Investigation of genotype-phenotype and familial features of Turkish dystrophinopathy patients.

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are X-linked recessive allelic muscle diseases caused by dystrophin gene mutations. Eight hundred thirty-seven patients admitted between 1997 and 2022 were included in the study. Two hundred twenty patients were analyzed by multiplex PCR (mPCR) alone. Five hundred ninety-five patients were investigated by multiplex ligation-dependent probe amplification (MLPA), and 54 patients were examined by sequencing. Deletion was detected in 60% (132/220) of the cases in the mPCR group only and in 58.3% (347/595) of the cases with MLPA analysis. The rates of deletion and duplication were 87.7% and 12.3%, respectively, in the MLPA analysis. Single exon deletions were the most common mutation type. The introns 43-55 (81.8%) and exons 2-21 (13.1%) regions were detected as hot spots in deletions. It was determined that 89% of the mutations were suitable for exon skipping therapy. The reading frame rule did not hold in 7.6% of D/BMD cases (17/224). We detected twenty-five pathogenic/likely pathogenic variants in sequencing, five of which were novel variants. Nonsense mutation was the most common small mutation (44%). 21% of DMD patients were familial. We detected germline mosaicism in four families (4.3%) in the large rearrangement group and one gonosomal mosaicism in a family with a nonsense mutation. This is the largest study examining genotype and phenotype data in Turkish D/BMD families investigated by MLPA analysis. The reading frame hypothesis is not valid in all cases. Sharing the genotype and phenotype characteristics of these cases in the literature will shed light on the molecular structure of DMD and guide gene therapy research. In genetic counseling, carrier screening in the family and possible gonadal mosaicism should be emphasized.

Molecular Diagnosis of Limb-Girdle Muscular Dystrophy Using Next-Generation Sequencing Panels.

Introduction: Limb-girdle muscular dystrophies (LGMDs) are clinically and genetically heterogeneous muscle disorders. We aimed to share the diagnostic yield of an NGS gene panel containing LGMD-related genes and our experience with LGMD. Methods: Between February 2019 and October 2022, patients with a suspicion of LGMD and their relatives were reviewed in terms of demographic, clinical, and individual genetic data, age of symptom onset, sex, clinical features, LGMD types, cardiac involvement, muscle biopsy results, family history, and consanguinity. Our NGS gene panel consisted of ANO5, CAPN3, CAV3, DAG1, DES, DNAJB6, DYSF, FKTN, FLNC, FRKP, GAA, GMPPB, HNRNPDL, ISPD, LIMS2, LMNA, MYOT, PLEC, POMGNT1, POMK, POMT1, POMT2, SGCA, SGCB, SGCD, SGCG, TCAP, TNPO3, TRAPPC11, TRIM32, and TTN genes. Results: The diagnosis rate was 61.1% (11/18). Twelve (80%) patients with LGMD were male and three (20%) were female. The median age was 15.9 (range, 1.5-39) years. Our patient collective was drawn up out of patients with the following variants: LGMDR1 (n = 6; 40%), LGMDR2 (n = 4; 26.6%), LGMDR3 (n = 4; 26.6%), and LGMDR12 (n = 1; 6.7%). Conclusion: The present study showed that the NGS panel has a high success rate in the diagnosis of LGMD and contributes to early diagnosis.

Clinical Heterogeneity in Patients with Long QT Syndrome and Segregation of Single Nucleotide Variants and Clinical Symptoms in 17 Affected Families.

Introduction: Long QT syndrome (LQTS) is a disorder of ventricular myocardial repolarization characterized by a prolonged QT interval on the electrocardiogram. It increases the risk of ventricular arrhythmias, which can cause syncope or sudden cardiac death. In this study, we study the genotype-phenotype relationships of patients referred to us with suspected arrhythmia syndrome. Methods: Seventeen cases and their twenty relatives were evaluated. Next-generation sequencing analysis was performed for 17 LQTS-related genes. Results: We detected seventeen single nucleotide variants (SNVs) with potential pathogenic significance in 26 of the 36 subjects analyzed. KCNH2 c.172G>A, KCNQ1 c.1768G>A, ANK2 c.4666A>T, c.1484_1485delCT, KCNH2 c.1888G>A were reported as pathogenic or likely pathogenic in HGMD variant classification database. Conclusion: Current study pointed out that early diagnosis can be life-saving for patients and their families by taking family history and detailed examination. Also, we highlight the clinical heterogeneity of arrhythmia syndrome through a patient with a dual phenotype.

