Free Carnitine Levels Research Articles

Dramatic Decrease of Carnitine Esters after Interruption of Exogenous Carnitine Supply in Hemodialysis Patients

L-carnitine supplementation is extensively used in patients on maintenance hemodialysis (HD) to improve dialysis-related clinical symptoms. In a series of studies, we investigated the dynamics of carnitine pool in carnitine-supplemented HD patients; here we report dramatic decrease with special changes of the ester profile due to interruption of the exogenous intake after the last HD session. Serum samples were collected from 18 L-carnitine-repleted end-stage renal disease (ESRD) patients before the L-carnitine supplementation, after completion of a carnitine supplementation period treatment (12 weeks, 1 g/IV/HD), right before the HD session, and 44 h after the dialysis. Levels of free carnitine (FC) and the individual esters were determined using electrospray MS/MS technique. Normally, L-carnitine supplementation causes significant elevation of all carnitine compounds to supraphysiological levels, which reaches a standard steady-state-like profile. In this study we found a dramatic decrease in the level of FC, and in short- and medium-chain acylcarnitines (ACs) 44 h after the last dialysis. At the end of this interdialytic period, FC levels increased to only 65% of the predialysis level, whereas the amounts of C2 and C3 esters recovered to only 50%. The level of C6 was 65% of the predialysis level, whereas the amount of C8 chain length ACs returned to 72% of the predialysis level. No significant change was seen in AC concentrations above C10 chain length. Omission of one single dosage of supplemental carnitine in long-term administration schemes results in dramatic decrease and reprofiling of carnitine esters even after the usual 44 h of interdialytic period.

The metabolic effects of two different lipid emulsions used in parenterally fed premature infants — A randomized comparative study

ObjectiveTo compare the effects of two different lipid emulsions, based on soybean oil and olive oil respectively on plasma lipid concentrations and acylcarnitine profile of very low birth weight infants. DesignRandomized comparative study. Patients and methodsForty very low birth weight infants, ≤32weeks of gestational age and receiving at least 40% of the calorie taken by parenteral nutrition from lipid solution at 14th day of life were evaluated. Group I (n=20) received soybean oil based lipid emulsion (Intralipid®) and Group II (n=20) received olive oil based lipid emulsion (Clinoleic®). Main outcome measuresPlasma lipid concentrations and acylcarnitine profile were assessed. ResultsTriglyceride, cholesterol, high and low density lipoprotein levels, liver function tests were similar between two groups whereas very low density lipoprotein level was statistically lower in Group I (p<0.05). Free carnitine levels were 15.73±10.67 in Group I and 34.25±22.18μM in Group II (p=0.012) and hexanoyl carnitine levels 2.18±2.10 in Group I and 0.38±0.12μM in Group II, respectively (p=0.005). Plasma medium chain acylcarnitine levels were significantly higher in Group I. ConclusionsLow levels of very low density lipoprotein in Group I may be a way of hemostasis to keep the serum triglyceride within normal levels. Lower free carnitine levels in soybean oil-based group is the result of carnitine need during the mitochondrial transport of long chain fatty acids. In Group I, due to the inefficient transport of medium chain fatty acids into the mitochondria, medium chain acylcarnitines accumulate in plasma. This may be the reason of lower carnitine levels in Group I. We suggest that higher levels of hexanoyl carnitine, reflecting defective mitochondrial transport of hexanoyl which leads immunsupression, may be the cause of higher sepsis risk in Group I.

The Effects of Carnitine Supplementation in Hemodialysis Patients

Objectives: Patients receiving hemodialysis have been shown to be carnitine deficient due to many causes. Tissues, especially the skeletal muscle and myocardium, require carnitine for the production of energy. This study was performed to find out the effects of L-carnitine supplementation on muscular symptoms and cardiac functions in dialysis patients. Methods: Among 72 hemodialysis patients, 40 patients who showed decreased free carnitine levels were selected to receive L-carnitine intravenously after each hemodialysis session for 6 months. Before and after supplementation, echocardiography, various neurologic examinations and questionnaires were obtained. Results: After carnitine treatment for 6 months (1∼1.5 g per every hemodialysis session), the blood level of carnitine was increased more than 10 times (19.04±7.12 μmol/L vs. 267.24±69.94 μmol/L, P＜0.001). The left ventricular ejection fraction was improved in the patients who have less than 60% of ejection fraction (56.45±2.53% vs. 60.44±6.29%, P=0.03) after carnitine treatment. The neurological symptom score and isometric muscle power (pinch power) were improved, but the total neuropathy score, activities of daily living scale and grip power were not changed after carnitine supplementation on dialysis patients. Conclusion: Regular L-carnitine supplementation on hemodialysis patients can improve their left ventricular ejection fraction and some parts of functionality. (Ewha Med J 2012;35(2):89-94)

