Serap Sivri

Phenotypic and genotypic spectrum of Turkish patients with isovaleric acidemia.

We aim to investigate the genetic basis of isovaleryl-CoA dehydrogenase (IVD) gene mutations and genotype-phenotype correlations in Turkish patients. Accordingly, bi-directional sequencing was performed to screen 26 patients with isovaleric acidemia (IVA). Nine novels (c.145delC, c.234 + 3G > C, c.506_507insT, p.Glu85Gln, p.Met147Val, p.Ala268Val, p.Ile287Met, p.Gly346Asp and p.Arg382Trp) and six previously reported (c.456 + 2T > C, p.Arg21His, p.Arg21Pro, p.Arg363Cys, p.Arg363His p.Glu379Lys) pathogenic mutations were identified. Pathogenicity of the novel mutations was supported using computational programs. No clear genotype-phenotype correlation could be determined. One of the cases with the novel c.234 + 3G > C mutation has portoseptal liver fibrosis, the clinical condition that was first reported for IVA. This study is the first comprehensive report from Turkey related to IVA genetics that provides information about the high number of disease-causing novel mutations.

Microarray based mutational analysis of patients with methylmalonic acidemia: identification of 10 novel mutations.

Methylmalonic acidemia is an autosomal recessive metabolic disorder affecting the propionate oxidation pathway in the catabolism of several amino acids, odd-chain fatty acids, and cholesterol. Methylmalonic acidemia is characterized by elevated levels of methylmalonic acid in the blood and urine. Mutations in the MUT gene, encoding methylmalonyl-CoA mutase carries out isomerization of L-methylmalonyl-CoA to succinyl-CoA, cause methylmalonic acidemia. In this study, 30 Turkish patients diagnosed with mut methylmalonic acidemia were screened for mutations using custom designed sequencing microarrays. The study resulted in detection of 22 different mutations, 10 of which were novel: p.Q132*, p.A137G, c.753+1T, p.T387I, p.Q514E, p.P615L, p.D625V, c.1962_1963delTC, p.L674F, and c.2115_2116insA. The most common, p.P615T, was identified in 28.0% of patients. These results suggest that microarray based sequencing is a useful tool for the detection of mutations in MUT in patients with mut methylmalonic acidemia.

Mutation Spectrum of Fumarylacetoacetase Gene and Clinical Aspects of Tyrosinemia Type I Disease

Tyrosinemia type I (OMIM 276700) is a rare, autosomal recessive disorder caused by a deficiency in the fumarylacetoacetate hydrolase (FAH) enzyme. This study examined the spectrum of FAH gene mutation in 32 patients with tyrosinemia type I. In addition, clinical and biochemical findings were evaluated to establish a genotype-phenotype relationship in the patients. Mutation screening was performed using a 50K custom-designed resequencing microarray chip (TR_06_01r520489, Affymetrix) and sequencing analysis. Of the 12 different mutations found, 6 are categorized as novel. Three of the mutations-IVS6-1G>A, D233V, and IVS3-3C>G-are the most common in Turkish patients, comprising 25%, 17.1%, and 12.5% of mutant alleles, respectively.Clinical evaluations suggest that the spectrum of symptoms observed in the patients with very early and early disease were of the more nonspecific form, whereas the patients with late-presenting disease had more of the distinctive form over the course of the disease. This study adds support to the notion that the D233V mutation is specific to the Turkish population.

A probable new syndrome with the storage disease phenotype caused by the VPS33A gene mutation.

We present a novel multisystem disease in two siblings with clinical features resembling a lysosomal storage disease. These included coarse face, dysostosis multiplex, respiratory difficulty, proteinuria with glomerular foamy cells, neurological involvement with developmental delays, pyramidal signs, and severe chronic anemia. Detailed enzymatic analysis for lysosomal diseases and whole-exome sequencing studies excluded known lysosomal storage diseases in the proband. Subsequently, genome-wide genotyping and exome sequencing analysis of the family indicated two large homozygous regions on chromosomes 5 and 12, and strongly suggested that a homozygous p. R498W missense mutation in the VPS33A gene might be responsible for this novel disease. Segregation analysis in family members and mutation prediction tools’ results also supported the damaging effect of the missense mutation on the function of the Vps33a protein, which plays a role in the vesicular transport system. Electron microscopic studies of the cornea of the proband showed findings supportive of dysfunction in vesicular transport. The clinical phenotype and genetic studies support the suggestion that the siblings most probably have a novel disease very likely caused by a VPS33A gene defect.

Four novel mutations in the β-galactosidase gene identified in infantile type of GM1 gangliosidosis

OBJECTIVES The aim of this study is to find out mutations of Turkish GM1 gangliosidosis patients and to make genotype-phenotype correlations. DESIGN AND METHODS β-galactosidase activities were measured by using fluorometric substrate. Mutation screening of 16 exons of β-galactosidase gene and mutation detection were done by PCR-SSCP and DNA sequencing, respectively. RESULTS Four new mutations, c.188_189insT in exon 2, c.569_570insA in exon 6, p.K142Q in exon 4, p.G190D in exon 6, and one known mutation p.P549L in exon 15, were identified in the β-galactosidase gene in 5 Turkish patients. Mutations in exons 4 and 6 are in the active site and mutation in exon is in the galactose-binding domain of the β-galactosidase gene. CONCLUSION This is the first mutational analysis performed in Turkish GM1 gangliosidosis patients and shows the molecular heterogeneity of the disease in Turkish population. All identified mutations result in severe enzyme deficiency and infantile phenotype.

Screening for mucopolysaccharidoses in the Turkish population: Analytical and clinical performance of an age-range specific, dye-based, urinary glycosaminoglycan assay.

