Long-term prognosis of fatty-acid oxidation disorders in adults: Optimism despite the limited effective therapies available.

INTRODUCTION: Fatty-acid oxidation disorders (FAODs) are recessive genetic diseases. MATERIALS AND METHODS: We report here clinical and paraclinical data from a retrospective study of 44 adults with muscular FAODs from six French reference centers for neuromuscular or metabolic diseases. RESULTS: The study cohort consisted of 44 adult patients: 14 with carnitine palmitoyl transferase 2 deficiency (32%), nine with multiple acyl-CoA deficiency (20%), 13 with very long-chain acyl-CoA dehydrogenase deficiency (30%), three with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (7%), and five with short-chain acyl-CoA dehydrogenase deficiency (11%). Disease onset occurred during childhood in the majority of patients (59%), with a mean age at onset of 15 years (range = 0.5-35) and a mean of 12.6 years (range = 0-58) from disease onset to diagnosis. The principal symptoms were acute muscle manifestations (rhabdomyolysis, exercise intolerance, myalgia), sometimes associated with permanent muscle weakness. Episodes of rhabdomyolysis were frequent (84%), with a mean creatinine kinase level of 68,958 U/L (range = 660-300,000). General metabolic complications were observed in 58% of patients, respiratory manifestations in 18% of cases, and cardiological manifestations in 9% of cases. Fasting acylcarnitine profile was used to orient genetic explorations in 65% of cases. After a mean follow-up of 10 years, 33% of patients were asymptomatic and 56% continued to display symptoms after exercise. The frequency of rhabdomyolysis decreased after diagnosis in 64% of cases. CONCLUSION: A standardized register would complete this cohort description of muscular forms of FAODs with exhaustive data, making it possible to assess the efficacy of therapeutic protocols in real-life conditions and during the long-term follow-up of patients.

The management and clinical outcomes of pregnancies in women with urea cycle disorders: A review of the literature and results of an international survey.

An increasing number of women with urea cycle disorders (UCDs) are reaching child-bearing age and becoming pregnant. Improved diagnostics and increased awareness of inherited metabolic diseases has also led to more previously undetected women being diagnosed with a UCD during or shortly after pregnancy. Pregnancy increases the risk of acute metabolic decompensation with hyperammonemia-which can occur in any trimester, and/or the postpartum period, and may lead to encephalopathy, psychosis, coma, and even death, if not diagnosed promptly and treated appropriately. There are also (theoretical) concerns that a maternal UCD, or its treatment, may cause potential risks for the unborn child. Currently evidence on management and outcome of pregnancies in UCDs is limited to case reports and there are no clear guidelines. In order to inform management and investigate outcomes of pregnancies in women with a UCD, we performed a retrospective review of published cases and analyzed data collected from an international online survey. We conclude that, although risk during the intra- and postpartum period exists, multidisciplinary management by an experienced team and a prospective plan usually result in successful pregnancy, labor, delivery, and postpartum period. No deaths were reported in mothers managed accordingly. With the exception of male neonates with Ornithine Transcarbamylase deficiency, the clinical outcome of children born to mothers with UCDs appears positive, although follow-up is limited. The outcome for women presenting with a first acute metabolic decompensation during pregnancy or postpartum is less favorable. Deaths were associated with diagnostic delay/late management of hyperammonemia in previously undiagnosed women.

Health status and comorbidities of adult patients with late-diagnosed phenylketonuria (PKU) born before the newborn screening in France - A nationwide study of health insurance claims data.

