Warburg and pasteur phenotypes modulate cancer behavior and therapy

Energetic pathways combine in the heart of metabolism. These essential routes supply energy for biochemical processes through glycolysis and oxidative phosphorylation. Moreover, they support the synthesis of various biomolecules employed in growth and survival over branching pathways. Yet, cellular energetics are often misguided in cancers as a result of the mutations and altered signaling. As nontransformed and Pasteur-like cells metabolize glucose through oxidative respiration when only oxygen is sufficient, some cancer cells bypass this metabolic switch and run glycolysis at higher rates even in the presence of oxygen. The phenomenon is called aerobic glycolysis or the Warburg effect. An increasing number of studies indicate that both Warburg and Pasteur phenotypes are recognized in the cancer microenvironment and take vital roles in the regulation of drug resistance mechanisms such as redox homeostasis, apoptosis and autophagy. Therefore, the different phenotypes call for different therapeutic approaches. Combined therapies targeting energy metabolism grant new opportunities to overcome the challenges. Nevertheless, new biomarkers emerge to classify the energetic subtypes, thereby the cancer therapy, as our knowledge in coupling energy metabolism with cancer behavior grows.

Identification of mutations and evaluation of cardiomyopathy in Turkish patients with primary carnitine deficiency

Primary systemic carnitine deficiency (SCD) is an autosomal recessive disorder caused by defective cellular carnitine transport. Patients usually present with predominant metabolic or cardiac manifestations. SCD is caused by mutations in the organic cation/carnitine transporter OCTN2 (SLC22A5) gene. Mutation analysis of SLC22A5 gene was carried out in eight Turkish patients from six families. Six patients presented with signs and symptoms of heart failure, cardiomyopathy, and low plasma carnitine levels, five of them with concurrent anemia. A patient with dilated cardiomyopathy had also facial dysmorphia, microcephaly, and developmental delay. Tandem MS analyses in siblings of the patients revealed two more cases with low plasma carnitine levels. SCD diagnosis was confirmed in these two cases by mutation screening. These two cases were asymptomatic but echocardiography revealed left ventricular dilatation in one of them. Carnitine treatment was started before the systemic signs and symptoms developed in these patients. Mean value of serum carnitine levels of the patients was 2.63±1.92μmol/L at the time of diagnosis. After 1year of treatment, carnitine values increased to 16.62±5.11 (p<0.001) and all responded to carnitine supplementation clinically. Mutation screening of the OCTN2 gene study in the patients revealed two novel (p.G411V, p.G152R), and four previously identified mutations (p.R254X, p.R282X, p.R289X, p.T337Pfs12X). Early recognition and carnitine supplementation can be lifesaving in this inborn error of fatty acid oxidation.

A Zinc Sulphate-Resistant Acrodermatitis Enteropathica Patient with a Novel Mutation in SLC39A4 Gene

Acrodermatitis enteropathica (AE) is a rare autosomal recessive disorder of zinc deficiency due to an abnormal intestinal zinc transporter. It is characterized by the triad of acral dermatitis, alopecia, and diarrhoea. Once AE is correctly diagnosed, patients are treated with orally administered zinc sulphate. In some patients, relapses occur during adolescence, despite the regular treatment. Here, we discuss the clinical and molecular features of a 13-year-old adolescent girl with acrodermatitis enteropathica who was resistant to high-dose zinc sulphate therapy. We successfully treated the patient with zinc gluconate and vitamin C, and we detected a novel homozygous c.541_551dup (p.Leu186fsX38) mutation in the exon 3 of her SLC39A4 gene.

Does maternal knowledge impact blood phenylalanine concentration in Turkish children with phenylketonuria?