Genetic evaluation of 50 Turkish patients with neurofibromatosis type 1: 2 years experience of a single center.

BACKGROUND/AIM: Neurofibromatosis type 1 is an autosomal dominant neurocutaneous disorder. Clinical diagnosis is difficult in early childhood, and it is possible to miss a critical interval for tumour screening. In this study, we aimed to characterize the mutational spectrum of Turkish patients and discuss the benefits of molecular testing. MATERIAL AND METHODS: Fifty individuals from 35 unrelated families were included. Main referral reasons for genetic testing were as follows: to confirm a clinical diagnosis, to use in differential diagnosis and to evaluate first-degree family member of a known patient. Two-step process consisting of initial next generation sequencing of the NF1 gene and consequent multiplex ligation-dependent probe amplification were performed. RESULTS: We identified a total of 30 variants in 28 individuals. Variant detection rate was 56% in the entire study group and 71.4% within the index patients. Four novel variants were found. Truncating variants constituted 60% of the entire mutation spectrum. A deletion or duplication was not detected. The most common feature was cafe au lait macules in 70% of the patients, followed by focal areas of signal intensity on brain imaging (26%), cutaneous neurofibromas (24%) and axillary freckling (24%). CONCLUSIONS: Early sequencing in all suspected patients followed by deletion/duplication analysis in patients meeting clinical criteria and a case-to-case based consideration for RNA studies seems to be the effective algorithm for NF-1 diagnosis.

Investigation of different genomic variants in familial Mediterranean fever cases with monoallelic MEFV mutation.

OBJECTIVES: Familial Mediterranean Fever (FMF) is an inflammatory disease characterised by periodic fever and concurrent episodes of serous membrane inflammation. FMF is considered to be inherited in autosomal recessive manner and biallelic mutations in the MEFV gene are associated with the disease. However, approximately 20-25% of patients only have a single mutation in MEFV gene, which creates confusion in differential diagnosis of many patients. This study aimed to reveal rare variants that may act in conjunction with the single pathogenic MEFV variant in the pathogenesis of FMF. METHODS: We performed whole exome sequencing in 17 individuals from 5 different families who were diagnosed according to the clinical criteria, responded positively to colchicine treatment, but had no biallelic MEFV mutation. RESULTS: A disease-causing variant or a common affected cellular pathway that was shared in all index cases was not detected. When cases were examined individually, two de novo variants were identified in the BIRC2 and BCL10 genes, both of which play a role in inflammatory pathways. Functional studies are needed to confirm the physiopathological relationship of these genes with FMF. CONCLUSIONS: This study is one of the most extensive aetiological researches in FMF cases with monoallelic MEFV mutation. We have shown that genotype-phenotype correlation in these cases may not be established by rare genetic variants and discussed underlying causes. Clinical criteria with emphasis on colchicine response and family history should be the main tool and genetic results should only be used for support in FMF diagnosis.

Spondyloepimetaphyseal dysplasia-Maroteaux type due to dominant TRPV4 mutation: expanding the phenotype with a case report.

INTRODUCTION: Dominant pathogenic mutations in the TRPV4 gene give rise to a wide spectrum of abnormal phenotypes, including bone dysplasia as well as spinal muscular atrophy and hereditary motor and sensory neuropathy. Spondyloepimetaphyseal dysplasias (SEMDs) are autosomal dominant skeletal dysplasias characterized by mild epiphyseal dysplasia, flared metaphyses, prominent joints, spondyler dysplasia, and brachydactyly with various carpal, metacarpal, and finger malformations. CASE PRESENTATION: We present a boy who has the clinical and radiological signs of SEMD-M with a dominant TRPV4 mutation. He also has some striking findings that have not been seen in these patients before, and they may be able to provide assistance to medical professionals in the process of diagnosis.These include a shorter distance between his lumbar vertebrae, congenital contractures, and an arachnoid cyst.

