Person: GÜRAN, TÜLAY
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GÜRAN
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TÜLAY
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Publication Open Access Sphingosine-1-phosphate lyase (SGPL1) deficiency is associated with mitochondrial dysfunction(PERGAMON-ELSEVIER SCIENCE LTD, 2020-09) GÜRAN, TÜLAY; Maharaj, A.; Williams, J.; Bradshaw, T.; Guran, T.; Braslavsky, D.; Casas, J.; Chan, L. F.; Metherell, L. A.; Prasad, R.Deficiency in Sphingosine-1-phosphate lyase (S1P lyase) is associated with a multi-systemic disorder incorporating primary adrenal insufficiency (PAI), steroid resistant nephrotic syndrome and neurological dysfunction. Accumulation of sphingolipid intermediates, as seen with loss of function mutations in SGPL1, has been implicated in mitochondrial dysregulation, including alterations in mitochondrial membrane potentials and initiation of mitochondrial apoptosis. For the first time, we investigate the impact of S1P lyase deficiency on mitochondrial morphology and function using patient-derived human dermal fibroblasts and CRISPR engineered SGPL1-knockout HeLa cells. Reduced cortisol output in response to progesterone stimulation was observed in two patient dermal fibroblast cell lines. Mass spectrometric analysis of patient dermal fibroblasts revealed significantly elevated levels of sphingosine-1-phosphate, sphingosine, ceramide species and sphingomyelin when compared to control. Total mitochondrial volume was reduced in both S1P lyase deficient patient and HeLa cell lines. Mitochondrial dynamics and parameters of oxidative phosphorylation were altered when compared to matched controls, though differentially across the cell lines. Mitochondrial dysfunction may represent a major event in the pathogenesis of this disease, associated with severity of phenotype.Publication Open Access A Rare Cause of Hypophosphatemia: Raine Syndrome Changing Clinical Features with Age(SPRINGER, 2020-07) DAĞÇINAR, ADNAN; Eltan, Mehmet; Alavanda, Ceren; Yavas Abali, Zehra; Ergenekon, Pinar; Yalindag Ozturk, Nilufer; Sakar, Mustafa; Dagcinar, Adnan; Kirkgoz, Tarik; Kaygusuz, Sare Betul; Gokdemir, Yasemin; Elcioglu, Huriye Nursel; Guran, Tulay; Bereket, Abdullah; Ata, Pinar; Turan, SerapRaine Syndrome (RS) is caused by biallelic loss-of-function mutations in FAM20C gene and characterized by hypophosphatemia, typical facial and skeletal features. Subperiosteal bone formation and generalized osteosclerosis are the most common radiological findings. Here we present a new case with RS. A 9-month-old male patient on a home-type ventilator was referred for hypophosphatemia. He was born with a weight of 3800 g to non-consanguineous parents. Prenatal ultrasound had demonstrated nasal bone agenesis. A large anterior fontanel, frontal bossing, exophthalmos, hypoplastic nose, high arched palate, low set ears, triangular mouth, and corneal opacification were detected on physical examination. Serial skeletal X-rays revealed diffuse osteosclerosis at birth which was gradually decreased by the age of 5 months with subperiosteal undermineralized bone formation and medullary space of long bone could be distinguishable with bone-within-a-bone appearance. At 9 months of age, hand X-ray revealed cupping of the ulna with loose radial bone margin with minimal fraying and osteopenia. Cranial computed tomography scan showed bilateral periventricular calcification and hydrocephalus in progress. The clinical, laboratory, and radiological examinations were consistent with RS. Molecular analyses revealed a compound heterozygous mutation in FAM20C gene (a known pathogenic mutation, c.1645C > T, p.Arg549Trp; and a novel c.863 + 5 G > C variant). The patient died due to respiratory failure at 17 months of age. This case allowed us to demonstrate natural progression of skeletal features in RS. Furthermore, we have described a novel FAM20C variant causing RS. Previous literature on RS is also reviewed.Publication Open Access Familial Hypomagnesemia with Hypercalciuria and Nephrocalcinosis Due to CLDN16 Gene Mutations: Novel Findings in Two Cases with Diverse Clinical Features(SPRINGER, 2021-11-11) BEREKET, ABDULLAH; Eltan, Mehmet; Abali, Zehra Yavas; Turkyilmaz, Ayberk; Gokce, Ibrahim; Abali, Saygin; Alavanda, Ceren; Arman, Ahmet; Kirkgoz, Tarik; Guran, Tulay; Hatun, Sukru; Bereket, Abdullah; Turan, SerapBiallelic loss of function mutations in the CLDN16 gene cause familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC), and chronic kidney disease. Here we report two cases of FHHNC with diverse