Browsing by Author "Demirbilek, Hüseyin"

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    Clinical characteristics of patients presented with primary adrenal insufficiency due to a p.R451W mutation in the CYP11A1 gene
    (Karger, 2023) Çayır, Atilla; Özbek, Mehmet Nuri; Demirbilek, Hüseyin; Özbek, Mehmet Nuri; Kurt, İlknur; Karaoğlan, Murat; Albayrak, Serpil; Dündar, Bumin Nuri; Güran, Tülay; Department of Internal Medical Sciences / Dahili Tıp Bilimleri Bölümü; 10. Faculty of Medicine / Tıp Fakültesi; 01. Mardin Artuklu University / Mardin Artuklu Üniversitesi
    Background and objective: The first and rate-limiting step of steroidogenesis is the conversion of cholesterol to pregnanolone which is catalyzed by the P450scc side chain cleavage enzyme (encoded by CYP11A1 gene-SCC). Homozygous recessive mutations of the CYP11A1 gene cause a global steroid hormone deficiency thereby disorders of sexual development in 46, XY individuals with a variable phenotype depending on the mutation characteristics. About 60 cases of SCC deficiency due to CYP11A1 gene mutation have been reported so far. The most common mutation is the c.1351C>T (p.R451W) mutation, which has been detected in 12 cases. We, herein, present the clinical characteristics of 14 cases presented with adrenal insufficiency due to p.R451W mutation in the CYP 11A1 gene. Design and method: Data were retrospectively collected from tertiary pediatric endocrine centers using a standardized proforma. Family history, presenting age, clinical, biochemical, and hormonal characteristics, treatment options, and the follow-up characteristics obtained during their latest follow-up visits were recorded. Results: 14 patients (M/F:7/7) from 10 consanguineous Turkish families were recruited. The mean age of the diagnosis was 3.8±2.4(Range: 1.04-8.5 years). All of the male subjects were completely virilized with no sign of DSD. The main presenting complaints were signs and symptoms of primary adrenal insufficiency. However, despite having signs and symptoms 3 subjects were diagnosed when investigated due to the history of their affected siblings. While glucocorticoid deficiency (elevated ACTH, low cortisol) was present in all cases, none of the male cases had undervirilization excluding androgen deficiency. Mild mineralocorticoid (MC) deficiency was detected in 10/14 of the cases which were recovered in 2 subjects during follow-up. More strikingly, one patient with no MC deficiency at presentation had developed a salt-wasting adrenal crisis during acute illness. Although a deterioration was detected in height SDS, there was not a statistically significant difference between height SDS at presentation (-0.64±1.4), at the latest follow-up visit(-0.90±1.4), and target height SDS (-0.63±0.6). Conclusion: In the present largest case series with a p.R451W mutation in the CYP11A1 gene our results confirmed a milder phenotype for all steroid hormones. Particularly lack of virilization defect in male subjects, and lack of salt-wasting crisis until a relatively late age of diagnosis suggested mild MC and androgen deficiency. Nevertheless, lack of MC deficiency at presentation does not exclude the risk of developing a salt-wasting adrenal crisis. Therefore special caution requires for patients with no MC replacement, particularly during acute illnesses.
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    Article
    Genotype, Phenotype Characteristics and Long-Term Follow-Up of Patients with Vitamin D-Dependent Rickets Type IA: A Nationwide Multi-Centre Retrospective Cross-Sectional Study
    (S. Karger AG, 2025) Çayir, Atilla; Demirbilek, Hüseyin; Türkyılmaz, Ayberk; Turan, Serap Demircioğlu; Bereket, Abdullah; Darendeli̇Ler, Feyza F.; Ökdemir, Deniz
    Introduction: Vitamin D-dependent rickets type IA (VDDR1A) is an autosomal recessive disorder characterized by defects in the biosynthesis of its active form 1,25-dihydroxyvitamin D due to mutations in the CYP27B1 gene, which encodes for 1α- hydroxylase. The present study aimed to evaluate the clinical characteristics, molecular genetic aetiology, and long-term outcomes of a large nationwide cohort of children with VDDR1A from Turkey. Methods: In this multi-centre retrospective cross-sectional study, we collected clinical characteristics, laboratory features, molecular genetic analysis results, and long-term follow-up of a nationwide cohort of patients with VDDR1A using a web-based research network, CEDD-NET, for paediatric endocrinology research. Results: In total, 118 patients (57 F, 61 M) with VDDR1A were recruited. The median age of the diagnosis was 1.7 years (0.2-18.3 years). The most common presenting complaints were skeletal deformity (n = 61), short stature (n = 45), and delay in walking (n = 42). The most common mutation was a splice-donor-site mutation (c.195+2T>G) (n = 42), followed by a 7-bp duplication 1319-1325dupCCCACCC (Phe443Profs∗24) (n = 25), and two missense mutations p.K192E (c.574A>G) (n = 17) and c.1474C>T (p.R492W) (n = 12). The novel c.195+2T>C and c.1215_1215+2delTGTinsCGA splice-site and c.1144C>A missense variants were firstly described in our cohort. Conclusion: The most common four mutations accounted for the underlying aetiology of VDDR1A in approximately 81% of the cohort, indicating Turkey may serve as a mutational hotspot or exhibit a founder effect for these variants. Our large cohort s results suggested no clear and clinically meaningful phenotype-genotype relationship in VDDR1A. © 2025 Elsevier B.V., All rights reserved.