The aim of this study was to compare the level of maternal knowledge and the blood phenylalanine (Phe) control in phenylketonuria (PKU; OMIM 261600). The study was conducted on 144 children (81 boys, 63 girls) with PKU, aged between 1 and 15 years, at Hacettepe University Ihsan Dogramaci Children's Hospital, Metabolism and Nutrition Unit. All subjects were treated with a low-Phe diet using a Phe-exchange system. A 20-question multiple-choice questionnaire was applied to the mothers to determine their knowledge about PKU and its dietary treatment. Questions in the test consisted of the knowledge about the disease (6 questions), general dietary knowledge (14 questions) and knowledge about specific exchange within the dietary questions (6 questions). The median blood Phe concentration for the previous 3-year period was used as an indicator of metabolic control. Eighty-seven children had a median blood Phe concentration above the MRC Working Party Guidelines. There was a negative correlation between maternal knowledge about exchange and median blood Phe concentration in the child (p<0.05). Maternal knowledge about a standard 15 mg Phe exchange system is correlated with dietary compliance as measured by blood Phe concentrations in our subjects. We would like to implement an easier method of measuring Phe exchanges to improve dietary knowledge in the mothers.

Audiologic findings in children with biotinidase deficiency in Turkey

OBJECTIVE

Biotinidase deficiency is an autosomal recessively inherited disorder characterized by neurological and cutaneous features, including sensorineural hearing loss. Although many features of the disorder are reversible following treatment with biotin, the hearing loss appears to be irreversible. In the present study, hearing status of patients with biotinidase deficiency is characterized in a Turkish population.

METHODS

Subjective and objective audiologic tests were performed on 20 children with profound biotinidase deficiency.

RESULTS

Sensorineural hearing loss occurs in approximately 55% of the children with biotinidase deficiency. The hearing loss varies in severity from mild to profound hearing loss. In children diagnosed immediately after birth because they had an older sibling with the disorder, statistically significant differences were found between ABR results and age of diagnosis (p<0.05). Greater prolongation in ABR latencies were observed in the late-diagnosed children compared to that in the early-diagnosed children (p<0.05).

CONCLUSION

Early diagnosis is important to prevent peripheral and central hearing loss. Children with biotinidase deficiency who have hearing loss are likely at increased risk for having speech and language problems. If hearing aids do not provide sufficient amplification, cochlear implantation may be indicated in these children. Therefore, it is important to test the hearing thresholds of these children with hearing aids and evaluate their language development.

A Turkish case with molybdenum cofactor deficiency

Molybdenum cofactor deficiency (MIM 252150) is a rare progressive neurodegenerative disorder with about 100 cases reported worldwide. We have identified a male with molybdenum cofactor deficiency and analyzed the molybdenum cofactor synthesis (MOCS)1 gene, MOCS2 gene, MOCS3 gene and GEPH gene. We homozygously identified the CGA insertion after A666 of the MOCS1 gene which produces arginine insertion at codon 222 of MOCS1A. The parents, his brother and his sister who did not have any symptoms were heterozygous for the same mutation. This region was highly conserved in various species. The N-terminal part of MOCS1 a protein is suggested to form the central core of the protein and be composed of an incomplete [(alpha/beta)6] triosephosphate isomerase (TIM) barrel with a lateral opening that is covered by the C-terminal part of the protein. The insertion is located in the loop connecting the fifth beta strand to the sixth alpha helices of the TIM barrel structure. This arginine insertion would induce the conformation change and the lack of the activity.

Early cirrhosis in a patient with type I citrullinaemia (CTLN1)

A 17-month-old girl with type I classical citrullinaemia (CTLN1) presenting with early cirrhosis and unusual ultrastructural features of the liver is reported. The patient is homozygous for a splicing mutation in intron 15 of the argininosuccinate synthase gene.

Maple syrup urine disease: mutation analysis in Turkish patients

Maple syrup urine disease (MSUD), the most frequently occurring organic acidaemia in Turkey, is caused by a deficiency of the activity of branched-chain keto acid dehydrogenase enzyme (BCKAD) complex. Mutation analysis of the E1alpha, E1beta, and E2 genes of the BCKAD complex in 12 Turkish MSUD patients yielded three disease-specific mutations and a polymorphism in the E1alpha gene, none in the E1beta gene and one mutation in the E2 gene. Among them, three missense mutations (Q80E, C213Y, T106M) and the F280F polymorphism occurring in the E1alpha gene and the splice site mutation (IVS3 - 1G>A) in the E2 gene were novel. Three of the missense mutations and the splicing mutation occurred homozygously and caused classical MSUD. One patient carried the splicing mutation homozygously and the T106M mutation in the heterozygous state; this patient is the first case having simultaneously two different mutations in two different genes in the BCKAD complex. IVS3 - IG>A splicing mutation detected on the E2 gene causes deletion of the first 14 bp of exon 3 in the mutant mRNA extending between 190 and 204 nt. The deletion spans the cleavage point between mitochondrial targeting and lipoyl-bearing site of the E2 protein.