BACKGROUND: Phenylketonuria (PKU) is an inborn error of metabolism. When diagnosed late, it causes developmental delay or severe irreversible intellectual disability. This study aimed at evaluating the health status and healthcare consumption of late-diagnosed PKU patients in France. METHODS: This retrospective observational study used health insurance claims data from the French SNDS (Système National des Données de Santé) database, which contains data from over 66 million French inhabitants. Patients with PKU were identified between 2006 and 2018 by ICD-10 diagnosis codes E70.0 / E70.1 documented as a chronic condition (affection de longue durée - ALD) or in the inpatient setting. Patients with PKU were matched to controls by age, sex, and region. Patients with late-diagnosed PKU were defined as patients born before the nationwide implementation of newborn screening in France in 1972. Outcomes were analyzed for the year 2018. RESULTS: In total, 3549 patients with PKU were identified in the database on January 1st, 2018. Of those, 3469 patients could be matched to 17,170 controls without PKU. Of these, 2175 patients were at least 16 years old of whom 647 patients were categorized as late-diagnosed. The late-diagnosed PKU patients suffered significantly more often from hypertension (60.9% vs. 50.4%, p < 0.0001), hypercholesterolemia (41.7% vs. 26.9%, p < 0.0001), diabetes (24.4% vs. 14.1%, p < 0.0001), depression (20.6% vs. 13.8%, p < 0.0001), ischemic heart disease (16.1% vs. 6.6%, p < 0.0001), obesity (7.9% vs. 2.5%, inpatient diagnoses only, p < 0.0001), and chronic kidney disease (5.2% vs. 1.3%, inpatient diagnoses only, p < 0.0001) compared with their non-PKU controls. Consequently, significantly more patients with late-diagnosed PKU received medication to treat comorbidities associated with the nervous (82.6% vs 77.0%; p = 0.0021) and cardiovascular system (69.5% vs 58.0%; p < 0.0001). Overall, only 3.4% of patients with late-diagnosed PKU received dietary amino-acid supplements and 0.7% received sapropterin. CONCLUSION: The results indicate that PKU is associated with a significantly higher risk of comorbidities along with increased pharmaceutical prescriptions in patients with late-diagnosed PKU, compared with non-PKU controls. The increased risk of comorbidities was more pronounced than in patients with early-diagnosed PKU, as shown in previous research, but these patients are older than those with early-diagnosed PKU. Only few late-diagnosed patients were treated specifically for PKU. Patients with late-diagnosed PKU should be referred to specialized centers to prevent and manage comordities and introduce PKU-specific treatment when it is possible.

Health status and comorbidities of adult patients with phenylketonuria (PKU) in France with a focus on early-diagnosed patients - A nationwide study of health insurance claims data.

BACKGROUND: This study aimed at evaluating the health status and healthcare consumption of ≥16-year-old patients with phenylketonuria (PKU), with a focus on early-diagnosed patients. METHODS: This retrospective observational study used health insurance claims data from the French SNDS (Système National des Données de Santé) database. Patients with PKU were identified between 2006 and 2018 by ICD-10 diagnosis codes E70.0 (classic PKU) or E70.1 (other causes of hyperphenylalaninemia). They were matched to controls by age, sex, and region. Patients with early-diagnosed PKU were defined as patients born after implementation of nationwide newborn screening in France in 1972. Outcomes were analyzed for the year 2018. RESULTS: Overall, 3549 patients with PKU were identified on January 1st, 2018. Of those, 3469 patients could be matched to 17,170 controls without PKU. Of these patients, 2175 were at least 16 years old and suffered significantly more than controls from specific comorbidities of interest - osteoporosis (28.7% vs 19.8%, p < 0.0001), hypertension (20.9% vs 17.0%, p < 0.0001), hypercholesterolemia (12.8% vs 8.3%, p < 0.0001), diabetes (7.8% vs 4.7%, p < 0.0001), obesity (4.2% vs 1.3%, p < 0.0001), ischemic heart diseases (4.8% vs 2.0%, p < 0.0001), and depression (10.3% vs 8.2%, p = 0.0011). Prescriptions for many medications were also more frequent in patients with PKU than controls. Among ≥16-year-old patients, 1528 were categorized as early-diagnosed. Osteoporosis (0.3% vs 0.01%, p = 0.0035), chronic renal failure (0.6% vs 0.1%, p = 0.0020), hypertension (4.0% vs 2.7%, p = 0.0063), and obesity (2.5% vs 0.8%, p < 0.0001) were significantly more prevalent in early-diagnosed adult patients compared with matched controls. In total, 28.6% of ≥16-year-old patients with PKU and 40.4% of early-diagnosed patients with PKU received dietary amino-acid supplements. Sapropterin was prescribed to 5.0% and 7.0% patients, respectively. CONCLUSION: The results indicate that PKU is associated with a significantly higher comorbidity risk along with increased pharmaceutical prescriptions in adulthood. The comorbidity burden is less distinct in early-diagnosed patients but still present. Few patients are treated specifically for PKU in adulthood. Healthcare of patients with PKU should include prevention and management of comorbidities and especially target PKU-specific treatment adherence and consistent care in specialized medical centers in adulthood.