Une cause de cardiomyopathie dilatée chez l’enfant : le déficit primaire en carnitine

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

L-Carnitine Improves the Asthma Control in Children with Moderate Persistent Asthma

The objective. was to investigate L-Carnitine level and the effects of its supplementation in children with moderate persistent Asthma. Methods. Free and total serum carnitine levels were measured in 50 children having moderate persistent asthma and 50 healthy control children. The patients group was randomly divided into two subgroups. Subgroup A was supplemented with L-carnitine for 6 months while subgroup B was used as a placebo controls. Both subgroups were assessed by pulmonary function tests (PFT) and childhood-asthma control test (C-ACT) before and 6 months after carnitine supplementation. Results. Total and free carnitine levels were significantly lower in patient group than in control group. PFT and C-ACT showed significant improvements in asthmatic children supplemented with L-carnitine than in those who were not supplemented. Conclusion. L-carnitine levels were initially lower in moderate persistent asthmatic children as compared to healthy control children. Asthmatic children who received L-carnitine supplementation showed statistically significant improvement of C-ACT and PFT.

Abstract 8573: L-carnitine Prevents Heart Failure with Preserved Ejection Fraction in Associated with Attenuation of Cardiac Fibrosis

Backgrounds: Prognosis of heart failure with preserved ejection fraction (HFpEF) has not been improved because of unknown pathophysiology and unestablished therapeutic strategy. Cardiac fibrosis is known to play a crucial role in the development of HFpEF. Methods and Results: The comprehensive and quantitative analysis of metabolites with capillary electrophoresis time-of-flight mass spectrometry was conducted to find a substance which may be related to the development of HFpEF, and revealed decreased plasma free-carnitine levels in Dahl salt-sensitive rats (DSR) fed high-salt diet, a model of hypertensive HFpEF. We confirmed this result with enzymatic cycling method by showing decreased plasma and left ventricular (LV) free-carnitine levels with increased urinary free-carnitine excretion in HFpEF rats compared to control DSR fed normal chow. We also found that blood free-carnitine levels were decreased in HFpEF patients compared to age-matched normal volunteers. Expression of organic cation/carnitine transporter 2, which transports free-carnitine into cells, was decreased in the LV and kidney of HFpEF rats. L-carnitine administration to HFpEF rats increased plasma and LV levels of free-carnitine, and prevented HFpEF with decreased myocardial stiffness constant and decreased area of LV fibrosis. In cultured cardiac fibroblasts, L-carnitine attenuated the angiotensin II-induced increase in 3 H-proline incorporation. L-carnitine increased prostacyclin production and expression of fatty acid desaturase 1/2, rate-limiting enzymes in forming arachidonic acid, in the LV of DSR and cultured cardiac fibroblasts. LV arachidonic acid levels were increased in HFpEF rats by L-carnitine administration. Conclusions: L-carnitine may be effective in the prevention of HFpEF through enhanced production of prostacyclin and prevention of LV fibrosis and stiffening. L-carnitine supplementation may become a therapeutic option for HFpEF.

