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Öğe Clinical and Molecular Findings in a Turkish Family Who Had a (c.869-1G>A) Splicing Variant in PSEN1 Gene with A Rare Condition: The Variant Alzheimer's Disease with Spastic Paraparesis(Bentham Science Publ Ltd, 2022) Dogan, Mustafa; Eroz, Recep; Tecellioglu, Mehmet; Gezdirici, Alper; Cevik, Betul; Baris, IbrahimBackground: Early-onset Alzheimer's disease (EOAD) is commonly diagnosed with an onset age of earlier than 65 years and accounts for 5-10% of all Alzheimer's disease (AD) cases. To date, although only 10-15% of familial EOAD cases have been explained, the genetic cause of the vast proportion of cases has not been explained. The variant Alzheimer's disease with spastic paraparesis (varAD) is defined as a rare clinical entity characterized by early-onset dementia, spasticity of the lower extremities, and gait disturbance. Although the disease was first associated with variants in exon 9 of the PSEN1 gene, it was later shown that variations in other exons were also responsible for the disease. Objective: The current study aims to raise awareness of varAD, which occurs as a rare phenotype due to pathogenic variants in PSEN1. In addition, we aimed to evaluate the spectrum of mutations in varAD patients identified to date. Methods: Detailed family histories and clinical data were recorded. Whole exome sequencing was performed and co-segregation analysis of the family was done by Sanger sequencing. Also, a review of the molecularly confirmed patients with (varAD) from the literature was evaluated. Results: We identified a heterozygous splicing variant (c.869-1G>A) in the PSEN1 gene, in a family with two affected individuals who present with varAD. We reported the clinical and genetic findings from the affected individuals. Conclusion: We present the detailed clinical and genetic profiles of a Turkish patient with the diagnosis of varAD together with subjects from the literature. Together, we think that the clinical characteristics and the effect of the (c.869-1G>A) variant will facilitate our understanding of the PSEN1 gene in AD pathogenesis.Öğe High prevalence of multilocus pathogenic variation in neurodevelopmental disorders in the Turkish population(Cell Press, 2021) Mitani, Tadahiro; Isikay, Sedat; Gezdirici, Alper; Gulec, Elif Yilmaz; Punetha, Jaya; Fatih, Jawid M.; Herman, IsabellaNeurodevelopmental disorders (NDD5) are clinically and genetically heterogenous; many such disorders are secondary to perturbation in brain development and/or function. The prevalence of NDD5 is > 3%, resulting in significant sociocultural and economic challenges to society. With recent advances in family-based genomics, rare-variant analyses, and further exploration of the Clan Genomics hypothesis, there has been a logarithmic explosion in neurogenetic disease-associated genes molecular etiology and biology of NDD5; however, the majority of NDD5 remain molecularly undiagnosed. We applied genome-wide screening technologies, including exome sequencing (ES) and whole-genome sequencing (WGS), to identify the molecular etiology of 234 newly enrolled subjects and 20 previously unsolved Turkish NDD families. In 176 of the 234 studied families (75.2%), a plausible and genetically parsimonious molecular etiology was identified. Out of 176 solved families, deleterious variants were identified in 218 distinct genes, further documenting the enormous genetic heterogeneity and diverse perturbations in human biology underlying NDD5. We propose 86 candidate disease-trait-associated genes for an NDD phenotype. Importantly, on the basis of objective and internally established variant prioritization criteria, we identified 51 families (51/176 = 28.9%) with multilocus pathogenic variation (MPV), mostly driven by runs of homozygosity (ROH5) - reflecting genomic segments/haplotypes that are identical-by-descent. Furthermore, with the use of additional bioinformatic tools and expansion of ES to additional family members, we established a molecular diagnosis in 5 out of 20 families (25%) who remained undiagnosed in our previously studied NDD cohort emanating from Turkey.Öğe Hypohidrotic Ectodermal Dysplasias: Phenotypic and Genotypic Findings in 32 Cases(Wiley, 2026) Esener, Zeynep; Yuecesoy, Mehmet Akif; Gezdirici, Alper; Dogan, Mustafa; Turkyilmaz, Ayberk; Tekedereli, Ibrahim; Bas, HasanHypohidrotic ectodermal dysplasias are a genetic condition affecting ectoderm-derived structures such as hair, teeth, nails, and sweat glands, resulting from variations in the EDA, EDAR, EDARADD, and WNT10A genes. This study examined 32 cases from 25 unrelated families from T & uuml;rkiye, identifying seven novel variants in the EDA, EDAR, and WNT10A genes. The distribution of genetic alterations across the cohort revealed that 44% of the families (11/25) harbored variants in EDA, whereas EDAR and WNT10A variants were identified in 32% (8/25) and 24% (6/25) of families, respectively. Clinical evaluation revealed the characteristic hypohidrotic ectodermal dysplasia triad of hypotrichosis, hypodontia, and hypohidrosis was observed in 87.5% of cases, along with other symptoms such as dry skin, atopic dermatitis, and developmental delays. All cases presented with hair, eyebrow, and eyelash abnormalities, ranging in severity from subtle thinning to marked hypotrichosis. Among the cohort, one case exhibited severe atopic dermatitis as the predominant symptom. Targeted next-generation sequencing and clinical exome sequencing were employed to determine the genetic basis of the condition, emphasizing the importance of early diagnosis for targeted interventions. This study expands the genetic and phenotypic spectrum of hypohidrotic ectodermal dysplasia, presenting a comprehensive overview of molecular findings and genotype-phenotype correlations in the population from the Turkish population.