Comparison of biomarker for diagnosis of nitrous oxide abuse: challenge of cobalamin metabolic parameters, a retrospective study.

BACKGROUND: Recreational use of nitrous oxide (N2O) leads to neurological disorders including combined subacute degeneration of spinal cord, psychological disorders, and thrombosis. Serum or urine N2O assays could not be routinely performed. Hence, it is necessary to investigate other biological markers such as metabolic markers. We aimed here to challenge the three main biological markers used for the diagnosis of nitrous oxide abuse as total vitamin B12, homocysteine, and methylmalonic acid. METHODS: We retrospectively collected clinical and biological data from 52 patients with known, documented chronic N2O abuse and associated clinical signs (peripheral neuropathy disability score or thrombosis event). Sera and plasma total vitamin B12, methylmalonic acid (MMA), and homocysteine were performed to identify the most specific marker of chronic N2O intoxication and related clinical outcomes. RESULTS: Plasma homocysteine was almost consistently increased in case of N2O chronic consumption, whereas MMA increase and total vitamin B12 decrease are not systematically found. Our results showed that none of the markers are correlated with levels of N2O consumptions. However, homocysteine and MMA are correlated with clinical severity, but MMA seems to be a better marker of clinical severity. CONCLUSION: There is no specific marker of nitrous oxide abuse according to levels of consumption, total vitamin B12 decrease could not be used either as consumption or as severity marker. However, we showed that homocysteine is consistently increased and could be used as marker of recent N2O consumption. On the other hand, we showed that MMA could be used as a marker of clinical gravity.

Three-Country Snapshot of Ornithine Transcarbamylase Deficiency.

X-linked ornithine transcarbamylase deficiency (OTCD) is the most common urea cycle defect. The disease severity ranges from asymptomatic carrier state to severe neonatal presentation with hyperammonaemic encephalopathy. We audited the diagnosis and management of OTCD, using an online 12-question-survey that was sent to 75 metabolic centres in Turkey, France and the UK. Thirty-nine centres responded and 495 patients were reported in total. A total of 208 French patients were reported, including 71 (34%) males, 86 (41%) symptomatic and 51 (25%) asymptomatic females. Eighty-five Turkish patients included 32 (38%) males, 39 (46%) symptomatic and 14 (16%) asymptomatic females. Out of the 202 UK patients, 66 (33%) were male, 83 (41%) asymptomatic and 53 (26%) symptomatic females. A total of 19%, 12% and 7% of the patients presented with a neonatal-onset phenotype in France, Turkey and the UK, respectively. Vomiting, altered mental status and encephalopathy were the most common initial symptoms in all three countries. While 69% in France and 79% in Turkey were receiving protein restriction, 42% were on a protein-restricted diet in the UK. A total of 76%, 47% and 33% of patients were treated with ammonia scavengers in Turkey, France and the UK, respectively. The findings of our audit emphasize the differences and similarities in manifestations and management practices in three countries.

Cardiac Outcomes in Adults With Mitochondrial Diseases.