clinical presentations and hypercalcemia in one as a novel finding. Pt#1 initially presented with urinary tract infection and failure to thrive at 5.5 months of age to another center. Bilateral nephrocalcinosis, hypercalcemia (Ca: 12.2 mg/dl), elevated parathyroid hormone (PTH) level, and hypercalciuria were detected. Persistently elevated PTH with high/normal Ca levels led to subtotal-parathyroidectomy at the age of 2.5. However, PTH levels remained elevated with progressive deterioration in renal function. At 9-year-old, she was referred to us for evaluation of hyperparathyroidism and, hypomagnesemia together with hypercalciuria, elevated PTH with normal Ca levels, and medullary nephrocalcinosis were detected. Compound heterozygosity of CLDN16 variants (c.715G>A, p.G239R; and novel c.360C>A, p.C120*) confirmed the diagnosis. Pt#2 was a 10-month-old boy, admitted with irritability and urinary crystals. Hypocalcemia, hypophosphatemia, elevated PTH and ALP, low 25(OH)D levels, and radiographic findings of rickets were detected. However, additional findings of hypercalciuria and bilateral nephrocalcinosis were inconsistent with the nutritional rickets. Low/normal serum Mg levels suggested the diagnosis of FHHNC which was confirmed genetically as a homozygous missense (c.602G > A; p.G201E) variant in CLDN16. Yet, hypocalcemia and hypomagnesemia persisted in spite of treatment. In conclusion, FHHNC may present with diverse clinical features with mild hypomagnesemia leading to secondary hyperparathyroidism with changing Ca levels from low to high. Early and accurate clinical and molecular genetic diagnosis is important for proper management.Publication Open Access Homozygosity for a novel INHA mutation in two male siblings with hypospadias, primary hypogonadism, and high-normal testicular volume(2022-03-23) ŞAHİN, BAHADIR; DEMİRCİOĞLU, SERAP; BEREKET, ABDULLAH; GÜRAN, TÜLAY; Arslan Ateş E., Eltan M., Sahin B., Gurpinar Tosun B., Seven Menevse T., Geckinli B. B., Greenfield A., Turan S., Bereket A., Güran T.Background: The human INHA gene encodes the inhibin subunit alpha protein, which is common to both inhibin A and B. The functional importance of inhibins in male sex development, sexual function, and reproduction remain largely unknown. Objective: We report for the first time two male siblings with homozygous INHA mutations. Methods: The medical files were examined for clinical, biochemical, and imaging data. Genetic analysis was performed using next-generation and Sanger sequencing methods. Results: Two brothers complained of gynecomastia, testicular pain, and had a history of hypospadias. Biochemistry revealed low serum testosterone, high gonadotropin and anti-Mullerian hormone, and very low/undetectable inhibin concentrations, where available. Both patients had azoospermia in the spermiogram. We have identified a homozygous 2 bp deletion (c.208_209delAG, R70Gfs*3) variant, which leads to a truncated INHA protein in both patients, and confirmed heterozygosity in the parents. The external genital development, pubertal onset and progression, reproductive functions, serum gonadotropins, and sex hormones of mother and father, who were heterozygous carriers of the identified mutation, were normal. Conclusion: Homozygosity for INHA mutations causes decreased prenatal and postnatal testosterone production and infertility in males, while the heterozygous female and male carriers of INHA mutations do not have any abnormality in sex development and reproduction.Publication Open Access Biallelic and monoallelic ESR2 variants associated with 46,XY disorders of sex development(2018-07) BEREKET, ABDULLAH; Baetens, Dorien; Güran, Tülay; Mendonca, Berenice B.; Gomes, Nathalia L.; De Cauwer, Lode; Peelman, Frank; Verdin, Hannah; Vuylsteke, Marnik; Van der Linden, Malaïka; Stoop, Hans; Looijenga, Leendert H.; De Bosscher, Karolien; Cools, Martine; De Baere, Elfride; Atay, Zeynep; Bereket, Abdullah; de Krijger, Ronald R.; Preter, Katleen de; Domenice, Sorahia; Turan, SerapPublication Open Access Genotype of congenital adrenal hyperplasia patients with testicular adrenal rest tumor(2022-12-01) GÜRAN, TÜLAY; AYCAN Z., Keskin M., Lafci N. G. , Savas-Erdeve S., BAŞ F., POYRAZOĞLU Ş., Ozturk P., PARLAK M., Ercan O., GÜRAN T., et al.Testicular adrenal rest tumor (TART) is one of the important complications that can cause infertility in male patients with congenital adrenal hyperplasia (CAH) and should therefore be diagnosed and treated at an early age. The factors that result in TART in CAH have not been completely understood. The aim of this study