Mutation analysis in Turkish patients with hereditary fructose intolerance

Thirteen Turkish patients with hereditary fructose intolerance (HFI) were screened for the three common mutations, A149P, A174D and N334K, in the aldolase B gene that have been detected frequently in European population. We found that nine of the patients carry the A149P mutation in both alleles, which corresponds to a frequency of about 55%. Single-strand conformation analysis of all coding exons of the gene was also performed to detect unknown mutations in four patients not carrying the three common mutations. No aberrant migration patterns were observed in these patients.

Factor V Leiden mutation in Turkish patients with homozygous cystathionine beta-synthase deficiency

Venous and arterial thromboembolism can occur in patients with homocystinuria. Resistance to activated protein C, which is caused by a single point mutation in the gene for factor V, renders an individual at risk for thrombosis. It has been suggested that coexistence of hereditary homocystinuria and factor V Leiden mutation might jointly play a role in the development of thrombosis. We analysed six patients with homocystinuria due to cystathionine beta-synthase deficiency for factor V Leiden and prothrombin G20210A mutations. Only one patient was found to have the factor V Leiden mutation in homozygous form and this patient had suffered from severe thrombosis. One patient was found to be heterozygous with no documented thrombosis. None of the patients had prothrombin G20210A mutation. We stress the necessity for screening for known thrombophilic risk factors in patients with cystathonine beta-synthase deficiency. The coexistence of the factor V Leiden mutation can cause severe thrombotic events in patients with homocystinuria.

Newborn PKU screening in Turkey: at present and organization for future

At present, pkenylketonuria screening is a national child health program in Turkey which is carried out collaboratively by the Ministry of Health and three University Children's Hospitals in Ankara, Istanbul and Izmir. Since 1986 the number of cities included in the screening program has gradually increased, now and it covers all the metropolises the country. A total of 383 babies were found with persistent hyperphenylalaninemia (1:4,172) among 1,605,582 babies screened by the Guthrie test at the Hacettepe Screening Center in Ankara. By taking into account pretreatment phenylalanine levels and phenlyalanine tolerances at five years of age, the numbers of classical and mild-moderate phenylketonuria and mild hyperphenylalaninemia cases were 216, 102 and 58, respectively. The major problems encountered in the screening program and in management of the detected cases were unsatisfactory sample collection, early discharge from maternity hospitals, difficulties in reaching some detected cases, and noncompliance with dietary therapy due to illiterate parents or to lack of social insurance. To screen and treat all newborns for phenylketonuria and to include at least hypothyroidism in the screening program, there is a need for a more disciplinary intersectoral approach than exists at present.

Molecular analysis of 16 Turkish families with DHPR deficiency using denaturing gradient gel electrophoresis (DGGE)

Dihydropteridine reductase (DHPR) catalyses the conversion of quinonoid dihydrobiopterin (qBH2) to tetrahydrobiopterin (BH4), which serves as the obligatory cofactor for the aromatic amino acid hydroxylases. DHPR deficiency, caused by mutations in the QDPR gene, results in hyperphenylalaninemia and deficiency of various neurotransmitters in the central nervous system, with severe neurological symptoms as a consequence. We have studied, at the clinical and molecular levels, 17 patients belonging to 16 Turkish families with DHPR deficiency. The patients were detected at neonatal screening for hyperphenylalaninemia or upon the development of neurological symptoms. To identify the disease causing molecular defects, we developed a sensitive screening method that rapidly scans the entire open reading frame and all splice sites of the QDPR gene. This method combines PCR amplification and "GC-clamping" of each of the seven exonic regions of QDPR, resolution of mutations by denaturing gradient gel electrophoresis (DGGE), and identification of mutations by direct sequence analysis. A total of ten different mutations were identified, of which three are known (G23D, Y150C, R221X) and the remaining are novel (G17R, G18D, W35fs, Q66R, W90X, S97fs and G149R). Six of these mutations are missense variants, two are nonsense mutations, and two are frameshift mutations. All patients had homoallelic genotypes, which allowed the establishment of genotype-phenotype associations. Our findings suggest that DGGE is a fast and efficient method for detection of mutations in the QDPR gene, which may be useful for confirmatory DNA-based diagnosis, genetic counselling and prenatal diagnosis in DHPR deficiency.