BACKGROUND: Patients with mitochondrial diseases are at risk of heart failure (HF) and arrhythmic major adverse cardiac events (MACE). OBJECTIVES: We developed prediction models to estimate the risk of HF and arrhythmic MACE in this population. METHODS: We determined the incidence and searched for predictors of HF and arrhythmic MACE using Cox regression in 600 adult patients from a multicenter registry with genetically confirmed mitochondrial diseases. RESULTS: Over a median follow-up time of 6.67 years, 29 patients (4.9%) reached the HF endpoint, including 19 hospitalizations for nonterminal HF, 2 cardiac transplantations, and 8 deaths from HF. Thirty others (5.1%) reached the arrhythmic MACE, including 21 with third-degree or type II second-degree atrioventricular blocks, 4 with sinus node dysfunction, and 5 sudden cardiac deaths. Predictors of HF were the m.3243A>G variant (HR: 4.3; 95% CI: 1.8-10.1), conduction defects (HR: 3.0; 95% CI: 1.3-6.9), left ventricular (LV) hypertrophy (HR: 2.6; 95% CI: 1.1-5.8), LV ejection fraction <50% (HR: 10.2; 95% CI: 4.6-22.3), and premature ventricular beats (HR: 4.1; 95% CI: 1.7-9.9). Independent predictors for arrhythmia were single, large-scale mtDNA deletions (HR: 4.3; 95% CI: 1.7-10.4), conduction defects (HR: 6.8; 95% CI: 3.0-15.4), and LV ejection fraction <50% (HR: 2.7; 95% CI: 1.1-7.1). C-indexes of the Cox regression models were 0.91 (95% CI: 0.88-0.95) and 0.80 (95% CI: 0.70-0.90) for the HF and arrhythmic MACE, respectively. CONCLUSIONS: We developed the first prediction models for HF and arrhythmic MACE in patients with mitochondrial diseases using genetic variant type and simple cardiac assessments.

A case of pink urine associated with abdominal pain crisis / Un cas d'urines roses associées à des crises de douleurs abdominales

An adolescent girl consults a physician for abdominal pain attacks occurring regularly for 2 years. After eliminating gastroenterologic or gynecologic causes, an acute hepatic porphyria is suspected. The pink color of her urine seems consistent with the suspicion of porphyria; however, the urinary profile of porphyrins and its precursors is normal.

Une adolescente consulte son médecin pour des crises de douleurs abdominales survenant de manière régulière depuis environ 2 ans. Après avoir éliminé une étiologie gastro-intestinale ou gynécologique, une porphyrie aiguë hépatique est suspectée. Un bilan urinaire est alors réalisé. La coloration rose des urines est en faveur de cette hypothèse, cependant le profil urinaire des porphyrines et de ses précurseurs est normal, excluant une crise aiguë de porphyrie.

A novel HADHA variant associated with an atypical moderate and late-onset LCHAD deficiency.

Background: Long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare inherited disease caused by pathogenic variants of HADHA gene. Along with signs common to fatty acid oxidation defects (FAOD), specific retina and heart alterations are observed. Because long-chain fatty acid oxidation is selectively affected, supplementations with short/medium-chain fats represent energetic sources bypassing the enzymatic blockade. Here, we report on an atypical presentation of the disease. Methods: Clinical features were described with medical explorations including ophthalmic and cardiac examination. Biological underlying defects were investigated by measurements of biochemical metabolites and by fluxomic studies of mitochondrial ß-oxidation. Whole exome sequencing and molecular validation of variants confirmed the diagnosis. Results: The patient has developed at nine years an unlabeled maculopathy, and at 28 years, an acute cardiac decompensation without any premise. Blood individual acylcarnitine analysis showed a rise in hydroxylated long-chain fatty acids and fluxomic studies validated enzyme blockade consistent with LCHADD. Genetic analysis revealed the common p.(Glu510Gln) variant in HADHA, in trans with a novel variant c.1108G > A, p.(Gly370Arg) located in the NAD binding domain. Patient pathology was responsive to triheptanoin supplementation. Conclusion: This atypical LCHADD form report should encourage the early assessment of biochemical and genetic testing as a specific management is recommended (combination with fast avoidance, low fat-high carbohydrate diet, medium-even-chain triglycerides or triheptanoin supplementation).

