Results: There was no correlation between thrombocyte, WBC levels and urine methylmalonic acid, methyl citrate, propionic acid excretion and blood free carnitine, methylmalonylcarnitine, propionylcarnitine levels. There was a significant negative correlation between hemoglobin and propionylcarnitine levels in both diseases (MMA:r=−0.827, p<0.001 and PA:r=−0.692, p<0.001) Conclusions: The presence of negative correlation only between blood hemoglobin levels and blood propionylcarnitine levels in both diseases suggests that propionylcarnitin may have a role at the pathophysiology of anemia in these disorders. Methylmalonic aciduria (MMA) is an inborn error of organic acid metabolism. Patients with severe disease develop many complications despite treatment; often, the disease progresses to tubulointerstitial nephritis with progressive renal failure or to severe damage of the central nervous system. Liver, kidney, or combined liver and kidney transplantation is advocated when medical treatment is ineffective. Liver or combined liver and kidney transplantation is effective to improve the metabolic decompensation; however neurological deterioration has occurred in some individuals after the transplantation. Some individuals have received only renal allografts; Lubrano et al reported a 27-year-old woman with MMA MUT0, who received a kidney transplant at age 17 years, and presented no episodes of metabolic decompensation and normal renal function after the transplantation. We report a 26-year-old Japanese male with MMA MUT0 (R93H, IVS2+5 G>A), presenting end stage renal failure. The clinical symptoms appeared at age 7 months. He progressed into renal dysfunction at age 6 years. Recently serum levels of creatinine have reached above 5 mg/dl. Kidney transplantation is scheduled in June 2011. Background: Before extended neonatal bloodspot screening (NBS), MCADD patients presented with life-threatening hypoketotic hypoglycemia. Nowadays, asymptomatic newborns are identified by NBS with novel genotypes, which have not been found in clinically ascertained patients (i.e. ACADM variants). These children are treated as classical MCADD patients, while the necessity hereof is unknown. Objective: To determine the effect of ACADM variants on enzyme activity and fasting tolerance. Methods: MCAD enzyme activities were measured in cultured skin fibroblasts from 8 subjects with ACADM variants, using different substrates. In 5 subjects, a fasting study and phenylpropionic acid loading test were performed. Results: Using phenylpropionyl-CoA, MCAD activity in fibroblasts was significantly higher in variants (mean ±SD 8.1% ±7.5) compared to classical patients (<1%). Phenylpropionic acid loading caused urinary hippuric acid excretion in subjects with ACADM variants, indicating in vivo residual MCAD enzyme activity. Upon fasting, blood glucose, free fatty acid/ketone body (KB), and KB*glucose remained normal for 15-20 hours. Conclusion: ACADM variants show residual MCAD enzyme activity in vitro and in vivo, as opposed to classical patients, correlating with normal fasting tolerance. The effect of fever on in vivo residual enzyme activity remains unknown, and follow-up studies are warranted to determine the clinical relevance of these variants. Asymptomatic very long-chain acyl-CoA dehydrogenase (VLCAD)-deficient patients are often supplemented with medium-chain triglycerides (MCT) to prevent the development of cardiomyopathy and myopathy. MCT is considered a safe dietary intervention, however, long-term observations into later adulthood are still missing. In the present study, we investigated the consequences of a long term MCT supplementation in VLCAD deficient (VLCAD−/−) mice. In vivo studies based on 1H and 13 C magnetic resonance (MR) techniques were applied to analyze noninvasively the MCT effects on abdominal fat distribution and composition as well as on liver fat. These data were subsequently correlated with serum transaminases and liver histology. In addition, hepatic biochemical markers of oxidative stress were assessed. The replacement of LCT by MCT, results in a dramatic accumulation of visceral fat and serum free fatty acids in VLCAD−/− mice followed by a profound shift in body triglyceride composition when applied over one year. Liver histology 1H MRS and biochemical analysis revealed pronounced steatosis and marked oxidative stress. MCT diet has been effective in prevention of cardiomyopathy and skeletal myopathy in FAO disorders. However, our data demonstrate that long-term MCT supplementation in the mouse model results in a severe hepatic phenotype similar to non-alcoholic steatohepatitis and metabolic syndrome. Background: LPIN1 mutations were identified as a cause of severe earlyonset rhabdomyolysis. The lipin family includes two other related members, lipin-2 and 3, which share strong homology and activity. Objectives: To determine the involvement of lipins in patients presenting with various symptoms ranging from rhabdomyolysis to myalgia at any age. Patients and Methods: LPIN1, LPIN2, LPIN3 coding regions were sequenced for 200 patients presented with rhabdomyolysis (n=170) of variable onset ranging from severe to mild (CK>or<10 000 UI/L) or myalgia without myoglobinuria (n=30). Results: 35 patients presenting with severe rhabdomyolysis, occurring before age 10 years but one, had 2 LPIN1 mutations. 