Novel mutations cause biotinidase deficiency in Turkish children

Mutation analysis was performed on DNA from 31 Turkish children with profound biotinidase deficiency who were symptomatic or ascertained by newborn screening. The 98G:del7ins3 mutation is common in clinically ascertained children in both the United States and Turkish populations, but a unique common mutation, R79C, is found only in the Turkish children identified both clinically and by newborn screening. Another frequently occurring mutation, T532M, is only observed in the Turkish newborn screening group. There are four other less frequent novel mutations identified in the Turkish population. Interestingly, the Q456H and the A171T:D444H double mutation, which are the most common mutations found in the US newborn screening population and have not been observed in symptomatic children, do occur in clinically ascertained children in the Turkish population, although the double mutation may be associated with milder and/or later-onset symptoms.

Fine mapping of the human biotinidase gene and haplotype analysis of five common mutations

Biotinidase deficiency is an autosomal recessive defect in the recycling of biotin that can lead to a variety of neurologic and cutaneous symptoms. The disease can be prevented or effectively treated with exogenous biotin. The biotinidase locus (BTD) has been maped to 3p25 by in situ hybridization. The gene has been cloned, the coding region sequenced, the genomic organization determined, and a spectrum of mutations has been characterized in more than 90 individuals with profound or partial biotinidase deficiency. We have conducted haplotype analysis of 10 consanguineous and 39 nonconsanguineous probands from the United States and 8 consanguineous probands from Turkey to localize BTD with respect to polymorphic markers on 3p and to investigate the origins of five common mutations. The inbred probands were homozygous for overlapping regions of 3p ranging in size from 1.1 to 80 cM which were flanked most narrowly by D3S1259 and D3S1293. Radiation hybrids and haplotype analysis of markers within this region suggest that BTD is located within a 0.1-cM region flanked by D3S3510 and D3S1286. The radiation hybrid data suggest that the BTD gene is oriented 5' to 3' between the centromere and the 3p telomere. Association studies indicate that the gene is closer to a third locus D3S3613 than D3S3510, two markers which cannot be resolved by existing linkage data. The BTD locus and D3S3613 must therefore lie between D3S3510 and D3S1286. Comparison of haplotypes reveals evidence for possible founder effects for four of the five common mutations.

Guanosine triphosphate cyclohydrolase I deficiency: a rare cause of hyperphenylalaninemia

Tetrahydrobiopterin (BH4) deficiencies are a heterogeneous group of disorders caused by a defect in two of the three enzymes involved in its biosynthesis or in the two recycling enzymes. Except for the deficiency of dehydratase, an enzyme catalyzing a reaction in the recycling pathway, all other variants of BH4 deficiency are characterized by developmental delay, progressive neurological deterioration, hypokinesis, drooling, swallowing difficulty, truncal hypotonia, increased limb tone, myoclonus and brisk deep tendon reflexes. A deficiency of guanosine triphosphate cyclohydrolase I (GTPCH), the first enzyme in the biosynthetic pathway of BH4, is described in a 14-month-old male infant with hyperphenylalaninemia, developmental delay, hypertonia of the extremities, seizures, feeding difficulties, and vomiting. Urinary pteridine screening revealed very low levels of neopterin and biopterin which was highly suggestive of GTPCH deficiency. Low cerebrospinal fluid concentrations of 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid concentrations, together with no detectable neopterin and decreased concentrations of biopterin and folate, agreed with the diagnosis of GTPCH deficiency. Subsequently measured neopterin and biopterin synthesis in cytokine-stimulated skin fibroblasts confirmed GTPCH deficiency, albeit indirectly. The patient showed marked improvement on a low-protein low-phenylalanine diet with neurotransmitter precursor administration. The favorable outcome in this patient clearly shows that not only newborns with elevated phenylalanine levels but also older children with neurological signs and symptoms should be screened for a BH4 deficiency in order to have maximum benefit of the treatment.

