Ahmet Uçar

Ahmet Uçar

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Ahmet Uçar

Division of Pediatric Endocrinology , Şişli Hamidiye Etfal Training and Research Hospital, University of Health Sciences , Istanbul , Türkiye

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2016 in The Journal of Clinical Endocrinology & Metabolism
Verified
Journal Article
Open access
PDF file
TGTulay Guran
Tulay Guran
FBFederica Buonocore
Federica Buonocore
NSNurcin Saka
Nurcin Saka
MOMehmet Nuri Ozbek
Mehmet Nuri Ozbek
ZAZehra Aycan
Zehra Aycan
JAJohn C. Achermann
John C. Achermann
Context: Primary adrenal insufficiency (PAI) is a life-threatening condition that is often due to monogenic causes in children. Although congenital adrenal hyperplasia occurs commonly, several other important molecular causes have been reported, often with overlapping clinical and biochemical features. The relative prevalence of these conditions is not known, but making a specific diagnosis can have important implications for management. Objective: The objective of the study was to investigate the clinical and molecular genetic characteristics of a nationwide cohort of children with PAI of unknown etiology. Design: A structured questionnaire was used to evaluate clinical, biochemical, and imaging data. Genetic analysis was performed using Haloplex capture and next-generation sequencing. Patients with congenital adrenal hyperplasia, adrenoleukodystrophy, autoimmune adrenal insufficiency, or obvious syndromic PAI were excluded. Setting: The study was conducted in 19 tertiary pediatric endocrinology clinics. Patients: Ninety-five children (48 females, aged 0–18 y, eight familial) with PAI of unknown etiology participated in the study. Results: A genetic diagnosis was obtained in 77 patients (81%). The range of etiologies was as follows: MC2R (n = 25), NR0B1 (n = 12), STAR (n = 11), CYP11A1 (n = 9), MRAP (n = 9), NNT (n = 7), ABCD1 (n = 2), NR5A1 (n = 1), and AAAS (n = 1). Recurrent mutations occurred in several genes, such as c.560delT in MC2R, p.R451W in CYP11A1, and c.IVS3ds+1delG in MRAP. Several important clinical and molecular insights emerged. Conclusion: This is the largest nationwide study of the molecular genetics of childhood PAI undertaken. Achieving a molecular diagnosis in more than 80% of children has important translational impact for counseling families, presymptomatic diagnosis, personalized treatment (eg, mineralocorticoid replacement), predicting comorbidities (eg, neurological, puberty/fertility), and targeting clinical genetic testing in the future.

21 November 2018 in BioMed Research International
Verified
Journal Article
Open access
PDF file
JLJiwon M. Lee
Jiwon M. Lee
JSJaewon Shin
Jaewon Shin
SKSol Kim
Sol Kim
HGHeon Yung Gee
Heon Yung Gee
JLJoon Suk Lee
Joon Suk Lee
Jae Il ShinJae Il Shin
Jae Il Shin
Background and Aim. ROHHADNET (rapid-onset obesity with hypoventilation, hypothalamic, autonomic dysregulation, neuroendocrine tumor) syndrome is a rare disease with grave outcome. Although early recognition is essential, prompt diagnosis may be challenging due to its extreme rarity. This study aimed to systematically review its clinical manifestation and to identify genetic causes. Materials and Methods. We firstly conducted a systematic review on ROHHAD/NET. Electronic databases were searched using related terms. We secondly performed whole exome sequencing (WES) and examined copy number variation (CNV) in two patients to identify genetic causes. Results. In total, 46 eligible studies including 158 patients were included. There were 36 case reports available for individual patient data (IPD; 48 patients, 23 ROHHAD, and 25 ROHHADNET) and 10 case series available for aggregate patient data (APD; 110 patients, 71 ROHHAD, and 39 ROHHADNET). The median age at onset calculated from IPD was 4 years. Gender information was available in 100 patients (40 from IPD and 60 from APD) in which 65 females and 35 males were showing female preponderance. Earliest manifestation was rapid obesity, followed by hypothalamic symptoms. Most common types of neuroendocrine tumors were ganglioneuromas. Patients frequently had dysnatremia and hyperprolactinemia. Two patients were available for WES. Rare variants were identified in PIK3R3, SPTBN5, and PCF11 in one patient and SRMS, ZNF83, and KMT2B in another patient, respectively. However, there was no surviving variant shared by the two patients after filtering. Conclusions. This study systematically reviewed the phenotype of ROHHAD/NET aiming to help early recognition and reducing morbidity. The link of variants identified in the present WES requires further investigation.