is to evaluate the genotype-phenotype correlation in CAH patients with TART.Method: Among 230 malepatients with CAH who were followed upwith regular scrotal ultrasonography in 11 different centers in Turkey, 40 patients who developed TARTand whose CAH diagnosis was confirmed by genetic testing were included in this study. Different approaches and methods were used for genotype analysis in this multicenter study. A few centers first screened the patients for the ten most common mutations in CYP21A2 and performed Sanger sequencing for the remaining regions only if these prior results were inconclusive while the majority of the departments adopted Sanger sequencing for the whole coding regions and exon-intron boundaries as the primary molecular diagnostic approach for patients with either CYP21A2 orCYP11B1 deficiency. The age of CAH diagnosis and TART diagnosis, type of CAH, and identified mutations were recorded.Results: TART was detected in 17.4% of the cohort [24 patients with salt-wasting (SW) type, four simple virilizing type, and one with nonclassical type with 21-hydroxylase (CYP21A2) deficiency and 11 patients with 11-beta hydroxylase (CYP11B1) deficiency]. The youngest patients with TART presenting with CYP11B1 and CYP21A2 deficiency were of 2 and 4 years, respectively. Eight different pathogenic variants in CYP21A2were identified. The most common genotypes were c.293-13C>G/c.293-13C>G (31%) followed by c.955C>T/ c.955C>T(27.6%) and c.1069C>T/c.1069C>T (17.2%). Seven different pathogenic variants were identified in CYP11B1. The most common mutation in CYP11B1 in our study was c.896T>C (p.Leu299Pro).Conclusion: We found that 83% TART patients were affected with SW typeCYP21A2 deficiency,and the frequent mutations detected were c.955C>T (p.Gln319Ter), c.293-13C>G in CYP21A2 and c.896T>C (p.Leu299Pro) inCYP11B1. Patients with CYP11B1 deficiency may develop TART at an earlier age. This study that examined the genotype-phenotype correlation in TART may benefit further investigations in larger series.Publication Open Access A novel deletion involving the first GNAS exon encoding Gsα causes PHP1A without methylation changes at exon A/B(2022-04-01) BEREKET, ABDULLAH; DEMİRCİOĞLU, SERAP; GÜRAN, TÜLAY; Campbell D., Reyes M., Kaygusuz S. B., Abalı S., Güran T., Bereket A., Kagami M., Turan S., Jüppner H.© 2022Individuals affected by pseudohypoparathyroidism type 1A (PHP1A) display hyperphosphatemia and hypocalcemia despite elevated PTH levels, as well as features of Albright Hereditary Osteodystrophy (AHO). PHP1A is caused by variants involving the maternal GNAS exons 1–13 encoding the stimulatory G protein α-subunit (Gsα). MLPA and aCGH analysis led in a male PHP1A patient to identification of a de novo 1284-bp deletion involving GNAS exon 1. This novel variant overlaps with a previously identified 1438-bp deletion in another PHP1A patient (ref. Li et al. (2020) [13], patient 2) that extends from the exon 1 promoter into the up-stream intronic region. This latter deletion is associated with reduced methylation at GNAS exon A/B, i.e. the differentially methylated region (DMR) that is demethylated in most pseudohypoparathyroidism type 1B (PHP1B) patients. In contrast, genomic DNA from our patient revealed no evidence for an epigenetic GNAS defect as determined by MS-MLPA and pyrosequencing. These findings thus reduce the region, which, in addition to other nucleotide sequences telomeric of exon A/B, may undergo histone modifications or interacts with transcription factors and possibly as-yet unknown proteins that are required for establishing the maternal methylation imprints at this site. Taken together, nucleotide deletions or changes within an approximately 1300-bp region telomeric of exon A/B could be a cause of PHP1B variants with complete or incomplete loss-of-methylation at the exon A/B DMR. In addition, when investigating patients with suspected PHP1A, MLPA should be considered to search for structural abnormalities within this difficult to analyze genomic region comprising GNAS exon 1.Publication Open Access Homozygous Loss-of-function Mutations in SOHLH1 in Patients With Nonsyndromic Hypergonadotropic Hypogonadism(OXFORD UNIV PRESS INC, 2015-05) BEREKET, ABDULLAH; Bayram, Yavuz; Gulsuner, Suleyman; Guran, Tulay; Abaci, Ayhan; Yesil, Gozde; Gulsuner, Hilal Unal; Atay, Zeynep; Pierce, Sarah B.; Gambin, Tomasz; Lee, Ming; Turan, Serap; Bober, Ece; Atik, Mehmed M.; Walsh, Tom; Karaca, Ender; Pehlivan, Davut; Jhangiani, Shalini N.; Muzny, Donna; Bereket, Abdullah; Buyukgebiz, Atilla; Boerwinkle, Eric; Gibbs, Richard