Autoimmune Thyroiditis, Pernicious Anaemia, Vitiligo and Scleroatrophic Lichen in a boy with short-chain acylCoA dehydrogenase deficiency.

Short-chain acylCoA dehydrogenase (SCAD) deficiency is a rare mitochondrial disorder involving the beta-oxidation of fatty acylCoA compounds in chains of 4-6 carbons. Unlike other mitochondrial disorders, cases involving autoimmune diseases have not been described. We report a 15-year-old boy with SCAD deficiency who suffered from pernicious anaemia, vitiligo, scleroatrophic lichen and autoimmune thyroiditis. As has been reported in other mitochondrial disorders, we hypothesised that autoimmune diseases are also present in SCAD deficiency. Furthermore, we discuss the possible pathogenetic relationship between these diseases.

Promotion of lipid and protein oxidative damage in rat brain by ethylmalonic acid.

High concentrations of ethylmalonic acid are found in tissues and biological fluids of patients affected by ethylmalonic encephalopathy, deficiency of short-chain acyl-CoA dehydrogenase activity and other illnesses characterized by developmental delay and neuromuscular symptoms. The pathophysiological mechanisms responsible for the brain damage in these patients are virtually unknown. Therefore, in the present work we investigated the in vitro effect of EMA on oxidative stress parameters in rat cerebral cortex. EMA significantly increased chemiluminescence and thiobarbituric acid-reactive species levels (lipoperoxidation), as well as carbonyl content and oxidation of sulfhydryl groups (protein oxidative damage) and DCFH. EMA also significantly decreased the levels of reduced glutathione (non-enzymatic antioxidant defenses). In contrast, nitrate and nitrite levels were not affected by this short organic acid. It is therefore presumed that oxidative stress may represent a pathomechanism involved in the pathophysiology of the neurologic symptoms manifested by patients affected by disorders in which EMA accumulates.

Biochemical correction of short-chain acyl-coenzyme A dehydrogenase deficiency after portal vein injection of rAAV8-SCAD.

Recombinant adeno-associated viral vectors pseudotyped with serotype 5 and 8 capsids (AAV5 and AAV8) have been shown to be efficient gene transfer reagents for the liver. We have produced AAV5 and AAV8 vectors that express mouse short-chain acyl-CoA dehydrogenase (mSCAD) cDNA under the transcriptional control of the cytomegalovirus-chicken beta-actin hybrid promoter. We hypothesized that these vectors would produce sufficient hepatocyte transduction (after administration via the portal vein) and thus sufficient SCAD enzyme to correct the phenotype observed in the SCAD-deficient (BALB/cByJ) mouse, which includes elevated blood butyrylcarnitine and hepatic steatosis. Ten weeks after portal vein injection into 8-week-old mice, AAV8-treated livers contained acyl-CoA dehydrogenase activity (14.3 mU/mg) toward butyryl-CoA, compared with 7.6 mU/mg in mice that received phosphate-buffered saline. Immunohistochemistry showed expression of mSCAD within rAAV8-mSCAD-transduced hepatocytes, as seen by light microscopy. A significant reduction of circulating butyrylcarnitine was seen in AAV5-mSCAD- and AAV8-mSCAD-injected mice. Magnetic resonance spectroscopy of fasted mice demonstrated a significant reduction in relative lipid content within the livers of AAV8-mSCAD-treated mice. These results demonstrate biochemical correction of SCAD deficiency after AAV8-mediated SCAD gene delivery.

Brain malformation and infantile spasms in a SCAD deficiency patient.

This report presents a case of short-chain acyl-coenzyme A (CoA) dehydrogenase deficiency with a previously unreported presentation with brain malformations and infantile spasms. This female infant developed repeated tonic clonic seizures at the age of 3(1/2) months. She subsequently developed West syndrome at the age of 4 months. Her electroencephalogram disclosed hypsarrhythmia, and video-electroencephalographic monitoring confirmed the presence of infantile spasms. Magnetic resonance imaging revealed a small midline frontal meningocele, abnormal cortical gyration, and partial agenesis of the corpus callosum consistent with neuronal migrational disorder. Metabolic evaluation indicated ethylmalonic acidemia. Muscle biopsy with enzymatic assay of short-chain acyl-coenzyme A revealed low enzymatic activity confirming the diagnosis of short-chain acyl-coenzyme A dehydrogenase deficiency. To our knowledge, this is the first report of the coexistence of short-chain acyl-coenzyme A dehydrogenase deficiency, infantile spasms, and brain malformation. We conclude that short-chain acyl-coenzyme A dehydrogenase deficiency should be considered in the differential diagnosis of gyral abnormality, corpus callosal hypoplasia, and infantile spasms.

Approach to management of malignant hyperthermia-like syndrome in pediatric diabetes mellitus.