Evaluation of hereditary/familial breast cancer patients with multigene targeted next generation sequencing panel and MLPA analysis in Turkey.

Breast cancer, a worldwide leading cause of cancer in women, may occur in familial cases. Germline mutations in BRCA1/2 genes are responsible for 15% of the familial cases. With the power of next generation sequencing (NGS) analysis, it is possible to analyze genes related to hereditary susceptibility to breast cancer and investigate the genetic etiology more thoroughly. In this study, we investigated 30 genes identified frequent pathogenic alleles in Turkish population. The study includes 495 unrelated individuals diagnosed with breast cancer who are selected for genetic testing according to NCCN criteria for hereditary breast cancer. All patients were analyzed by NGS for BRCA1/2 genes. Deletion/duplication investigation by Multiplex ligation-dependent probe amplification (MLPA) and massive sequencing of 30 breast cancer-related genes (Oncorisk Gene Panel) were performed in a stepwise manner. BRCA1/2 variants are the most frequent pathogenic variants which are found in 45 of 495 (9.1%) patients. Four previously unreported, novel, pathogenic variants of BRCA2 gene are identified. In four cases, exonic deletions of BRCA1/2 genes are determined and there is no duplication of these genes. NGS panel investigation involving other moderate-high risk genes contributed genetic diagnosis in an extra 39 out of 419 (9.3%) cases. Our study presents the cost effectiveness of the gene panel approach. We suggest that gene panels should be the first-tier genetic testing for hereditary breast cancer and MLPA analysis of BRCA1/2 genes should be investigated as a complementary method of NGS analysis.

Clinical and molecular evaluation of MEFV gene variants in the Turkish population: a study by the National Genetics Consortium.

Familial Mediterranean fever (FMF) is a monogenic autoinflammatory disorder with recurrent fever, abdominal pain, serositis, articular manifestations, erysipelas-like erythema, and renal complications as its main features. Caused by the mutations in the MEditerranean FeVer (MEFV) gene, it mainly affects people of Mediterranean descent with a higher incidence in the Turkish, Jewish, Arabic, and Armenian populations. As our understanding of FMF improves, it becomes clearer that we are facing with a more complex picture of FMF with respect to its pathogenesis, penetrance, variant type (gain-of-function vs. loss-of-function), and inheritance. In this study, MEFV gene analysis results and clinical findings of 27,504 patients from 35 universities and institutions in Turkey and Northern Cyprus are combined in an effort to provide a better insight into the genotype-phenotype correlation and how a specific variant contributes to certain clinical findings in FMF patients. Our results may help better understand this complex disease and how the genotype may sometimes contribute to phenotype. Unlike many studies in the literature, our study investigated a broader symptomatic spectrum and the relationship between the genotype and phenotype data. In this sense, we aimed to guide all clinicians and academicians who work in this field to better establish a comprehensive data set for the patients. One of the biggest messages of our study is that lack of uniformity in some clinical and demographic data of participants may become an obstacle in approaching FMF patients and understanding this complex disease.

Selective Bilateral Vestibular Neuropathy in a Turkish CMT1B Family With a Novel MPZ Mutation.

PURPOSE OF REVIEW: To report the findings in 12 members over 3 generations of a family with dominantly inherited Charcot-Marie-Tooth disease (CMT1B) due to a novel MPZ mutation, who all had moderately severe selective impairment of vestibular function with normal hearing. Methods used were video head impulse testing of the function of all 6 semicircular canals, Romberg test on foam, nerve conduction studies, and whole exome and Sanger sequencing. RECENT FINDINGS: All affected patients had a demyelinating neuropathy and a novel MPZ mutation: c.362A>G (chr1: 161276584, p.D121G). All also had normal hearing for age but a moderately severe impairment of semicircular canal function and a positive Romberg test on foam. SUMMARY: Some CMT mutations can impair vestibular function, presumably because of a vestibular nerve involvement but spare hearing. In such patients, impairment of vestibular function and impairment of proprioception contribute to imbalance.