Citrullinemia. Clinical experience with 23 cases

A retrospective study was performed on the clinical outcome of 23 patients with citrullinemia diagnosed during the last 20 years in our clinic. The study group consisted of 13 patients with the neonatal form of the disease, four patients with the subacute form, five patients with the late-onset form and one with the asymptomatic form. All patients were treated with natural protein restriction, sodium benzoate and arginine administration. Almost all of the neonatal-onset patients were treated with exchange transfusions and/or peritoneal dialysis. Fourteen patients died: 11 with the neonatal form, one with the subacute form, and two with the late-onset form. The general neurological outcome of the patients who were alive was not satisfactory. Despite these results, it was concluded that the prognosis and quality of life of patients with citrullinemia might be improved with early diagnosis and appropriate therapy.

The effect of zinc-supplemented bread consumption on school children with asymptomatic zinc deficiency

BACKGROUND

Zinc deficiency has been seen in developing countries in which grain-based vegetable protein is consumed more often than animal protein. This study was done to emphasize the importance of zinc-fortified foods and to investigate bioavailability of zinc in zinc-fortified bread.

METHODS

Serum zinc concentrations in healthy 7- to 11-year-old school children were determined. In 24 of 101 children serum zinc concentrations were below 65 micrograms/ul. These 24 children with asymptomatic zinc deficiency were divided into two equal groups. The 12 children with low serum zinc concentrations received the zinc-fortified bread providing 2 mg/kg/day elemental zinc acetate for 90 days (zinc-supplemented group), whereas the other 12 children received the same quality bread with no zinc fortification (control group).

RESULTS

By the end of the period, the zinc-supplemented group had significantly higher serum and leukocyte zinc concentrations (p < 0.01) and the weight, serum albumin levels, and alkaline phosphatase increased (p < 0.01). Immune functions improved, evidenced by conversion of delayed hypersensitivity skin reactions. Zinc-fortified bread (2 mg/kg/day) caused no side effects or manifestations of zinc toxicity.

CONCLUSIONS

The results indicate that the bioavailability of zinc in the bread is satisfactory. The use of zinc-fortified bread was found to be an economical and readily accessible method to eliminate zinc deficiency and to prevent further occurrence.

Delayed-onset profound biotinidase deficiency

Children with biotinidase deficiency usually exhibit symptoms at several months to years of age. We describe four children who had symptoms later in childhood or during adolescence; they had motor limb weakness, spastic paresis, and eye problems, such as loss of visual acuity and scotomata, rather than the more characteristic symptoms observed in young untreated children with the disorder. These older children each have different mutations, but they are the same as those of children who have exhibited symptoms at an early age. Biotinidase deficiency should be considered in older children who suddenly experience limb weakness and/or spastic paresis and eye symptoms.

Isovaleric acidemia. Clinical presentation of 6 cases

A retrospective study is reported on the clinical outcome of six patients with isovaleric acidemia (IVA) diagnosed during the last 20 years at the Metabolic Unit of Hacettepe University Children's Hospital. IVA is only one of many inborn errors of metabolism that may have an acute or a late, intermittent presentation. Generally, the diagnosis cannot be made by clinical or routine clinical chemical investigations, although the odor of "sweaty feet" is a presenting symptom. An unusual urinary odor, which was present in all of our patients, should lead to a thorough screening for organic acidemia at any age. Here, we have reported six patients with IVA. Two pairs were siblings. All, except one patient, had positive family history of sibling deaths and all parents were related. In our series, only two patients presented during the neonatal period and both died during the acute crisis. The other four patients presented after the neonatal period and were categorized as having a chronic intermittent form of IVA. Two cases showed normal development despite repeated metabolic decompensations; one patient was diagnosed during the first attack, but he was mentally and motor retarded. The other one died during the metabolic crisis. The presented cases illustrate that IVA can be managed successfully once the diagnosis is made. But lack of early recognition may lead to severe psychomotor retardation or death.