Sphingosine-1-Phosphate Levels Are Higher in Male Patients with Non-Classic Fabry Disease.

Fabry disease is an X-linked lysosomal disease in which defects in the alpha-galactosidase A enzyme activity lead to the ubiquitous accumulation of glycosphingolipids. Whereas the classic disease is characterized by neuropathic pain, progressive renal failure, white matter lesions, cerebral stroke, and hypertrophic cardiomyopathy (HCM), the non-classic phenotype, also known as cardiac variant, is almost exclusively characterized by HCM. Circulating sphingosine-1-phosphate (S1P) has controversially been associated with the Fabry cardiomyopathy. We measured serum S1P levels in 41 patients of the FFABRY cohort. S1P levels were higher in patients with a non-classic phenotype compared to those with a classic phenotype (200.3 [189.6−227.9] vs. 169.4 ng/mL [121.1−203.3], p = 0.02). In a multivariate logistic regression model, elevated S1P concentration remained statistically associated with the non-classic phenotype (OR = 1.03; p < 0.02), and elevated lysoGb3 concentration with the classic phenotype (OR = 0.95; p < 0.03). S1P levels were correlated with interventricular septum thickness (r = 0.46; p = 0.02). In a logistic regression model including S1P serum levels, phenotype, and age, age remained the only variable significantly associated with the risk of HCM (OR = 1.25; p = 0.001). S1P alone was not associated with cardiac hypertrophy but with the cardiac variant. The significantly higher S1P levels in patients with the cardiac variant compared to those with classic Fabry suggest the involvement of distinct pathophysiological pathways in the two phenotypes. S1P dosage could allow the personalization of patient management.

Acid Sphingomyelinase Deficiency: Sharing Experience of Disease Monitoring and Severity in France.

Acid sphingomyelinase deficiency (ASMD) is a rare inherited lipid storage disorder caused by a deficiency in lysosomal enzyme acid sphingomyelinase which results in the accumulation of sphingomyelin, predominantly within cells of the reticuloendothelial system located in numerous organs, such as the liver, spleen, lungs, and central nervous system. Although all patients with ASMD share the same basic metabolic defect, a wide spectrum of clinical presentations and outcomes are observed, contributing to treatment challenges. While infantile neurovisceral ASMD (also known as Niemann-Pick disease type A) is rapidly progressive and fatal in early childhood, and the more slowly progressive chronic neurovisceral (type A/B) and chronic visceral (type B) forms have varying clinical phenotypes and life expectancy. The prognosis of visceral ASMD is mainly determined by the association of hepatosplenomegaly with secondary thrombocytopenia and lung disease. Early diagnosis and appropriate management are essential to reduce the risk of complications and mortality. The accessibility of the new enzyme replacement therapy olipudase alfa, a recombinant human ASM, has been expedited for clinical use based on positive clinical data in children and adult patients, such as improved respiratory status and reduced spleen volume. The aim of this article is to share the authors experience on monitoring ASMD patients and stratifying the severity of the disease to aid in care decisions.

Nitrous oxide abuse in the emergency practice, and Review of toxicity mechanisms and potential markers.