A.; King, Mary-Claire; Lupski, James R.Context: Hypergonadotropic hypogonadism presents in females with delayed or arrested puberty, primary or secondary amenorrhea due to gonadal dysfunction, and is further characterized by elevated gonadotropins and low sex steroids. Chromosomal aberrations and various specific gene defects can lead to hypergonadotropic hypogonadism. Responsible genes include those with roles in gonadal development or maintenance, sex steroid synthesis, or end-organ resistance to gonadotropins. Identification of novel causative genes in this disorder will contribute to our understanding of the regulation of human reproductive function. Objectives: The aim of this study was to identify and report the gene responsible for autosomal-recessive hypergonadotropic hypogonadism in two unrelated families. Design and Participants: Clinical evaluation and whole-exome sequencing were performed in two pairs of sisters with nonsyndromic hypergonadotropic hypogonadism from two unrelated families. Results: Exome sequencing analysis revealed two different truncating mutations in the same gene: SOHLH1 c.705delT (p.Pro235fs*4) and SOHLH1 c.27C>G (p.Tyr9stop). Both mutations were unique to the families and segregation was consistent with Mendelian expectations for an autosomal-recessive mode of inheritance. Conclusions: Sohlh1 was known from previous mouse studies to be a transcriptional regulator that functions in the maintenance and survival of primordial ovarian follicles, but loss-of-function mutations in human females have not been reported. Our results provide evidence that homozygous-truncating mutations in SOHLH1 cause female nonsyndromic hypergonadotropic hypogonadism.Publication Open Access Real-World Estimates of Adrenal Insufficiency-Related Adverse Events in Children With Congenital Adrenal Hyperplasia(ENDOCRINE SOC, 2021-01-01) GÜRAN, TÜLAY; Ali, Salma R.; Bryce, Jillian; Haghpanahan, Houra; Lewsey, James D.; Tan, Li En; Atapattu, Navoda; Birkebaek, Niels H.; Blankenstein, Oliver; Neumann, Uta; Balsamo, Antonio; Ortolano, Rita; Bonfig, Walter; Claahsen-van der Grinten, Hedi L.; Cools, Martine; Costa, Eduardo Correa; Darendeliler, Feyza; Poyrazoglu, Sukran; Elsedfy, Heba; Finken, Martijn J. J.; Fluck, Christa E.; Gevers, Evelien; Korbonits, Marta; Guaragna-Filho, Guilherme; Guran, Tulay; Guven, Ayla; Hannema, Sabine E.; Higham, Claire; Hughes, Ieuan A.; Tadokoro-Cuccaro, Rieko; Thankamony, Ajay; Iotova, Violeta; Krone, Nils P.; Krone, Ruth; Lichiardopol, Corina; Luczay, Andrea; Mendonca, Berenice B.; Bachega, Tania A. S. S.; Miranda, Mirela C.; Milenkovic, Tatjana; Mohnike, Klaus; Nordenstrom, Anna; Einaudi, Silvia; van der Kamp, Hetty; Vieites, Ana; de Vries, Liat; Ross, Richard J. M.; Ahmed, S. FaisalBackground: Although congenital adrenal hyperplasia (CAH) is known to be associated with adrenal crises (AC), its association with patient- or clinician-reported sick day episodes (SDE) is less clear. Methods: Data on children with classic 21-hydroxylase deficiency CAH from 34 centers in 18 countries, of which 7 were Low or Middle Income Countries (LMIC) and 11 were High Income (HIC), were collected from the International CAH Registry and analyzed to examine the clinical factors associated with SDE and AC. Results: A total of 518 children-with a median of 11 children (range 1, 53) per center-had 5388 visits evaluated over a total of 2300 patient-years. The median number of AC and SDE per patient-year per center was 0 (0, 3) and 0.4 (0.0, 13.3), respectively. Of the 1544 SDE, an AC was reported in 62 (4%), with no fatalities. Infectious illness was the most frequent precipitating event, reported in 1105 (72%) and 29 (47%) of SDE and AC, respectively. On comparing cases from LMIC and HIC, the median SDE per patient-year was 0.75 (0, 13.3) vs 0.11 (0, 12.0) (P < 0.001), respectively, and the median AC per patient-year was 0 (0, 2.2) vs 0 (0, 3.0) (P = 0.43), respectively. Conclusions: The real-world data that are collected within the I-CAH Registry show wide variability in the reported occurrence of adrenal insufficiency-related adverse events. As these data become increasingly used as a clinical benchmark in CAH care, there is a need for further research to improve and standardize the definition of SDE.Publication Open Access IRS2 variants and syndromes of severe insulin resistance(SPRINGER, 2009-06) GÜRAN, TÜLAY; Bottomley, W. E.; Soos, M. A.; Adams, C.; Guran, T.; Howlett, T. A.; Mackie, A.; Miell, J.; Monson, J. P.; Temple, R.; Tenenbaum-Rakover, Y.; Tymms, J.; Savage, D. B.; Semple, R. K.; O'Rahilly, S.; Barroso, I.