BACKGROUND: Hyperglycemic hyperosmolar nonketotic syndrome (HHNS) is usually associated with type 2 diabetes mellitus and is rare in children. However, a fatal malignant hyperthermia-like syndrome (MHLS) with rhabdomyolysis associated with new-onset diabetes mellitus and HHNS in adolescents has been described. DESIGN/METHODS: Case series. RESULTS: A 16-yr-old obese male (case A) and a 10-yr-old mid-pubertal nonobese female (case B) presented within a 6-month period with emesis, altered mental status, blood glucose >1600 mg/dL, and laboratory evidence of rhabdomyolysis. Case A developed fever after initiation of insulin therapy, along with refractory hypotension and multiorgan failure. He died 14 hrs after admission. Case B developed fever before insulin therapy, was treated with dantrolene, and made a full recovery. Metabolic workup showed evidence of short-chain acyl-CoA dehydrogenase (SCAD) deficiency. CONCLUSIONS: We report two cases of malignant hyperthermia-like syndrome associated with HHNS in adolescents. Their respective fluid management and clinical courses are described. Dantrolene therapy should be initiated immediately after this syndrome is recognized. We believe it is unlikely insulin is the sole trigger for MHLS. Case B is unique in that there was evidence of SCAD deficiency, a metabolic defect that we propose could lead to MHLS. We recommend that all patients with HHNS and MHLS be evaluated for an underlying metabolic disorder.

Systemic correction of a fatty acid oxidation defect by intramuscular injection of a recombinant adeno-associated virus vector.

Mitochondrial beta-oxidation of fatty acids is required to meet physiologic energy requirements during illness and periods of fasting or physiologic stress, and is most active in liver and striated muscle. Acyl-CoA dehydrogenases of varying chain-length specificities represent the first step in the mitochondria for each round of beta-oxidation, each of which removes two-carbon units as acetyl-CoA for entry into the tricarboxylic acid cycle. We have used recombinant adeno-associated virus (rAAV) vectors expressing short-chain acyl-CoA dehydrogenase (SCAD) to correct the accumulation of fatty acyl-CoA intermediates in deficient cell lines. The rAAV-SCAD vector was then packaged into either rAAV serotype 1 or 2 capsids and injected intramuscularly into SCAD-deficient mice. A systemic effect was observed as judged by restoration of circulating butyryl- carnitine levels to normal. Total lipid content at the injection site was also decreased as demonstrated by noninvasive magnetic resonance spectroscopy (MRS). SCAD enzyme activity in the injected muscle was found at necropsy to be above the normal control mouse level. This study is the first to demonstrate the systemic correction of a fatty acid oxidation disorder with rAAV and the utility of MRS as a noninvasive method to monitor SCAD correction after in vivo gene therapy.

Misfolding, degradation, and aggregation of variant proteins. The molecular pathogenesis of short chain acyl-CoA dehydrogenase (SCAD) deficiency.

Short chain acyl-CoA dehydrogenase (SCAD) deficiency is an inborn error of the mitochondrial fatty acid metabolism caused by rare variations as well as common susceptibility variations in the SCAD gene. Earlier studies have shown that a common variant SCAD protein (R147W) was impaired in folding, and preliminary experiments suggested that the variant protein displayed prolonged association with chaperonins and delayed formation of active enzyme. Accordingly, the molecular pathogenesis of SCAD deficiency may rely on intramitochondrial protein quality control mechanisms, including degradation and aggregation of variant SCAD proteins. In this study we investigated the processing of a set of disease-causing variant SCAD proteins (R22W, G68C, W153R, R359C, and Q341H) and two common variant proteins (R147W and G185S) that lead to reduced SCAD activity. All SCAD proteins, including the wild type, associate with mitochondrial hsp60 chaperonins; however, the variant SCAD proteins remained associated with hsp60 for prolonged periods of time. Biogenesis experiments at two temperatures revealed that some of the variant proteins (R22W, G68C, W153R, and R359C) caused severe misfolding, whereas others (R147W, G185S, and Q341H) exhibited a less severe temperature-sensitive folding defect. Based on the magnitude of in vitro defects, these SCAD proteins are characterized as folding-defective variants and mild folding variants, respectively. Pulse-chase experiments demonstrated that the variant SCAD proteins either triggered proteolytic degradation by mitochondrial proteases or, especially at elevated temperature, aggregation of non-native conformers. The latter finding may indicate that accumulation of aggregated SCAD proteins may play a role in the pathogenesis of SCAD deficiency.

The frequency of short-chain acyl-CoA dehydrogenase gene variants in the US population and correlation with the C(4)-acylcarnitine concentration in newborn blood spots.

Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is a clinically heterogeneous disorder. The clinical phenotype varies from fatal metabolic decompensation in early life to subtle adult onset, some patients remain asymptomatic. Two mutations (511C>T; 625G>A) have been described in exons 5 and 6 of the SCAD gene. Although they alter the structural and catalytic properties of the SCAD protein, these variants are not true disease-causing mutations but confer disease susceptibility. Previous studies found these gene variants to be common in Europeans. We aimed to establish the frequency of these variants in the US population and to determine whether the presence of these variants correlates with elevated butyrylcarnitine (C(4)-acylcarnitine) concentrations in newborn blood spots. Based on the analysis of 694 samples, we found that the allele frequency of the 625G>A variant was significantly higher (22%) than that of the 511C>T variant (3%). These gene variants were detected in either homozygous or compound heterozygous form in 7% of the study population. Additionally, the frequency of the 625G>A allele in the Hispanic population (30%) was significantly higher than that of the African-American (9%) and Asian (13%) subpopulations. A previously unreported variant, IVS 5 (-10) C>T, was identified in three African-American newborns (0.3%). The C(4)-acylcarnitine concentration in blood spots was significantly higher in subjects homozygous for the 625A variant when compared to those homozygous for the wild type (p<0.0001). However, none of the observed genotypes was associated with a concentration of C(4)-acylcarnitine that would be consistent with a biochemical diagnosis of SCAD deficiency.