High Prevalence of c.1528G>C Rearrangement in Patients with Long Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency from Ukraine

During 2011–2016, selective screening of hereditary disorders of amino acid and acylcarnitines metabolism identified six patients with a set of clinical symptoms and biochemical markers, which indicated a high probability of one of the two hereditary disorders of fatty acids β-oxidation associated with complete deficiency of trifunctional protein (TFP) or isolated deficiency of long chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD). To differentiate these two inherited disorders, molecular genetic analysis of major missense rearrangement c.1528G>C in the HADHA gene was carried out. This mutation is associated with isolated LCHAD deficiency and the worldwide frequency of its alleles varies from 68 to 95%. As a result of this study, it was shown that this mutation was present in 100% of alleles in patients from Ukraine. Therefore, the diagnosis of isolated LCHAD deficiency was confirmed in these six patients. Thus, the preliminary frequency of isolated LCHAD deficiency in Ukraine is 1: 329968 live births at present, which is 2.1 times lower than the average for Europe.     

High vulnerability of the heart and liver to 3‐hydroxypalmitic acid–induced disruption of mitochondrial functions in intact cell systems

Patients affected by long‐chain 3‐hydroxyacyl‐CoA dehydrogenase (LCHAD) deficiency predominantly present severe liver and cardiac dysfunction, as well as neurological symptoms during metabolic crises, whose pathogenesis is still poorly known. In this study, we demonstrate for the first time that pathological concentrations of 3‐hydroxypalmitic acid (3HPA), the long‐chain hydroxyl fatty acid (LCHFA) that most accumulates in LCHAD deficiency, significantly decreased adenosine triphosphate‐linked and uncoupled mitochondrial respiration in intact cell systems consisting of heart fibers, cardiomyocytes, and hepatocytes, but less intense in diced forebrain. 3HPA also significantly reduced mitochondrial Ca²⁺ retention capacity and membrane potential in Ca²⁺‐loaded mitochondria more markedly in the heart and the liver, with mild or no effects in the brain, supporting a higher susceptibility of the heart and the liver to the toxic effects of this fatty acid. It is postulated that disruption of mitochondrial energy and Ca²⁺ homeostasis caused by the accumulation of LCHFA may contribute toward the severe cardiac and hepatic clinical manifestations observed in the affected patients.     

Allele-Specific PCR with Competitive Probe Blocking for Sensitive and Specific Detection of BRAF V600E in Thyroid Fine-Needle Aspiration Specimens

Objective: To detect BRAF V600E mutation in thyroid fine-needle aspiration (FNA) slides and needle rinses (NR). Study Design: Tumor-enriched DNA was extracted from FNA smears, formalin-fixed paraffin-embedded (FFPE) sections, or NR specimens from 37 patients with confirmed papillary thyroid carcinoma or benign findings. An allele-specific primer selectively amplified the 1799 T>A BRAF mutation while simultaneously blocking amplification of wild-type (WT) BRAF with an unlabeled probe during PCR. Mutation detection was accomplished by melting analysis of the probe. Results: Allele-specific/blocking probe PCR confirmed the BRAF mutation status for 20 of 24 paired FNA/FFPE samples previously tested by fluorescent probe real-time PCR. For the other 4 cases, the sensitive PCR method detected the BRAF mutation in all paired FNA/FFPE samples. Previously, the mutation had been detected in only the FFPE samples. The BRAF mutation was also detected in some NR specimens. Conclusion: Treatment of patients with thyroid nodules is guided by FNA biopsy, which can be scantly cellular, necessitating a sensitive test that can detect low levels of BRAF V600E mutation in a WT background. We report increased detection of BRAF V600E in FNA specimens using allele-specific/blocking probe PCR, which has an analytical sensitivity of 0.01%.     

Abnormal sodium stimulation of carnitine transport in primary carnitine deficiency

Primary carnitine deficiency is an autosomal recessive disorder of fatty acid oxidation characterized by hypoketotic hypoglycemia and skeletal and cardiac myopathy. It is caused by mutations in the sodium-dependent carnitine cotransporter OCTN2. The majority of natural mutations identified in this and other Na(+)/solute symporters introduce premature termination codons or impair insertion of the mutant transporter on the plasma membrane. Here we report that a missense mutation (E452K) identified in one patient with primary carnitine deficiency did not affect membrane targeting, as assessed with confocal microscopy of transporters tagged with the green fluorescent protein, but reduced carnitine transport by impairing sodium stimulation of carnitine transport. The natural mutation increased the concentration of sodium required to half-maximally stimulate carnitine transport (K(Na)) from the physiological value of 11.6 to 187 mm. Substitution of Glu(452) with glutamine (E452Q), aspartate (E452D), or alanine (E452A) caused intermediate increases in the K(Na). Carnitine transport decreased exponentially with increased K(Na). The E452K mutation is the first natural mutation in a mammalian cotransporter affecting sodium-coupled solute transfer and identifies a novel domain of the OCTN2 cotransporter involved in transmembrane sodium/solute transfer.     