Recognizing and Treating Valproic Acid Toxicity: A Case Report

Valproic Acid (VPA) toxicity has been steadily increasing in frequency since the FDA approved the drug for acute mania in 1995. According to the 2005 Annual Report of the American Association of Poison Control Center's Toxic Exposure Surveillance System (TESS), 8705 acute exposures to valproic acid occurred with major adverse outcomes reported in 404 patients of this cohort. Recognizing VPA toxicity is the first step in properly managing the patient. Key signs and symptoms of VPA toxicity include: CNS depression, lethargy and potential encephalopathy, respiratory depression, nausea/vomiting, and myoclonus. Lab abnormalities often include, in addition to elevated serum VPA levels, hypernatremia, elevated anion gap metabolic acidosis, hyperosmolality, hypocalcemia, and hyperammonemia with a transaminitis. A non-contrast head CT may demonstrate cerebral edema, the peak occurrence of which is between 12 hours and 4 days after ingestion. Activated charcoal can be given early if the timing of overdose is known. Serial head CT scans should be ordered to monitor the possible delayed side effect of cerebral edema. Other areas of treatment deal with correcting the ill effects of the metabolic abnormalities (e.g. replace calcium if hypocalcemia). Specifically, lactulose is used to decrease serum ammonia levels and reduce the risk of encephalopathy. Another mainstay of treatment, L-carnitine, increases levels of free carnitine to participate in mitochondrial fatty acid synthesis. In extreme cases, hemodialysis may be required to reduce the levels of VPA and the associated metabolites. Of note our patient presented with virtually all the lab abnormalities and symptoms typical of VPA toxicity. He improved with hemodialysis and was discharged to a mental health facility in stable condition. Though VPA toxicity occurs rarely, it has a consistent presentation, symptomotology and defined treatment regimen. Awareness of a typical patient’s presentation would assist in early diagnosis and a successful treatment. J Med Cases. 2011;2(5):185-187 doi: https://doi.org/10.4021/jmc234w

Altered carnitine metabolism in dialysis patients with reduced physical function may be due to dysfunctional fatty acid oxidation

It has been reported that hemodialysis patients have elevated plasma acylcarnitine concentrations, which correlates to reduced red blood cell integrity. It has also been reported that the supplementation of L-carnitine for these patients improves anemia, glucose metabolism and muscle function, but the mechanism of these relationships remains unknown. We hypothesized that the cause of increased plasma acylcarnitines is incomplete fatty acid oxidation and the underlying disturbance of metabolism reduces muscle function, resulting in decreased ability to function and quality of life, and glucose availability, resulting in decreased red blood cell integrity and worsened anemia. This analysis was conducted on baseline data from a clinical trial of carnitine supplementation in hemodialysis patients with reduced physical function and free carnitine levels. Partial correlations controlling for age, gender, hemoglobin and subjective global assessment score for each acylcarnitine species and outcome were computed using SPSS version 17.0 and a significance level of P < 0.05. To measure the impact of acylcarnitine acyl chain length on these relationships, the correlation coefficients were categorized by chain length and linear regressions were computed for each outcome measure. Linear regression analysis (n = 58) revealed significant negative relationships between chain length and Short Form-36 physical composite score, sit-to-stand count and 6-min walk distance (r(2) = 0.635, 0.332 and 0.347, respectively) and a significant positive relationship with erythropoietin dose (r(2) = 0.181). Our data revealed that longer acyl chain length significantly predicts poorer physical function and worsened anemia, and this data supports our proposed mechanism, which may lead to increased understanding of altered carnitine metabolism in hemodialysis patients.

L-carnitine ameliorates cancer cachexia in mice by regulating the expression and activity of carnitine palmityl transferase

Cancer cachexia is characterized by progressive weight loss with the depletion of adipose tissue and skeletal muscle. Impaired fatty acid oxidation mainly resulting from the decrease of carnitine palmitoyltransferase I and II activities in the liver is an important factor that contributes to cancer cachexia . Although recent studies suggest a potential application of L-carnitine in treatment of cancer cachexia, the underlying mechanisms are unknown. In the present study, we aim to assess the effects of L-carnitine on the activity and expression of CPT I and II in the liver of cachectic cancer mice. Our results show that the inoculation of colon-26 adenocarcinoma cells into mice led to cancer cachexia characterized by notable decreases in food intake, gastrocnemius muscle and epididymus fat weight. In addition, the mRNA level and activity of liver carnitine palmitoyltransferase (CPT) I and II, and serum levels of free carnitine and acetylcarnitine were markedly decreased in cachectic mice, accompanied by marked increases in serum levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). A continuous oral treatment with L-carnitine at 18 mg/kg per day increased dietary uptake, gastrocnemius muscle weight and epididymus fat weight, increased blood glucose and serum albumin levels, and decreased total cholesterol level in cancer cachectic mice, but did not affect tumor growth. These effects of L-carnitine on cancer cachexia mice were accompanied by the upregulation of mRNA level of CPT I and II and increased enzyme activity of CPT I in the liver, as well as the downregulation of serum TNF-α and IL-6 levels. Moreover, free carnitine levels were negatively correlated with serum TNF-α or IL-6 level. These results indicate that L-carnitine ameliorates cancer cachexia by regulating serum TNF-α and IL-6 levels and modulating the expression and activity of CPT in the liver.