Öğe An integrated clinical and molecular study of a cohort of Turkish patients with Marfan syndrome harboring known and novel FBN1 variants(Springernature, 2021) Gezdirici, Alper; Terali, Kerem; Gulec, Elif Yilmaz; Bornaun, Helen; Dogan, Mustafa; Eroz, RecepMarfan syndrome (MFS) is an autosomal dominant genetic condition that mainly affects connective tissue in many parts of the body. Cardinal manifestations involve the ocular, skeletal, and cardiovascular systems. The diagnosis of MFS relies on the revised Ghent criteria, outlined by international expert opinion to facilitate accurate recognition of this syndrome as well as to improve patient management and counseling. However, it may not always be possible to make a definitive diagnosis according to these criteria in each patient and thus molecular confirmation is necessary in subjects with suspected MFS. This debilitating, if not fatal, disorder is caused by mutations in FBN1, which encodes a major constitutive element of extracellular microfibrils. Here, we present a detailed clinical and molecular analysis of 76 Turkish patients with definitive or suspected MFS diagnosed at our center between 2014 and 2019. We were able to identify a total of 51 different FBN1 variants in our cohort, 31 of which have previously been reported in the relevant scientific literature. The remaining 20 variants have not been documented to date. In one patient, we detected a large deletion including the entire FBN1 gene using the array CGH approach. Currently, there are very few studies on the genotype-phenotype correlation of patients with MFS, and no clear genotype-phenotype maps for MFS have been constructed so far, except for some cases. We believe that our findings will make a rich and peculiar contribution to the elusive genotype-phenotype relationship in MFS, especially in this large and populous ethnic group.Öğe Molecular and Clinical Profiles of Patients with RASopathies: Targeted Next-Generation Sequencing Panel Results and Identification of 14 Novel Disease-Causing Variants(Karger, 2025) Ates, Kubra; Ozturk, Murat; Esener, Zeynep; Dogan, Mustafa; Gezdirici, Alper; Sarac, Hatice; Yeninarcilar, BusraIntroduction: RASopathies are among the most prevalent genetic syndromes caused by variants in the Ras/MAPK signaling pathway, affecting various systems such as the heart, craniofacial features, skin, musculoskeletal system, hearing, and vision. They can also increase the risk of secondary malignancies. Despite clinical overlaps, distinguishing features are crucial for diagnosis, as different variants lead to distinct clinical implications. This study reviews the molecular and clinical characteristics of RASopathies, focusing on neurofibromatosis type 1 (NF1) and non-NF1 RASopathies. Methods: The study analyzed 76 patients referred to our outpatient clinic over a 6-year period, all of whom were clinically diagnosed with RASopathy and confirmed in most cases by molecular testing. Patient files, clinical photographs, and laboratory results were reviewed and analyzed. A targeted multigene next-generation sequencing panel test was performed, followed by Sanger sequencing for both confirmation and segregation analysis. Multiplex ligation-dependent probe amplification was conducted in a patient with normal sequence results but strong clinical suspicion, to identify potential deletions. Results: We identified 44 pathogenic, 25 likely pathogenic variants, and 6 variants of uncertain significance based on American College of Medical Genetics and Genomics (ACMG) criteria. Among these, 14 novel variants were found - 13 in the NF1 gene and one in SOS1. NF1 variants were present in 51 cases. Additional variants, likely to represent clinically significant findings, were identified in PTPN11 (n = 11), RAF1 (n = 4), SOS1 (n = 3), RIT1 (n = 3), KRAS (n = 1), NRAS (n = 1), SOS2 (n = 1), and BRAF (n = 1). Diagnoses included 49 patients with NF1, 21 with Noonan syndrome, 2 with neurofibromatosis-Noonan syndrome, 2 with Noonan syndrome with multiple lentigines, and 1 with cardiofaciocutaneous syndrome. Here, 12% of NF1 variants were located in exon 21, 36% of PTPN11 variants in exon 3, and 75% of RAF1 variants in exon 7. Conclusion: RASopathies have a broad molecular and clinical spectrum, complicating diagnosis and management. Accurate clinical correlation and molecular analysis are essential, as different RASopathy syndromes can result from variants in the same genes, while the same syndrome may arise from different genetic alterations. This study identifies novel variants and emphasizes the need for precise diagnostic approaches in these complex disorders.
