adverse effect.

Treatment strategies for acute metabolic disorders in neonates

Acute metabolic emergencies in neonates represent a challenge to the medical and nursing staff. If not treated optimally, these disorders are associated with poor outcome. Early diagnosis, supportive therapy and specific measures addressing the derranged metabolic process are the gold standards for favorable results. This review highlights treatment strategies for Inborn Errors of Metabolism (IEM) presenting in the neonatal period.

Comparison between orlistat plus l-carnitine and orlistat alone on inflammation parameters in obese diabetic patients

To evaluate the effects of 1-year treatment with orlistat plus L-carnitine compared to orlistat alone on body weight, glycemic and lipid control, and inflammatory parameters in obese type 2 diabetic patients. Two hundred and fifty-eight patients with uncontrolled type 2 diabetes mellitus (T2DM) [glycated hemoglobin (HbA(1c)) > 8.0%] in therapy with different oral hypoglycemic agents or insulin were enrolled in this study and randomized to take orlistat 120 mg three times a day plus L-carnitine 2 g one time a day or orlistat 120 mg three times a day. We evaluated the following parameters at baseline and after 3, 6, 9, and 12 months: body weight, body mass index (BMI), glycated hemoglobin (HbA(1c) ), fasting plasma glucose (FPG), postprandial plasma glucose (PPG), fasting plasma insulin (FPI), homeostasis model assessment insulin resistance index (HOMA-IR), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (Tg), adiponectin (ADN), leptin, tumor necrosis factor-α (TNF-α), vaspin, and high-sensitivity C-reactive protein (Hs-CRP). We observed a better decrease in body weight, glycemic profile, HOMA-IR, LDL-C, and ADN and a faster improvement in FPI, TC, Tg, leptin, TNF-α, Hs-CRP with orlistat plus L-carnitine compared to orlistat alone. We also recorded an improvement in vaspin with orlistat plus l-carnitine not reached with orlistat alone. Orlistat plus L-carnitine gave a better improvement in body weight, glycemic and lipid profile compared to orlistat alone; furthermore, a faster and better improvement in inflammatory parameters was observed with orlistat plus L-carnitine compared to orlistat alone.

End-stage cardiac disease as an initial presentation of systemic myopathies: case series and literature review

Life-threatening cardiomyopathy is associated with certain systemic myopathies and usually presents as an end-stage progression of the disease. However, cardiac symptoms can sometimes precede muscle weakness. The authors reviewed medical records from 2003 to 2008 on patients attending their neuromuscular clinic and identified patients who initially presented with an end-stage cardiomyopathy and were later diagnosed with a specific muscle disease through muscle biopsy. They report 5 cases of children who initially presented with cardiomyopathies without neuromuscular symptoms. The cardiac symptoms were so severe that 4 of them required cardiac transplantation and 1 died prior to transplantation. Review of muscle pathology confirmed the diagnoses of Becker muscular dystrophy, myofibrillar myopathy, mitochondrial myopathy with cytochrome oxidase deficiency, Danon disease, and glycogen storage disease. The authors conclude that cardiomyopathy can be the initial presentation of a wide spectrum of systemic myopathies. Careful evaluation of neuromuscular systems should be carried out in patients presenting with end-stage cardiomyopathies.

Timing and Duration of Drug Exposure Affects Outcomes of a Drug-Nutrient Interaction During Ontogeny

Significant drug-nutrient interactions are possible when drugs and nutrients share the same absorption and disposition mechanisms. During postnatal development, the outcomes of drug-nutrient interactions may change with postnatal age since these processes undergo ontogenesis through the postnatal period. Our study investigated the dependence of a significant drug-nutrient interaction (cefepime-carnitine) on the timing and duration of drug exposure relative to postnatal age. Rat pups were administered cefepime (5 mg/kg) twice daily subcutaneously according to different dosing schedules (postnatal day 1-4, 1-8, 8-11, 8-20, or 1-20). Cefepime significantly reduced serum and heart L-carnitine levels in postnatal day 1-4, 1-8 and 8-11 groups and caused severe degenerative changes in ventricular myocardium in these groups. Cefepime also altered the ontogeny of several key L-carnitine homeostasis pathways. The qualitative and quantitative changes in levels of hepatic γ-butyrobetaine hydroxylase mRNA and activity, hepatic trimethyllysine hydroxlase mRNA, intestinal organic cation/carnitine transporter (Octn) mRNA, and renal Octn2 mRNA depended on when during postnatal development the cefepime exposure occurred and duration of exposure. Despite lower levels of heart L-carnitine in earlier postnatal groups, levels of carnitine palmitoyltransferase mRNA and activity, heart Octn2 mRNA and ATP levels in all treatment groups remained unchanged with cefepime exposure. However, changes in other high energy phosphate substrates were noted and reductions in the phosphocreatine/ATP ratio were found in rat pups with normal serum L-carnitine levels. In summary, our data suggest a significant drug-nutrient transport interaction in developing neonates, the nature of which depends on the timing and duration of exposure relative to postnatal age.

Dilated cardiomyopathy in epidermolysis bullosa

Dilated cardiomyopathy (DC) is a rare but potentially fatal complication of epidermolysis bullosa. No clear cause for it has been identified, but iron overload, low carnitine, low selenium, concomitant viral illness, chronic anemia, and medications have been proposed as possible contributors to the development of DC in reported cases. Early detection allows for medical treatment that delays clinical progression and prolongs survival.