Differential effects of short- and long-term high-fat diet feeding on hepatic fatty acid metabolism in rats

Imbalance in the supply and utilization of fatty acids (FA) is thought to contribute to intrahepatic lipid (IHL) accumulation in obesity. The aim of this study was to determine the time course of changes in the liver capacity to oxidize and store FA in response to high-fat diet (HFD). Adult male Wistar rats were fed either normal chow or HFD for 2.5weeks (short-term) and 25weeks (long-term). Short-term HFD feeding led to a 10% higher palmitoyl-l-carnitine-driven ADP-stimulated (state 3) oxygen consumption rate in isolated liver mitochondria indicating up-regulation of β-oxidation. This adaptation was insufficient to cope with the dietary FA overload, as indicated by accumulation of long-chain acylcarnitines, depletion of free carnitine and increase in FA content in the liver, reflecting IHL accumulation. The latter was confirmed by in vivo1H magnetic resonance spectroscopy and Oil Red O staining. Long-term HFD feeding caused further up-regulation of mitochondrial β-oxidation (24% higher oxygen consumption rate in state 3 with palmitoyl-l-carnitine as substrate) and stimulation of mitochondrial biogenesis as indicated by 62% higher mitochondrial DNA copy number compared to controls. These adaptations were paralleled by a partial restoration of free carnitine levels and a decrease in long-chain acylcarnitine content. Nevertheless, there was a further increase in IHL content, accompanied by accumulation of lipid peroxidation and protein oxidation products. In conclusion, partially effective adaption of hepatic FA metabolism to long-term HFD feeding came at a price of increased oxidative stress, caused by a combination of higher FA oxidation capacity and oversupply of FA.

Plasma carnitine is associated with fatigue in chronic hepatitis C but not in the irritable bowel syndrome

Fatigue is an important determinant of altered quality of life in patients affected by chronic hepatitis C or the irritable bowel syndrome (IBS). In this study, we aimed at determining the contributory role of plasma levels of leptin and carnitine on fatigue in chronic hepatitis C and IBS. We enrolled 81 patients with chronic hepatitis C, 42 with IBS and 44 healthy subjects. Fatigue was evaluated using the Fatigue Impact Scale questionnaire. Body composition was assessed through impedance analysis. Plasma carnitine and leptin were measured. Fatigue scores were significantly more elevated in patients with chronic hepatitis C and IBS than in healthy subjects. Patients with chronic hepatitis C but not IBS, had significant lower plasma levels of total and free carnitine adjusted for fat mass compared with healthy subjects. In patients with chronic hepatitis C and not with IBS, fatigue scores were negatively correlated with plasma levels of carnitine. Levels of free carnitine were significantly and independently associated with the severity of fatigue in patients with chronic hepatitis C [OR=2.019, P=0.02, CI 95% (1.01-1.23)]. In patients with chronic hepatitis C, the severity of fatigue is associated with a low level of carnitine, suggesting that an oral supplementation may be effective to relieve fatigue in chronic hepatitis C. The underlying mechanism of fatigue in IBS does not seem to involve carnitine.

Carnitine and coenzyme Q10 levels in individuals with Prader–Willi syndrome

Carnitine deficiency or coenzyme Q10 (CoQ10) deficiency may present with hypotonia, poor growth, easy fatigability, and apnea. This constellation of findings can also be seen in individuals with Prader-Willi syndrome (PWS). Animal studies indicate that increased fat mass due to obesity negatively correlates with both carnitine and CoQ10 levels in skeletal muscle. Increased body fat and obesity are characteristic of individuals with PWS. Currently, there is no documentation of serum carnitine levels, and only one study investigating plasma CoQ10 levels, in individuals with PWS. Fasting serum carnitine and plasma CoQ10 levels were measured in 40 individuals with molecularly confirmed PWS (ages 1-27 years; 19 F/21 M), 11 individuals with early-onset morbid obesity of unknown etiology (ages 3-13 years; 5 F/6 M), and 35 control siblings from both groups (ages 1-24 years; 19 F/16 M). There were no significant differences among the three groups in either total carnitine, free carnitine, or CoQ10 levels. However, individuals with PWS had higher serum levels of carnitine esters (P = 0.013) and higher ester-to-free carnitine ratios (P = 0.0096) than controls suggesting a possible underlying impairment of peripheral carnitine utilization and mitochondrial energy metabolism in some individuals with PWS. Serum sampling identified no significant differences in total and free carnitine or CoQ10 levels between individuals with PWS, obese individuals, and sibling control groups. Muscle biopsy or measurement in leukocytes or cultured skin fibroblasts could be a better method to identify abnormalities in carnitine and CoQ10 metabolism in individuals with PWS than peripheral blood sampling.

