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.