Dilated cardiomyopathy in epidermolysis bullosa: a retrospective, multicenter study

Dilated cardiomyopathy (DC) has been reported in severe epidermolysis bullosa (EB) subtypes. Poor nutritional status, low carnitine levels, selenium deficiency, chronic iron overload, drugs and viral etiology have been proposed as potential contributors. This was a retrospective, descriptive, multicenter study describing EB patients that developed DC, and determining potential pre-disposing risk factors. Fifteen patients were enrolled in the study; 11 of them were male subjects (73%). Eighty-seven per cent of the participants had dystrophic EB and 13% had junctional EB. Mean age at diagnosis of DC was 12.18 +/- 4.99 years. Chronic anemia was diagnosed in 13 of 15 patients (86.7%). Sixty per cent of patients had prior red blood cell transfusions. At diagnosis, selenium levels were low in 55% of the patients (n = 11) and total carnitine levels were low in 45% of the patients (n = 11). Systolic function was moderately impaired, with a mean shortening fraction of 19.38% (SD = 5.04, n = 8). After a mean follow-up period of 6.3 +/- 4.8 years, six patients were alive without being on any medications (40.0%), two were alive on medications (13.3%) and seven had died (46.7%). Limitations of the study was that it was a retrospective chart review with relatively small sample size. Retrospective chart review, relatively small sample size. This study substantiates the association between DC and EB. Currently, there is no single risk factor identified in EB patients that leads to DC. Further prospective studies are needed.

Cardiac conduction improvement in two heterozygotes for primary carnitine deficiency on L-carnitine supplementation

Expanded newborn screening (NBS) for free carnitine levels has led to the identification of a larger number of heterozygous infants of undiagnosed mothers affected with systemic primary carnitine deficiency (PCD), which in turn leads to the identification of other undiagnosed heterozygous family members. There is an increasing recognition that individuals heterozygous for mutations of genes involved in fatty acid oxidation (FAO) may become symptomatic under environmental stress (fasting, prolonged exercise and illness). Considering the importance of carnitine in FAO, its role in heart and bowel function and in lipid metabolism, what is still little known is the phenotypic variability, biochemical parameters and clinical course of PCD heterozygotes with consistently low-to-normal levels to low levels of carnitine over a lifetime. We report on three generations of a family--an asymptomatic PCD heterozygous infant identified through NBS that led to the diagnosis of her asymptomatic PCD-affected mother and the heterozygous status of the maternal grandparents who report some cardiac symptoms that overlap with PCD that improved with L-carnitine supplementation.

Orlistat and L-carnitine compared to orlistat alone on insulin resistance in obese diabetic patients

Our study wants to evaluate the effects of one year treatment with orlistat plus L-carnitine compared to orlistat alone on body weight, glycemic and lipid control, and insulin resistance state in type 2 diabetic patients. Two hundred and fifty-eight patients with uncontrolled type 2 diabetes mellitus (T2DM) [glycated hemoglobin (HbA(1c)) > 8.0%] in therapy with different oral hypoglycemic agents or insulin were enrolled in this study and randomised to take orlistat 120 mg three times a day plus L-carnitine 2 g one time a day or orlistat 120 mg three times a day. We evaluated at baseline, and after 3, 6, 9, and 12 months these parameters: body weight, body mass index (BMI), HbA(1c), fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), fasting plasma insulin (FPI), homeostasis model assessment insulin resistance index (HOMA-IR), total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), triglycerides (Tg), retinol binding protein-4 (RBP-4), resistin, visfatin, high sensitivity-C reactive protein (Hs-CRP). We observed a faster, and better decrease of body weight, HbA(1c), FPG, PPG, LDL-C, HOMA-IR with orlistat plus L-carnitine compared to orlistat. A faster improvement of TC, Tg, FPI, resistin, RBP-4, visfatin, and Hs-CRP was reached with orlistat plus L-carnitine compared to orlistat. We can safely conclude that the association of orlistat plus L-carnitine was better than orlistat in improving body weight, glycemic and lipid profile, insulin resistance, and inflammatory parameters and no significant adverse events were recorded.

Sibutramine and L-carnitine compared to sibutramine alone on insulin resistance in diabetic patients

OBJECTIVE

To evaluate the effects of one year of treatment with sibutramine plus L-carnitine compared to sibutramine on body weight, glycemic control, and insulin resistance state in type 2 diabetic patients.

METHODS

Two hundred and fifty-four patients with uncontrolled type 2 diabetes mellitus (T2DM) [glycated hemoglobin (HbA(1c)) >8.0%] in therapy with different oral hypoglycemic agents or insulin were enrolled in this study and randomised to take sibutramine 10 mg plus L-carnitine 2 g or sibutramine 10 mg in monotherapy. We evaluated at baseline, and after 3, 6, 9, and 12 months these parameters: body weight, body mass index (BMI), glycated hemoglobin (HbA(1c)), fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), fasting plasma insulin (FPI), homeostasis model assessment insulin resistance index (HOMA-IR), total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), triglycerides (Tg), retinol binding protein-4 (RBP-4), resistin, visfatin, high sensitivity-C reactive protein (Hs-CRP).

RESULTS

There was a decrease in body weight, BMI, HbA(1c), FPI, HOMA-IR, and RBP-4 in both groups, even when the values obtained with sibutramine plus L-carnitine were lower than the values obtained in sibutramine group. There was a faster decrease of FPG, PPG, TC, LDL-C, resistin and Hs-CRP with sibutramine plus L-carnitine even when no differences between the two groups were obtained. Furthermore, only sibutramine plus L-carnitine improved Tg, and visfatin.

CONCLUSION

Sibutramine plus L-carnitine gave a faster improvement of lipid profile, insulin resistance parameters, glycemic control, and body weight compared to sibutramine.