Nitrous oxide (N2O) toxicity is a concern common to several medical fields. Here, retrospective study of four N2O abuses with neurological signs in the emergency practice provides a preliminary basis for a metabolic Discussion/Review. This latter highlights N2O abuse as pathology of DNA/RNA/protein methylations, for instance consistent with impairments of protein arginine methyltransferases involved in myelinogenesis and myelopathy in patients. Basically, pathogenesis starts with oxidation by N2O of coordinated cobalamine cobalt ions at enzyme sites with impairments of vitamin-B12-dependent pathways. Methionine synthase (methylcobalamine) and methymalonyl-CoA mutase (adenosylcobalamine) are inactivated and cofactor-depleted, respectively. The number of impacted pathways (folate cycle, methylation cycle, S-adenosylmethionine-dependent methyltransferases, transulfuration pathway, Krebs cycle fueling by methylmalonyl-CoA, glutathione synthesis) explains the variety of potential research/laboratory markers, and may provide new clues and future angles to explore N2O toxicity. Overall, homocysteine measurements obviously help diagnosis of N2O abuses. Additional markers may include vitamin-B12, methionine, methylmalonate, dimethylglycine, sarcosine, S-adenosylmethionine to S-adenosylhomocysteine ratio, various S-adenosylamino acids, S-adenosylmethionine-dependent cellular methylations, and additional analytes (propionylcarnitine, propionylglycine, cystathionine and derived metabolites, methylated amino acids [eg arginine], betaine).

Givosiran in acute intermittent porphyria: A personalized medicine approach.

BACKGROUND: In patients with acute intermittent porphyria (AIP), induction of delta aminolevulinic acid synthase 1 (ALAS1) leads to haem precursor accumulation that may cause recurring acute attacks. In a recent phase III trial, givosiran significantly reduced the attack rate in severe AIP patients. Frequent adverse events were injection-site reaction, fatigue, nausea, chronic kidney disease and increased alanine aminotransferase. OBJECTIVES: To describe the efficacy and safety of givosiran based on a personalized medical approach. METHODS: We conducted a retrospective patient file study in 25 severe AIP patients treated with givosiran in France. We collected data on clinical and biochemical efficacy along with reports of adverse events. RESULTS: Givosiran drastically reduced the attack rate in our cohort, as 96% were attack-free at the time of the study. The sustained efficacy of givosiran in most patients allowed us to personalize dosing frequency. In 42%, givosiran was only given when haem precursor levels were increasing. Our data suggest that givosiran is most effective when given early in the disease course. We confirmed a high prevalence of adverse events. One patient discontinued treatment due to acute pancreatitis. All patients had hyperhomocysteinemia, and all patients with initial homocysteine levels available showed an increase under treatment. In this context, one patient was diagnosed with pulmonary embolism. CONCLUSION: The sustained effect of givosiran allowed a decrease in dosing frequency without compromising treatment efficacy. The high prevalence of adverse events emphasizes the importance of restricting the treatment to severe AIP and administering the minimum effective dose for each patient.

Plasma Methionine and Clinical Severity in Nitrous Oxide Consumption.

In the last few years, there has been an increase in the recreational use of nitrous oxide (N2O), which can lead to neurological symptoms such as sensory or motor disorders. The literature links these symptoms to a functional inactivation of vitamin B12 by oxidation of its cobalt ion, which prevents the vitamin B12 from acting as a cofactor for methionine synthase. Thus, demyelination related to methionine deficiency could be responsible for the neurological disorders associated with N2O consumption, including the combined sclerosis of the spinal cord. We aimed to study the correlation between the plasma methionine levels and clinical severity observed in N2O users. We retrospectively collected clinical and biological data from 93 patients who chronically consumed N2O. The patients were divided into four groups based of the severity of their clinical symptoms (based on their Peripheral Neuropathy Disability (PND) score). The plasma amino acids measurement, including methionine, were performed systematically by liquid chromatography coupled with mass spectrometry. Plasma methionine is significantly correlated with the clinical severity (Spearman coefficient: −0.42; p-value < 10−5), however, the average methionine level in the four groups is within the physiological values (N: 16−23 µmol/L). There is a significant inverse correlation between plasma methionine and homocysteine (Spearman coefficient: −0.57; p-value < 10−9), which confirms the action of nitrous oxide on the methionine synthase. A decrease in plasma methionine cannot be imputed as the only mechanism involved in the pathophysiology of the neurological disorders in nitrous oxide consumption. In addition, there are few therapeutic indications for the use of methionine. Thus, we should be careful concerning the potential use of methionine in nitrous oxide consumption. As a consequence, other pathophysiological mechanisms probably need to be identified in order to find potential therapeutic targets.