Postnatal variations in blood free and acylcarnitines

Alteration in concentrations of blood carnitine and its esters are diagnostic of a number of inherited metabolic disorders. Acylcarnitine (AC) profiles of newborns obtained from dried blood spots by tandem mass spectrometric analysis are being used for the diagnosis of these disorders. There are no data of the postnatal variations of free carnitine (FC) and AC in Indian neonates. Evaluation of postnatal variations in free and AC levels in newborns. Blood FC and AC levels were evaluated in 2,727 healthy neonates of postnatal day 2-30 by electrospray ionization tandem mass spectrometry. Blood C2, C5DC, C16, C16:1, C18, C18:1, C18:2, and C18:OH carnitines were increased in groups A (aged 8-14 days) and B (aged 15-30 days), compared with the control group (aged 2-7 days), whereas C3, C4, C4OH, C6, C6DC, and C12 carnitines were increased only in group B. No sex-related differences were found except for C3DC, C4, and C5 carnitine concentrations, which were higher in female neonates. Our data can be used as a reference for the assessment of carnitine status in Indian newborns, hence reducing the risk of misdiagnosis of fatty acid oxidation disorders and organic acidemias during interpretation of the results of tandem mass spectrometry-based newborn screening.

Recognizing and Treating Valproic Acid Toxicity: A Case Report

Valproic Acid (VPA) toxicity has been steadily increasing in frequency since the FDA approved the drug for acute mania in 1995. According to the 2005 Annual Report of the American Association of Poison Control Center's Toxic Exposure Surveillance System (TESS), 8705 acute exposures to valproic acid occurred with major adverse outcomes reported in 404 patients of this cohort. Recognizing VPA toxicity is the first step in properly managing the patient. Key signs and symptoms of VPA toxicity include: CNS depression, lethargy and potential encephalopathy, respiratory depression, nausea/vomiting, and myoclonus. Lab abnormalities often include, in addition to elevated serum VPA levels, hypernatremia, elevated anion gap metabolic acidosis, hyperosmolality, hypocalcemia, and hyperammonemia with a transaminitis. A non-contrast head CT may demonstrate cerebral edema, the peak occurrence of which is between 12 hours and 4 days after ingestion. Activated charcoal can be given early if the timing of overdose is known. Serial head CT scans should be ordered to monitor the possible delayed side effect of cerebral edema. Other areas of treatment deal with correcting the ill effects of the metabolic abnormalities (e.g. replace calcium if hypocalcemia). Specifically, lactulose is used to decrease serum ammonia levels and reduce the risk of encephalopathy. Another mainstay of treatment, L-carnitine, increases levels of free carnitine to participate in mitochondrial fatty acid synthesis. In extreme cases, hemodialysis may be required to reduce the levels of VPA and the associated metabolites. Of note our patient presented with virtually all the lab abnormalities and symptoms typical of VPA toxicity. He improved with hemodialysis and was discharged to a mental health facility in stable condition. Though VPA toxicity occurs rarely, it has a consistent presentation, symptomotology and defined treatment regimen. Awareness of a typical patient’s presentation would assist in early diagnosis and a successful treatment. J Med Cases. 2011;2(5):185-187 doi: https://doi.org/10.4021/jmc234w

A prospective double-blind, randomized clinical trial of levocarnitine to treat autism spectrum disorders