Acyl-CoA dehydrogenase 9 (ACAD 9) is the long-chain acyl-CoA dehydrogenase in human embryonic and fetal brain

We recently reported the expression and activity of several fatty acid oxidation enzymes in human embryonic and fetal tissues including brain and spinal cord. Liver and heart showed expression of both very long-chain acyl-CoA dehydrogenase (VLCAD) and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) mRNA. However, while mRNA expression of LCHAD could be clearly detected in the retina and spinal cord, expression of VLCAD mRNA was low to undetectable in these tissues. Nevertheless, abundant acyl-CoA dehydrogenase (ACAD) activity was detected with palmitoyl-CoA as substrate in fetal central nervous tissue. These conflicting data suggested the presence of a different long-chain ACAD in human embryonic and fetal brain. In this study, using in situ hybridization as well as enzymatic studies, we identified acyl-CoA dehydrogenase 9 (ACAD 9) as the long-chain ACAD in human embryonic and fetal central nervous tissue. Until now, no clinical signs and symptoms of central nervous system involvement have been reported in VLCAD deficiency. A novel long-chain FAO defect, i.e., ACAD 9 deficiency with only central nervous system involvement, could, if not lethal during intra uterine development, easily escape proper diagnosis, since probably no classical signs and symptoms of FAO deficiency will be observed. Screening for ACAD 9 deficiency in patients with undefined neurological symptoms and/or impairment in neurological development of unknown origin is necessary to establish if ACAD 9 deficiency exists as a separate disease entity.     

Free Radical-Induced Liver Injury. I. Effects of Dietary Vitamin E Deficiency on Triacylglycerol Level and its Fatty Acid Profile in Rat Liver

Effects of dietary vitamin E deficiency on the fatty acid compositions of total lipids and phospholipids were studied in several tissues of rats fed a vitamin E-deficient diet for 4, 6, and 9 months. No significant differences were observed between the vitamin E deficiency and controls except in the fatty acid profiles of liver total lipids. Triacylglycerol (TAG) accumulation was found in the liver of rats fed a vitamin E-deficient diet. The levels of TAG-palmitate and -oleate increased particularly in the liver from such animals. The fatty acid compositions of hepatic phospholipids were not affected by the diet. Increased TAG observed in the liver of rats fed a vitamin E-deficient diet was restored to normal when the diet was supplemented with 20 mg α-tocopheryl acetate/kg diet. These findings indicate that dietary vitamin E deficiency causes TAG accumulation in the liver and that the antioxidant, vitamin E, is capable of preventing free radical-induced liver injury.     

Prevalence of known mutations in the MEFV gene in a population screening with high rate of carriers

The Familial Mediterranean Fever (FMF) shows an autosomal recessive pattern of inheritance and affects certain ethnic groups. Disease is caused by mutations in MEFV gene and more than 180 mutations have been defined in affected individuals. Current study aimed to determine the frequency-type of the mutations for MEFV gene in Sivas??middle Anatolian city. The cohort was composed of 3340 patients. MEFV gene mutations were studied by multiplex PCR based reverse hybridization stripAssay method. Patients?? clinical features were; family history: 68%, erysipelas-like erythema: 17.6%, fever: 89.9%, abdominal pain: 84.2%, peritonitis: 90.2%, arthritis: 33%, pleuritis: 14.2%, parental consanguinity: 21.2%. Current results revealed that M694V is the most frequent mutation (43.12%), followed by E148Q (20.18), M680I(G/C) (15.00%) and V726A (11.32%). The study population has a high rate of carriers and the E148Q mutation frequency was found to be highest when compared to the other regions of Turkey and other Mediterranean groups.     

Molecular Diagnosis of 21-Hydroxylase Deficiency: Detection of Four Mutations on a Single Gel

Previous studies of the molecular basis of 21-hydroxylase deficiency have shown four common gene conversion mutations in exons 7 and 8. Current molecular diagnostic protocols use allele-specific oligonucleotide hybridization (ASOH) to individually detect each of these mutations and the corresponding normal alleles. This method is costly, labor intensive, and may not provide quantitative results. To expedite molecular diagnosis in families with 21-hydroxylase deficiency, we have designed and implemented single-strand conformational polymorphism (SSCP) analysis. We applied SSCP analysis to 12 families in whom mutations in exons 7 or 8 had been previously identified by ASOH. Using a single polymerase chain reaction (PCR) amplification, unique conformers can be assigned to three mutations: V281L, Q318X, and R356W. The fourth mutation, T insertion at nucleotide 1761, was detected by heteroduplex analysis of the same PCR product. Thus, we were able to identify all four mutations using a single PCR product on a single gel.     