Comprehensive analytical and diagnostic performance of urinary quantitative GAG analysis with dimethylmethylene blue (DMB) and the age-specific reference ranges were determined in Turkish population, which has a high incidence of MPSs. Precision, linearity, recovery and accuracy/trueness, limits, stability, and effect of interferents were tested according to CLSI guideline. Clinical performance was evaluated with ROC analyses including 45 MPS patients. Intra-day and inter-day precisions were <5% and <11% (CV), respectively. LoD was 9.12mg/L and LoQ was 23.3mg/L. The highest reference values for urinary GAG excretion were determined in an age-specific manner. In the 2-13years age cohort, a cut-off of 89.86mg/g creatinine resulted in 98.07% sensitivity and 93.33% specificity. Proteinuria and hematuria interfered with analysis in some instances. Neither leukocyturia nor pH changes affected the assay. Stability analysis indicated that freezing urine samples for transfer is unnecessary. Of the 45 MPS patient samples evaluated, only three tested negative including MPS II, IVA and VI. Despite limitations due to low levels of urinary GAG excretion in some cases, urinary GAG analysis with DMB with its technical simplicity, low cost, and precise quantitative results, is a valuable screening method, particularly in populations with a high rate of MPSs.

Molecular and clinical evaluation of Turkish patients with lysinuric protein intolerance.

Lysinuric protein intolerance is an autosomal recessive metabolic disorder caused by defective transport of the cationic amino acids lysine, arginine and ornithine in the epithelial cells of the basolateral membrane in the small intestine and renal tubules. Mutations in the solute carrier family 7, member 7, SLC7A7, gene cause this multisystemic disease with a variety of clinical symptoms such as hepatosplenomegaly, osteoporosis, hypotonia, developmental delay, pulmonary insufficiency or end-stage renal disease. In the present study, genomic structure of SLC7A7 in six Turkish patients with lysinuric protein intolerance was examined in order to detect disease causing mutations by denaturing high pressure liquid chromatography and direct sequencing. Four novel mutations were identified in SLC7A7: c.223insGTC, p.Val74_Ile75insVal; c.283insTGG, p.Glu94_Thr95insTrp; c.344_347delTTGC, p.Leu115LeufsX53; and c.1099insT, p.Ile367TyrfsX16. Clinical and biochemical findings were evaluated together with these molecular analyses.

Partial hydatidiform mole in a phenylketonuria patient treated with sapropterin dihydrochloride.

Abstract Strict control of hyperphenylalaninemia is necessary in pregnant women with phenylketonuria (PKU) in order to prevent phenylalanine embryopathy in the fetus, characterized by intrauterine growth restriction, dysmorphic facies, congenital heart disease, microcephaly and intellectual disability, collectively known as maternal PKU syndrome. Sapropterin dihydrochloride (SD), an alternative or adjunct to dietary therapy in patients with tetrahydrobiopterin (BH4)-responsive PKU, has recently been used in several cases to treat PKU during pregnancy with satisfactory results. Here, we report two pregnancies treated with SD and unrestricted diet in a patient with BH4-responsive mild PKU. The first pregnancy resulted in a partial hydatidiform mole and was terminated, whereas a healthy infant was born from the second pregnancy. Phenylalanine control was optimal in both pregnancies. To the best of our knowledge, this is the first report on the development of partial hydatidiform mole associated with SD treatment and the second report on molar pregnancy in PKU. While the relation between SD and molar pregnancy is unknown, further studies may be needed to investigate the possible effects of SD on fertilization.

Glutaric Aciduria Type 2 Presenting With Acute Respiratory Failure In An Adult

Glutaric aciduria (GTA) type II can be seen as late onset form with myopathic phenotype. We present a case of a 19-year old female with progressive muscle weakness was admitted in intensive care unit (ICU) with respiratory failure and acute renal failure. Patient was unconscious. Pupils were anisocoric and light reflex was absent. She had hepatomegaly. The laboratory results showed a glucose level of 70 mg/dl and the liver enzymes were high. The patient also had hyponatremia (117 mEq/L) and lactate level of 3.9 mmol/L. Tandem MS and organic acid analysis were compatible with GTA type II. Carnitine 1gr, riboflavin 100 mg and co-enzymeQ10 100 mg was arranged. After four months from beginning of treatment tandem MS results are improved. Respiratory failure, acute renal failure due to profound proximal myopathy can be due to glutaric aciduria type II that responded rapidly to appropriate therapy.

Galactosemia in the Turkish population with a high frequency of Q188R mutation and distribution of Duarte-1 and Duarte-2 variations

Classical galactosemia is an inherited recessive disorder of galactose metabolism caused by deficiency of the enzyme galactose-1-phosphate uridyl transferase (GALT), which is caused by mutations in the GALT gene. In this study, 56 Turkish patients diagnosed with galactosemia were screened for GALT gene mutations using Affymetrix resequencing microarrays. Eleven types of mutations were detected in these patients, including two novel mutations (R258G and G310fsX49) and nine recurrent mutations. We detected six patients who were homozygous for the E340* mutation and for N314D, L218L silent substitutions (Duarte-1 variant) in this study. The haplotype E340*, N314D and L218L has been reported only in Turkish patients, which suggests that the E340* mutation is specific for our population and might be spread by a Turk ancestor. In patients, the Duarte-1 allele was found with a frequency of 10.71%, whereas the Duarte-2 allele was not detected. Duarte-1 and Duarte-2 alleles were found to be present at a frequency of 2.3% and 1.4%, respectively, in the screening of 105 healthy individuals. Considering all detected mutations, it is a very important finding that exons 6 and 10 of the GALT gene account for 79% of all mutant alleles in the Turkish population. The most common mutation is Q188R, with a frequency of 55.35%.