Acute pancreatitis in a patient with glutaric acidemia type II

We describe a two-year-old girl who presented with coma following an upper respiratory tract infection. Nonketotic hypoglycemia, metabolic acidosis and mild hyperammonemia were detected. The urinary organic acid profile was consistent with glutaric aciduria type II. Pancreatitis was diagnosed at autopsy. Although pancreatitis has been described in a number of inborn errors of metabolism including organic acidemias, to the best of our knowledge this is the first report of acute pancreatitis occurring in glutaric acidemia type II. It was stressed, therefore, that this complication should be searched for in organic aciduria patients, and the measurement of plasma amylase and lipase levels should be added to the battery of laboratory investigations in such cases.

Hypophosphatemic vitamin-D resistant rickets associated with epidermal nevus syndrome. A case report

Epidermal nevus syndrome is characterized by congenital anomalies affecting multiple body systems, especially the skin, skeleton and central nervous system. A form of rickets/osteomalacia that is markedly resistant to treatment with vitamin D has been reported in children with this syndrome. We report the clinical and laboratory observations in a child with epidermal nevi and severe hypophosphatemic rickets/osteomalacia.

Inborn errors of biotin metabolism. Clinical and laboratory features of eight cases

There are two genetically determined biotin-dependent disorders. The first is holocarboxylase synthetase (HCS) deficiency and the second biotinidase deficiency. HCS catalyzes the reaction in which active holocarboxylases are synthesized from inactive apocarboxylases. Biotin is required for this synthesis. Biotinidase facilitates the release and recycling of free biotin. Deficiency of either HCS or biotinidase is characterized by certain neurological, cutaneous and biochemical abnormalities. In this paper, six patients with biotinidase and two patients with HCS deficiency are described. Among the most common neurological findings were hypotonia (6/8), seizures (2/6) and optic atrophy (2/8). Dermatitis and conjunctivitis were present in three and four patients, respectively. All patients had low blood pH bicarbonate levels. Serum lactate was increased in all and pyruvate in six cases. Two patients with biotinidase deficiency presented earlier than the mean age of onset previously reported in the literature. Detection of eight cases during the past few years at a single metabolic unit indicates that biotinidase deficiency is not rare in Turkey, where the frequency of some other metabolic disorders has also been reported to be high. We suggest that biotin-dependent disorders should be considered in all infants with neurological symptoms, particularly those with jerks, even if other signs such as alopecia, seborrheic dermatitis and acidosis are not evident, regardless of the age of presentation.

Classical phenylketonuria associated with Goldenhar's syndrome. A case report

Classical phenylketonuria (PKU) and Goldenhar's syndrome were diagnosed in a six-month-old male infant who was referred to Hacettepe Children's Hospital for evaluation of developmental delay. There had been epibulbar dermoids in his left eye, strabismus, bilateral multiple preauricular appendices, malar hypoplasia, micrognathia, hemifacial microsoma and high palatal vault. In addition to congenital anomalies and developmental delay, blond hair, fair skin and unusual urinary odor were noted. Ferric chloride test on his urine sample was positive, and the plasma phenylalanine level was high (34 mg/dl). Based on these clinical and biochemical findings, the diagnoses of phenylketonuria and Goldenhar's syndrome were made. To our knowledge, this is the first case with PKU and Goldenhar's syndrome.

Infantile spasms as the initial symptom of biotinidase deficiency

Two patients with biotinidase deficiency had diagnoses of infantile spasms made at 1 month of age. Biotinidase deficiency may be seen early in the neonatal period without the characteristic findings such as alopecia and seborrheic dermatitis. This diagnosis should be considered in patients with infantile spasms.

Leprechaunism (Donohue's syndrome): a case report

Features of leprechaunism, including low-birth weight, a grotesque elfin face with clubbed nose, hirsutism, large low-set ears, enlarge external genitalia, distended abdomen with emaciated extremities, and growth and motor retardation were present in a 3-month-old girl. Because of parental consanguinity in this patient, a recessive mode of inheritance seems likely.

Iminoglycinuria: a benign type of inherited aminoaciduria

The diagnosis of iminoglycinuria was established in two patients on the basis of increased urinary excretion of proline, hydroxyproline and glycine in the presence of normal plasma concentrations of these respective compounds. Routine metabolic screening was performed in these infants in order to find the cause for the developmental delay observed in one infant and the siblings deaths noted in the family of the other. These two patients gave further support to the previous suggestion that renal iminoglycinuria is a benign disorder with no recognizable clinical pattern. Its detection, therefore, requires screening programs or amino acid studies.