86% Caucasian families shared the same intragenic deletion. 40% heterozygous relatives presented mild muscular symptoms. Muscle biopsies showed excessive lipid droplets. Rhabdomyolysis were mostly precipitated by fever. Incubation of lipin-1deficient myoblasts with pro-inflammatory cytokines leaded to significant increase of lipid droplets. Nine variants identified in milder phenotypes in either gene were non-functional in a yeast complementation assay except one. Conclusion: LPIN1-related disease, a new subtype of lipid storage myopathy, constitute a major cause of severe rhabdomyolysis in childhood and occasionally in adults. Relatives can be symptomatic. No major LPIN2/LPIN3 defects are associated with muscular diseases. Multiple Acyl-CoA dehydrogenation deficiency (MADD) is a metabolic disorder affecting fatty acid β-oxidation, resulting in a decrease of electron transference to respiratory chain. Pathophysiological mechanisms leading to clinical phenotype are believed to rely mainly on the resulting energy deficiency, although its consequences on mitochondrial function are still poorly understood. In order to bring new insights, a proteome approach was adopted. We isolated mitochondria from cultured fibroblasts, from a patient with a severe MADD presentation due to ETF-QO deficiency, characterize its mitochondrial proteome and compare it with normal controls. The used approach (2-DE-MS/MS) allowed the positive identification of 287 proteins in both patient and controls, presenting 35 of then significant differences in their relative abundance. Among the differentially expressed are proteins associated to binding/folding functions, mitochondrial antioxidant enzymes as well as proteins associated to apoptotic events. The overexpression of chaperones like Hsp60 or mitochondrial Grp75, antioxidant enzymes and apoptotic proteins reflect the mitochondrial response to a complete absence of ETF-QO. Our study provides a global perspective of the mitochondrial proteome plasticity in a severe case of MADD and highlights the main molecular pathways involved in its pathogenesis. An integrated perspective of mitochondrial plasticity face to MADD is given. Background: The physiologic role of long chain acyl-CoA dehydrogenase (LCAD) has long remained elusive. LCAD is expressed in type II pneumocytes, leading us to hypothesize that a patient with LCAD deficiency would present with congenital surfactant deficiency. Design/Methods: Term infants with unexplained respiratory distress were evaluated for known causes of congenital surfactant deficiency and had a normal genotype. Lung tissue from patient and controls were evaluated with electron microscopy for lamellar body structure as well as LCAD antigen expression using immunostaining and confocal microscopy. Genetic studies were performed. Results: One patient was identified. EM of lung tissue demonstrated eccentric deposits within the lamellar bodies. LCAD antigen was absent in patient lung tissue. Genomic DNA sequencing of patient DNA revealed a homozygous base pair change involving intron 6, causing a splicing error. At six months of age, a liver biopsy demonstrated accumulation of cis-3,4methylene-heptanoylcarnitine, likely derivative from a LCAD substrate. Conclusions: This is the first report of LCAD deficiency, presenting with a unique phenotype of congenital surfactant deficiency. MADD is an inherited disorder of fatty acid, amino acid and choline metabolism. There is good correlation between MADD disease severity and mutations in ETFA, ETFB or ETFDH. A neonate was diagnosed with severe MADD based on increased C5-C18 acylcarnitines and low (2-5% of control mean) fatty acid oxidation flux in fibroblasts. Mutation analysis revealed homozygosity for a novel c.158A>G (p.Lys53Arg) mutation in ETFDH exon 2. Surprisingly, PolyPhen analysis predicts the mutation to be benign. However, in silico analyses suggested that the mutation creates an exonic splicing silencer (ESS) motif (TAGGGA) for the splicing inhibitory protein hnRNPA1. Consistent with this, patient ETFDH cDNA showed complete exon 2 skipping, which results in removal of most of the mitochondrial targeting signal. A mutation in the APC gene also creates a TAGGGA motif and causes missplicing. This illustrates that splicing regulatory elements are general. We are currently analyzing if the TAGGGA motif functions as an hnRNPA1 dependent splicing silencer using RNA affinity purification experiments and a heterologous splicing reporter minigene.