1 September 2016 in Journal of Clinical Research in Pediatric Endocrinology
Verified
Journal Article
Open access
AYAylin Yetim-Sahin
Aylin Yetim-Sahin
ÇYÇağcıl Yetim
Çağcıl Yetim
FBFirdevs Baş
Firdevs Baş
OEOğuz Bülent Erol
Oğuz Bülent Erol
GÇGülnaz Çığ
Gülnaz Çığ
FDFeyza Darendeliler
Feyza Darendeliler
Polycystic ovary syndrome (PCOS) is a common endocrine problem in adolescents with an increasing prevalence of 30%. Pursuing new biomarkers with high specificity and sensitivity in the diagnosis of PCOS in adolescents is currently an active area of research. We aimed to investigate the diagnostic value of anti-Müllerian hormone (AMH), insulin-like peptide-3 (INSL3), inhibin-A (INH-A), and inhibin-B (INH-B) in adolescents with PCOS and also to determine the association, if any, between these hormones and clinical/laboratory findings related with hyperandrogenism. The study group comprised 53 adolescent girls aged between 14.5 and 20 years who were admitted to our outpatient clinic with symptoms of hirsutism and/or irregular menses and diagnosed as having PCOS in accordance with the Rotterdam criteria. Twenty-six healthy peers, eumenorrheic for at least two years and body mass index-matched, constituted the controls. Fasting blood samples for hormones [luteinizing hormone (LH), follicle-stimulating hormone (FSH), dehydroepiandrosterone-sulfate (DHEAS), androstenedione (D4-A), total/free testosterone (T/fT), sex hormone binding globulin (SHBG), AMH, INSL3, INH-A, INH-B] were drawn after an overnight fast. In the PCOS group, 83% of the subjects were oligomenorrheic/amenorrheic and 87% had hirsutism. The LH, LH/FSH ratio, total T, fT, free androgen-index (FAI), DHEAS levels were significantly higher (p=0.005, p=0.042, p=0.047, p0.05), AMH and INH-A levels were found to be significantly higher in the PCOS group compared to the controls (p<0.001, p<0.001, respectively). In multiple linear regression analysis, WC SDS (p=0.028), logD4-A (p=0.033), logSHBG (p=0.031), and total ovarian volume (p=0.045) had significant effects on AMH levels, and LH (p=0.003) on INH-A levels. In receiver-operating characteristic analysis, the cut-off values for AMH and INH-A were 6.1 ng/mL (sensitivity 81.1%) and 12.8 pg/mL (sensitivity 86.8%), respectively, to diagnose PCOS. When AMH and INH-A were used in combination, the sensitivity (96.2%) increased. INSL3 and INH-B were not found to have diagnostic value in adolescents with PCOS. On the other hand, it was shown that INH-A could be used as a new diagnostic biomarker in addition to AMH.

