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.

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.

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.

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.

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.

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.

Identification of mutations in the galactose-1-phosphate uridyltransferase (GALT) gene in 16 Turkish patients with galactosemia, including a novel mutation of F294Y. Mutation in brief no. 235. Online.

Classical galactosemia caused by deficiency of galactose-1-phosphate uridyltransferase (GALT) is a severe autosomal recessive disorder. We report here molecular analysis of 16 unrelated Turkish galactosemia index cases without GALT activity. Almost 84% of all mutant alleles were identified in this study. The most common molecular defect observed in the Turkish population was Q188R (replacement of glutamine-188 by arginine) (57%). In order to facilitate the determination of unknown mutations in the entire coding region of GALT, we established an approach based on GALT cDNA synthesis and direct sequencing. We have identified one novel candidate galactosemia mutation, a T-to-A transversion at the codon 294 (F294Y) in exon 9 in addition to previously reported three missense (M142K K285N, A320T), one stop codon (E340X), and one silent (L218L) mutations in galactosemia patients which reflect considerable genetic heterogeneity in the Turkish population.

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.

The effect of live measles vaccines on serum vitamin A levels in healthy children.

OBJECTIVE: Serum retinol levels have been shown to be depressed during measles infection. This study aims to demonstrate whether there is any decrease in serum vitamin A level following immunization with live viral vaccine and its relation with vaccine seroconversion in children with measles. Since many children receive measles vaccine alone or in combination with measles-mumps-rubella vaccine, we studied serum vitamin A levels and antibody levels in healthy, well-nourished children before and after immunization with monovalent and combined live attenuated measles vaccine. METHODS: The first group included 21 healthy children between the ages of 9-11 months who received live measles (Schwarz) vaccine. There were also 21 healthy children (range 14-20 months of age) who received measles-mumps-rubella Trimovax (Pasteur Merieux) vaccine. All children were tested for serum vitamin A levels before vaccination, on days 9-14 and 30-42 following both vaccinations. Measles specific antibody levels were also measured on admission and 30-42 days following vaccinations. RESULTS: In both vaccination groups, mean serum vitamin A levels reduced significantly on days 9-14, but increased slightly on days 30-42 in the measles-mumps-rubella vaccinated group (P < 0.05). The baseline and follow-up levels of mean serum vitamin A did not differ between seroconverted and nonseroconverted cases within the measles vaccinated group. CONCLUSION: Serum vitamin A levels are reduced following vaccination with monovalent and combined live attenuated measles vaccines.

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.

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.

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.

A survey of the newborn populations in Belgium, Germany, Poland, Czech Republic, Hungary, Bulgaria, Spain, Turkey, and Japan for the G985 variant allele with haplotype analysis at the medium chain Acyl-CoA dehydrogenase gene locus: clinical and evolutionary consideration.

Medium chain acyl-CoA dehydrogenase (MCAD) deficiency is an inborn error of fatty acid metabolism. It is one of the most frequent genetic metabolic disorders among Caucasian children. The G985 allele represented 90% of all the variant alleles of the MCAD gene in an extensive series of retrospective studies. To study the distribution of the G985 allele, newborn blood samples from the following countries were tested; 3000 from Germany (1/116). 1000 each from Belgium (1/77). Poland (1/98), Czech Republic (1/240). Hungary (1/168), Bulgaria (1/91), Spain (1/141). Turkey (1/216), and 500 from Japan (none). The frequency is shown in parentheses. The haplotype of G985 alleles in 1 homozygote and 57 heterozygote samples were then analyzed using two intragenic MCAD gene polymorphisms (Iaq1 and GT-repeat). The result indicated that only 1 of the 10 known haplotypes was associated with the G985 mutation, suggesting that G985 was derived originally from a single ancestral source. We made a compilation of the G985 frequencies in these countries and those in nine other European countries studied previously. The G985 distribution was high in the area stretching from Russia to Bulgaria in the east and in all northern countries in western and middle Europe, but low in the southern part of western and middle Europe. The incidence among ethnic Basques appeared to be low. This distribution pattern and the fact that all G985 alleles belong to a single haplotype suggest that G985 mutation occurred later than the delta F508 mutation of the CFTR, possibly in the neolithic or in a later period, and was brought into Europe by IndoEuropean-speaking people. The panEuropean distribution of the G985 allele, including Slavic countries from which patients with MCAD deficiency have rarely been detected, indicates the importance of raising the level of awareness of this disease.

A case of Pearson syndrome associated with multiple renal cysts.

A 41-day-old infant who had severe metabolic acidosis, anemia, bleeding, hypoglycemia, and proximal tubulopathy was diagnosed with Pearson syndrome. Fibrosis in the liver, severe iron deposition in hepatocytes, and multiple renal cortical cysts were found on postmortem examination. Southern blot analysis of mitochondrial DNA obtained from peripheral blood revealed a heteroplasmic deletion of approximately 3.5 kilobases.