SummaryBackgroundL-carnitine was proposed as a potential treatment for patients diagnosed with an autism spectrum disorder to improve mitochondrial dysfunction, but no prior randomized controlled trials have been conducted.Material/MethodsThirty subjects diagnosed with an ASD were randomly assigned to receive a standardized regimen (50 mg L-carnitine/kg bodyweight/day) of liquid L-carnitine (n=19) or placebo (n=11) for 3-months. Measures included changes in professionally completed Childhood Autism Rating Scale (CARS), hand muscle testing, and modified clinical global impression (CGI) forms; parent completed Autism Treatment Evaluation Checklist (ATEC), treatment adherence measurement (TAM), frequency and intensity of side effect rating (FISER)/global rating of side effect burden (GRSEB)/patient report of incidence of side effects (PRISE) forms; and lab testing.ResultsSignificant improvements were observed in CARS (−2.03, 95% CI=−3.7 to −0.31), CGI (−0.69, 95% CI=−1.1 to −0.06), and ATEC scores. Significant correlations between changes in serum free-carnitine levels and positive clinical changes were observed for hand muscle strength (R2=0.23, P=0.046), cognitive scores (R2=0.27, P=0.019), and CARS scores (R2=0.20, P=0.047). Study subjects were protocol-compliant (average adherence was >85%) and generally well-tolerated the L-carnitine therapy given.ConclusionsL-carnitine therapy (50 mg/kilogram-bodyweight/day) administered for 3-months significantly improved several clinical measurements of ASD severity, but subsequent studies are recommended.

Clinical, biochemical, and molecular analysis of combined methylmalonic acidemia and hyperhomocysteinemia (cblC type) in China

The most common inborn error of cobalamin (cbl) metabolism in China is the cblC type characterized by combined methylmalonic acidemia and hyperhomocysteinemia. The clinical presentation is relatively nonspecific, such as feeding difficulty, recurrent vomiting, hypotonia, lethargy, seizures, progressive developmental delay, and mental retardation, together with anemia and metabolic acidosis. More specific biochemical findings include high levels of propionylcarnitine (C3), free carnitine (C3/C0), and acetylcarnitine (C3/C2) measured by tandem mass spectrometry (MS/MS), elevation of methylmalonic acid (MMA) measured by gas chromatography-mass spectrometry (GC-MS), and increased total homocysteine with normal or decreased methionine. We report on 50 Chinese patients with combined methylmalonic acidemia and hyperhomocysteinemia. Forty-six belonged to the cblC complementation group. Mutation analysis of the MMACHC gene was performed to characterize the mutational spectrum of cblC deficiency, and 17 different mutations were found. Most were clustered in exons 3 and 4, accounting for 91.3% of all mutant alleles. Two mutations were novel, namely, c.315C>G (p.Y105X) and c.470G>C(p.W157S). In terms of genotype-phenotype correlation, the c.609G>A mutation was associated with early-onset disease when homozygous. Unlike previous reports from other populations, c.609G>A (p.W203X) was the most frequent cblC mutation detected in our study of Chinese patients, affecting 51 of 92 MMACHC alleles (55.4%). The high prevalence of this nonsense mutation could have potential therapeutic significance for Chinese cblC patients. Besides traditional approaches consisting of hydroxocobalamin injections, carnitine, betaine, and protein restriction, novel drugs that target premature termination codons may have a role in the future.

An Unusual Case of Feeding Intolerance in a 7 Month Old Female

Purpose: Background: Aromatic L-amino acid decarboxylase deficiency (AADC) is an inborn error in neurotransmitter metabolism caused by mutations in the dopa decarboxylase (aromatic L-amino acid decarboxylase) gene, which leads to combined serotonin and catecholamine deficiency. Symptoms include severe developmental delay, hypotonia, muscle stiffness, athetosis, lethargy, feeding intolerance, sleep disturbances, oculogyric crises, extreme irritability, pain, muscle spasms, and uncontrolled movements. Patient: A 7 month old Caucasian female with a history of hypotonia and developmental motor delay presented with excessive irritability and feeding intolerance. Clinical Course: She was well until 3-4 months of age, when she became inconsolable, had non-bilious, non-bloody emesis, and irritability with feeds. Symptoms worsened over the last 3 months. She had decreased activity, poor eye tracking, and hypotonia. Initial workup showed normal gastric emptying scan, MBS revealing frank aspiration, and pH probe showed copious reflux, so a Nissen fundoplication with gastric feeding tube was placed. Lorazepam and phenobarbital did not have a perceived effect. Additional workup included an EEG, head CT scan, head MRI, karyotype, serum lactate level, serum ammonia level, and plasma amino acids which were all within normal limits except for a low cysteine level. Urine organic acids showed minimal dicarboxylic acids and acetylcarnitine profile showed a mildly elevated C4OH due to diet or a ketotic state. Magnetic resonance spectroscopy (MRS) was notable for nonspecific lactate spikes. Because of suspicion of a possible mitochondrial or neurotransmitter disorder, a lumbar puncture was performed. Neurotransmitter analysis and plasma enzymology confirmed the diagnosis of AADC. Pyridoxal-5-phosphate (coenzyme B6) and ropinirole (a dopamine agonist) were added, in addition to hyoscyamine, pantoprazole, and sucralfate. Two months after diagnosis, she has been tolerating feeds with less irritability. Conclusion: Children with feeding disorder, developmental delay and hypotonia should have a work-up for inborn errors of metabolism. Initial laboratory workup should include CBC, electrolytes, LFTs, urine organic acids, blood amino acids and acylcarnitine profile, total and free carnitine levels, as well as an MRI and MRS.