8 April 2016 in World Journal of Pediatrics
Verified
Journal Article
Closed access
PDF file
AUAhmet Uçar
Ahmet Uçar
FBFirdevs Baş
Firdevs Baş
NSNurçin Saka
Nurçin Saka

5 March 2013 in Journal of Clinical Research in Pediatric Endocrinology
Verified
Journal Article
Open access
CPCengiz Pınar
Cengiz Pınar
BFBaş Firdevs
Baş Firdevs
FAFatmahan Atalar
Fatmahan Atalar
UAUçar Ahmet
Uçar Ahmet
DFDarendeliler Feyza
Darendeliler Feyza
TTTarhan Tuğba
Tarhan Tuğba
Idiopathic short stature (ISS) is a heterogeneous disorder. An impairment of growth hormone (GH)/insulin-like growth factor 1 (IGF-1)/IGF-1 receptor (IGF-1 R) axis is postulated. To evaluate the somatotropic axis in relation to body mass index (BMI), serum IGF-1, IGF-binding protein-3 (IGFBP-3) and the expression of IGF-1 R genes in patients with ISS. Fifty-five ISS patients (24 F/31 M) aged 14.6 ± 5.5 years (range 3.5-28.5 years) and 25 BMI- and pubertal stage-matched peers were enrolled in the study. The ISS patients underwent a four-day standard GH stimulation test to evaluate IGF-1 generation. mRNA expression of the IGF-1 R gene in peripheral blood leukocytes was evaluated. ISS patients and controls were compared with respect to anthropometric and laboratory data. The results were also analyzed after subdividing the two groups into low-normal [BMI standard deviation score (SDS) between -2 to -1)] and normal (BMI SDS between -1 to +1) BMI subgroups. Basal serum IGF-1 concentrations were lower in ISS subjects compared to controls who had similar BMI SDS values (p=0.000). Subgroup analyses revealed that there were no significant differences between low-normal BMI ISS subjects and low-normal BMI controls with respect to serum IGF-1 and IGFBP-3 concentrations. However, in the normal BMI ISS subgroup, basal and stimulated IGF-1 levels were significantly lower than the basal values in their control counterparts (basal: p=0.000; stimulated: p=0.007). mRNA expression of IGF-1 R gene was not found to be significantly different in ISS subjects and controls. ISS patients were found to have lower IGF-1 concentrations than BMI-matched peers, a finding supporting presence of an impairment in the somatotropic axis. IGF-1 R expression does not seem to be impaired in ISS patients. ISS patients with low-normal BMI SDS also tend to display a relative IGF-1 resistance, whereas those with normal BMI SDS tend to be less GH-sensitive than healthy peers.

1 January 2013 in Journal of Pediatric Endocrinology and Metabolism
Verified
Journal Article
Closed access
AUAhmet Uçar
Ahmet Uçar
NSNurçin Saka
Nurçin Saka
FBFirdevs Baş
Firdevs Baş
MSMine Sukur
Mine Sukur
SPSukran Poyrazoğlu
Sukran Poyrazoğlu
RBRuveyde Bundak
Ruveyde Bundak
To assess the frequency and severity of diabetic ketoacidosis (DKA) at disease onset in children newly diagnosed with autoimmune type 1 diabetes (T1D) in Istanbul in the last decade. Also, to evaluate the potential contribution of the national diabetes awareness programme (NDAP) initiated in 2010. Four hundred and one consecutive children (mean ± standard deviation, age 8.1 ± 4.1 years) with a diagnosis of autoimmune T1D were evaluated retrospectively with respect to demographic, clinical, and laboratory data in relation to DKA at disease onset. The possible impact of NDAP on the rate of DKA at disease onset in the last 2 years was also evaluated by comparing the data related to the time intervals before and after the onset of the programme. The results were evaluated at 95% confidence interval and significance was granted for p ≤ 0.05. The overall frequency of DKA at disease onset was 44.2%, with a significant trend for decline in rate of DKA at disease onset in the last decade (p=0.0001). There were no significant differences in proportions of newly diagnosed T1D patients with severe or moderate DKA over time. Mean body mass index standard deviation score tended to increase in the last decade, but not significantly (p=0.09). When the time intervals before and after the onset of NDAP were evaluated, there was a more than two-fold decrease in rate of DKA (from 49.3% to 23.9%) (p<0.0001). The frequency of a DKA event at onset of T1D is still high in Istanbul children despite a decreasing trend in the last decade. NDAP may significantly contribute to the reduction in rate of DKA.