Non-antioxidative mechanism of cytochrome P-450 stabilization by alpha-tocopherol: the effectiveness in avitaminosis E

The efficiency of alpha-tocopherol as a 7-etoxycumarine deethylase protector in rat liver microsomes damaged by phospholipase A2 at various levels of vitamin E was studied. No selective damage of cytochrome P-450 isoforms possessing a catalytic activity towards 7-etoxycumarine under vitamin E deficiency was observed. Phospholipase A2 decreased the deethylase activity of cytochrome P-450, the efficiency of the damaging action being dependent on vitamin E content in the liver. Exogenous alpha-tocopherol exerts an antiphospholipase effect and protects 7-etoxycumarine deethylase; the protective action is inversely proportional to vitamin E level in the liver. Under normal conditions the damaging effect of phospholipase A2 on cytochrome P-450 is mainly provided for by lysophospholipids, while under vitamin E deficiency both lysophospholipids and free fatty acids exert a damaging action. A possible mechanism of the stabilizing effect of alpha-tocopherol may consist in the interaction of the chromanol nucleus in the vitamin E molecyule both with lysophospholipids and with free fatty acids.     

Characterization of two stop codon mutations in the galactose-1-phosphate uridyltransferase gene of three male galactosemic patients with severe clinical manifestation

Classical galactosemia, which is caused by deficiency of galactose-1-phosphate uridyltransferase, is characterized by acute problems of hepatocellular dysfunction, sepsis, cataracts and failure to thrive. Galactose limitation reverses these symptoms immediately; however, the long-term complications, such as mental retardation and ovarian failures are major problems in most of these patients. In order to investigate the molecular basis for phenotype variation in galactosemia, we have screened the most common mutation in the GALT gene, Q188R. We have further examined those patients who are heterozygous for Q188R or negative for this mutation by SSCP analysis and direct sequencing. In three male patients, we have identified, for the first time, two stop-codon mutations in the GALT gene, G212X (exon 7) and E340X (exon 10). Two patients of 8 and 28 years of age, respectively, who are compound heterozygotes for Q188R and G212X, have severe mental retardation and their general clinical condition is more severe than that of patients with missense mutations. The third patient, who is 8 years of age and who is homozygous for E340X, the N314D polymorphism and a silent substitution L218L, presents with a relatively normal physical and mental condition to date.     

Insertion of an extra codon for threonine is a cause of dihydropteridine reductase deficiency.

The mutation in a patient with dihydropteridine reductase deficiency has been located and characterized. Polymerase chain reaction (PCR) was used to amplify the coding sequence of human dihydropteridine reductase from the messenger RNA of skin fibroblasts. Chemical cleavage of mismatches indicated a mismatched thymine and cytosine at approximately 117 and 147 bases, respectively, from the end of the probe. Cloning and sequencing of the mutant PCR products revealed the insertion of the triplet ACT (threonine), after alanine 122 (base 390). Amplification of a small region around this mutation by using genomic DNA as the PCR target indicates that the mutation is completely within an exon. Unequal crossing-over at the second base in the preceding alanine codon and duplication of the bases CTA may be the mechanism of mutagenesis. The cleavage site 147 bases from the end of the probe corresponded to the conversion of guanine to adenine at base 420 (CTG to CTA) and does not alter the code for leucine. This change, which was also seen in another dihydropteridine reductase-deficient child and in a control subject probably represents a common neutral polymorphism.     

大肠杆菌3-酮基脂酰ACP还原酶110位天冬酰胺突变后的结构与功能

3-酮基脂酰ACP还原酶催化3-酮基脂酰ACP还原为3-羟基脂酰ACP,是细菌脂肪酸合成反应的关键酶之一.为了明确该酶中110位的保守天冬酰胺残基在酶催化活性和酶结构中的作用,本研究采用基因定点突变和蛋白质表达纯化技术,获得了大肠杆菌3-酮基脂酰ACP还原酶FabG的两个突变蛋白：FabG N110Q和FabG N110L.圆二色谱结果显示,天冬酰胺残基的突变改变了FabG的空间结构,使突变蛋白的α螺旋结构明显增加.以3-酮脂酰ACP为底物的酶活性测定表明,突变蛋白的酶活性均有下降,但残存的酶活性达到了FabG的75%以上.突变蛋白FabG N110Q和FabG N110L具有3-酮基脂酰ACP还原酶的活性,能在体外重建细菌脂肪酸合成反应.对fabG温度敏感突变株的遗传互补分析表明,FabG蛋白110位天冬酰胺突变为谷氨酰胺或亮氨酸后,在一定的条件下仍能互补大肠杆菌的生长.本研究结果提示,FabG 110位的天冬酰胺残基不是参与3-酮基脂酰ACP还原酶催化反应的必需氨基酸,它只是作为结构氨基酸,在维持FabG的空间结构的稳定性方面起作用.     