Two inborn errors of metabolism in a newborn: Glutaric aciduria type I combined with isobutyrylglycinuria

Background Glutaric aciduria type 1 (GA1) is an inborn error in the metabolism of the amino acids tryptophan, lysine and hydroxylysine due to mutations in the GCDH gene coding for glutaryl-CoA dehydrogenase. Affected individuals often suffer from an encephalopathic crisis in infancy or childhood which results in acute striatal injury leading to a severe dystonic–dyskinetic movement disorder. Isobutyryl-coenzyme dehydrogenase (IBD) is an enzyme encoded by the ACAD8 gene and involved in the catabolism of the branched-chain amino acid valine. Both GA1 and IBD deficiency can be detected by expanded newborn screening using tandem-mass spectrometry, if they are considered screening targets. Methods Tandem-mass spectrometry and gas-chromatography with mass-selective detection were used for the assessment of key metabolites in body fluids of a patient with abnormal findings in newborn screening. Mutations were investigated by direct sequencing and by restriction fragment lengths analysis. Valine metabolism was studied in vitro in immortalized lymphocytes. Results Following accumulation of acylcarnitines C5DC and C4, of 3-hydroxyglutaric acid and isobutyrylglycine in body fluids, sequence analysis in the GCDH gene revealed homozygosity for a missense mutation in exon 6, c.482G > A, p.Arg161Gln, which had been reported in GA1 before. In the ACAD8 gene a novel mutation c.841+3G > C was identified, which results in loss of exon 7 and predicts a premature stop of translation. Impaired valine degradation was corroborated by the increased post-load level of acylcarnitine C4 in lymphocytes. Conclusion The molecular basis of two inborn errors of metabolism in a newborm was elucidated. The metabolite studies underline the use of urinary C4 acylcarnitine as a sensitive marker of IBD deficiency. A functional test of IBD activity in lymphocytes may replace more invasive fibroblast studies. In view of the combination of two organic acidurias, which may both affect the level of free carnitine, careful follow-up including regular assessment of the carnitine status of the patient appears prudent.

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.

Useful second‐tier tests in expanded newborn screening of isovaleric acidemia and methylmalonic aciduria

Common use of pivalate-generating antibiotics in newborns in Japan and low cutoff value of C5-acylcarnitine (C5) to detect mild forms of isovaleric acidemia (IVA) led to 1,065 positive results from IVA screening among 146,000 newborns tested by tandem mass spectrometry over the last 3 years. Using our method to determine isovalerylglycine (IVG) levels in dried blood spots (DBS) as a second-tier test with IVG cutoff value of 0.5 nmol/ml in DBS, one patient with severe IVA was identified, and no recall of the second DBS was needed. Retrospective analysis revealed that most patients with moderate to severe forms of IVA have decreased free-carnitine levels shortly after birth and higher levels of IVG than those of C5, which suggests that this method is useful in evaluating the severity of IVA. Another second-tier test, to measure methylmalonic acid (MMA) levels in DBS by gas chromatography/mass spectrometry (GC/MS), has been developed to overcome difficulties in screening methylmalonic aciduria (MMAU) and propionic acidemia. Methanol extract from DBS was dried and derivatized using N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide. GC/MS was performed using splitless injection, electron-impact ionization, and selected ion monitoring for data recording. MMAU patients had much higher DBS concentrations of MMA (24.2-321.9 nmol/ml) than control newborns (0.34 ± 0.11 nmol/ml). MMA measurement in DBS was thought to provide useful information about the severity of MMAU, as MMAU patients with high levels of MMA had decreased levels of free carnitine and mildly increased levels of propionylcarnitine.