Variation of the serum N-glycosylation during the pregnancy of a MPI-CDG patient.

For the first time the glycosylation of a patient with a MPI-CDG during pregnancy is monitored. MPI-CDG, is characterised by a deficiency in mannose-6-phosphate isomerase (MPI) leading to a reduced pool of glycosylation precursors, impairing the biosynthesis of N-glycans leading to N-glycosylation defects. The abnormal N-glycosylation profile with an elevation of asialotransferrin and disialotransferrin, typical of CDG type I, is assessable by transferrin isoelectrofocusing. Oral D-mannose supplementation for MPI-CDG patients has been widely used and improves clinical manifestations. The glycosylation of a MPI-CDG patient during pregnancy without mannose supplementation was studied using carbohydrate deficient transferrin (CDT) assay, transferrin isoelectrofocusing (IEF) and mass spectrometry of total serum N-glycans. A general improvement of the glycosylation profile of the patient due to a better transfer of the glycan precursors as well as an increase of the triantennary glycans (and sialylation) was observed. In conclusion, in the absence of mannose supplementation, the previously observed glycosylation abnormality of the MPI-CDG patient was corrected. The molecular mechanism underlying this N-glycosylation rescue during MPI-CDG pregnancy further needs to be investigated.

Metreleptin treatment of non-HIV lipodystrophy syndromes.

Lipodystrophy syndromes (LS) constitute a group of rare diseases of the adipose tissue, characterized by a complete or selective deficiency of the fat mass. These disorders are associated with important insulin resistance, cardiovascular and metabolic comorbidities that impact patient's survival and quality of life. Management is challenging and includes diet, physical activity, and specific pharmacological treatment of LS-associated comorbidities. Because of a common pathophysiology involving decreased concentration of the adipokine leptin, efforts have been made to develop therapeutic strategies with leptin replacement therapy. Metreleptin, a recombinant human leptin analogue, has been proposed in hypoleptinemic patients since the beginning of 2000's. The treatment leads to an improvement in metabolic parameters, more important in generalized than in partial LS forms. In this review, the current knowledge about the development of the drug, its outcomes in the treatment of lipodystrophic patients as well as the peculiarities of its use will be presented.

Citrin deficiency: Does the reactivation of liver aralar-1 come into play and promote HCC development?

Hepatocellular carcinoma (HCC) is a longstanding issue in clinical practice and metabolic research. New clues in better understanding the pathogenesis of HCC might relate to the metabolic context in patients with citrin (aspartate-glutamate carrier 1) deficiency (CD). Because citrin-deficient liver (CDL) is subject to HCC, it represents a unique metabolic model to highlight the mechanisms of HCC promotion, offering different angles of study than the classical metabolic syndrome/obesity/non-alcoholic fatty liver disease (NAFLD)/HCC study axis. In turn, the metabolic features of HCC could shed light on the pathogenesis of CDL. Among these, HCC-induced re-activation of aralar-1 (aspartate-glutamate carrier 2), physiologically not expressed in the adult liver, might take place in CDL, so gene redundancy for mitochondrial aspartate-glutamate carriers would be exploited by the CDL. This proposed (aralar-1 re-activation) and known (citrate/malate cycle) adaptive mechanisms may substitute for the impaired function in CD and are consistent with the clinical remission stage of CD and CD improvement by medium-chain triglycerides (MCT). However, these metabolic adaptive benefits could also promote HCC development. In CD, as a result of PPARα down-regulation, liver mitochondrial fatty acid-derived acetyl-CoA would, like glucose-derived acetyl-CoA, be used for lipid anabolism and fuel nuclear acetylation events which might trigger aralar-1 re-activation as seen in non-CD HCC. A brief account of these metabolic events which might lead to aralar-1 re-activation in CDL is here given. Consistency of this account for CDL events further relies on the protective roles of PPARα and inhibition of mitochondrial and plasma membrane citrate transporters in non-CD HCC.