For novel gene mutations in five Japanese male patients with neonatal or late onset OTC deficiency: application of PCR-single-strand conformation polymorphisms for all exons and adjacent introns

Ornithine transcarbamylase deficiency (OTC), the most common inborn error of the urea cycle, shows an X-linked inheritance with frequent new mutations. Southern blots reveal only a small percent of the mutation, but amplification of cDNA or genomic DNA using the polymerase chain reaction (PCR) followed by DNA sequencing, has contributed greatly to overcoming this difficulty. Problems remaining are the limited availability of fresh liver samples for preparation of intact mRNA in the former case, and there are primer sequences for PCR for only some exons in the latter case. Here, we report the structures of intron sequences which are long enough to analyze all exons and adjacent introns of the OTC gene using PCR and PCR single-strand conformation polymorphisms (PCR-SSCP). We carried out a DNA analysis of findings in five Japanese male patients with neonatal or late onset form. Five patients had mutations in the protein coding region. C to G (S192R), A to T (D196V), A to G (T264A), T to C (M268T), and C to T (R277W) substitutions. The first four of these were novel missense mutations and the presence of the mutation was confirmed in the corresponding families.     

Perturbations in cerebral oxygen radical formation and membrane order following vitamin E deficiency

The effects of dietary vitamin E deficiency on mouse cerebral membrane order and oxygen reactive species were studied. Quantitation of vitamin E levels in several brain regions showed greatest deficiencies in striatum and cerebellum, followed by substantia nigra, and cortex. Vitamin E deficiency increased central-core membrane order in cerebral P2 fraction, but was without effect in the superficial hydrophilic membrane domain. Oxygen radical formation was studied using the probe 2',7'-dichlorofluorescein diacetate. Basal generation rates of oxygen reactive species were 2.5-fold higher when compared to control animals. While hepatic levels of vitamin E are much more reduced than brain levels, in deficient mice, the rate of oxygen radical formation in the liver was unaltered. This implies an special susceptibility of the brain to deficiency of this lipophilic antioxidant vitamin. Data demonstrate that endogenous levels of free radical scavengers, such as vitamin E, may play an important role in maintaining basal oxygen radical levels and membrane integrity. The dietary vitamin E depletion paradigm suggests that a relation exists between elevated levels of oxygen radicals and more rigid hydrophobic central-cores in cerebral membranes, effects that may play a role in mechanisms underlying the neuropathologic lesions observed following vitamin E deficiency.     

Effects of selenium deficiency on fatty acid metabolism in rats fed fish oil-enriched diets.

The hepatic fatty acid metabolism was investigated in rats stressed by selenium deficiency and enhanced fish oil intake. Changes in the composition of lipids, peroxides, and fatty acids were studied in the liver of rats fed either a Sedeficient (8 microg Se/kg) or a Se-adequate (300 microg Se/kg) diet, both rich in n-3 fatty acid-containing fish oil (100 g/kg diet) and vitamin E (146 mg alpha-tocopherol/kg diet). The two diets were identical except for their Se content. Se deficiency led to a decrease in hair coat density and quality as well as to changes in liver lipids, individual lipid fractions and phospholipid fatty acid composition of the liver. The low Se status did reduce total and reduced glutathione in the liver but did not affect the hepatic malondialdehyde level. In liver phospholipids (PL), Se deficiency significantly reduced levels of palmitic acid [16:0], fatty acids of the n-3 series such as DHA [22:6 n-3], and other long-chain polyunsaturates C-20-C-22, but increased n-6 fatty acids such as linoleic acid (LA) [18:2 n-6]. Thus, the conversion of LA to arachidonic acid was reduced and the ratio of n-6/n-3 fatty acids was increased. As in liver PL, an increase in the n-6/n-3 ratio was also observed in the mucosal total fatty acids of the small intestine. These results suggest that in rats with adequate vitamin E and enhanced fish oil intake, Se deficiency affects the lipid concentration and fatty acid composition in the liver. The changes may be related to the decreased levels of selenoenzymes with antioxidative functions. Possible effects of Se on absorption, storage and desaturation of fatty acids were also discussed.