PCR-Free Methodology for Detection of Single-Nucleotide Polymorphism with a Cationic Polythiophene Reporter.

This study presents a nonamplification-based nucleic acid assay for the detection of single-nucleotide polymorphism (SNP) associated with familial Mediterranean fever (FMF) besides polymerase chain reaction (PCR)-based methodologies. The major objective is to show the potential of the proposed assay for rapid screening of FMF in a Mediterranean region of 400 million population. The assay relies on binding difference of specially designed wild and mutant primers to the target genomic DNA, followed by determination of unbound primers by quick titration of a cationic polythiophene reporter. The fluorescent reporter exhibits signal transition from 525 to 580 nm in the presence of unbound primers, and it correlates the binding affinity of label-free primers to the homozygous wild and mutant genomes. As a proof of concept, 26 real samples are studied relying on the ON and OFF fluorescence signals of the cationic polythiophene reporter. The results are analyzed by principal component analysis (PCA), which provides clear separation of healthy and patient individuals. The further analysis by support vector machine (SVM) classification has revealed that our assay converges to 96% overall accuracy. These results support that the PCR-free nucleic acid assay has a significant potential for rapid and cost-effective screening of familial Mediterranean fever.

Serum motilin levels and motilin gene polymorphisms in children with functional constipation.

BACKGROUND: Functional constipation is an important clinical problem among chidren all over the world. Its main cause is not completely understood. Motilin is a gastrointestinal hormone that increases intestinal motility. In this study, we aimed to investigate the serum motilin levels and its relationship with stool consistency and motilin gene polymorphisms in constipated children. METHODS: In this study we investigated 91 constipated patients (mean age 6.84±3.55 years) and 100 healthy controls (mean age 7.78±4.25 years). Serum motilin levels were assessed by sandwich enzyme-linked immunosorbent assay. rs2281820 (c.44 C>T) and rs2281818 (c.66 C>T) mutations were evaluated for motilin gene polymorphisms. RESULTS: Serum motilin levels were significantly lower in constipated children than healthy controls (6.20±7.86 vs. 11.54±17.89 pg/mL, respectively, P=0.008). Serum motilin levels were significantly correlated with Bristol stool scale rate (r=0.193, P=0.011) in whole study group, but in the constipation group there was no significant correlation (r=-0.072, P=0.528). There were no differences in terms of presence or distribution of the polymorphisms of rs2281820 (c.44 C>T) and rs2281818 (c.66 C>T) in both groups. There was not a significant difference between different polymorphism groups regarding serum motilin concentrations in whole study group and also in both of the study groups. CONCLUSIONS: This study indicated for the first time that serum motilin levels decreased in constipated children. Further studies are needed to clarify whether motilin or motilin gene polymorphisms has a role in pathogenesis of functional constipation.

Relationship between plasminogen activator inhibitor-1 gene alterations and fibrosis in peritoneal dialysis patients.

Peritoneal fibrosis (PF) is a pathological change that occurs mostly long-term peritoneal dialysis (PD) patients, as a result of triggering the inflammatory response. Plasminogen activator inhibitor-1 (PAI-1) is an important molecule featured in the development of fibrosis. It has been shown in literature that PAI-1 gene alterations are associated with fibrosis in many tissues and organs. However, PAI-1 gene alterations in long-term PD patients have not yet been investigated. In this study, PAI-1 4G/5G polymorphism was examined by reverse hybridization, and all coding exons of the PAI-1 gene were examined by sequence analysis to provide treatment modification in patients with predisposition before fibrosis develops. The patients were divided into two groups according to ultrafiltration failure test and duration of PD treatment: those with suspected PF or a high probability of developing PF (36%) and those with a low probability of developing PF (64%). There was no significant difference between the two groups in findings such as peritoneal equilibration test (PET), Kt/V, the content of the PD solution used, peritonitis, and PAI-1 4G/5G polymorphism (P > .05). A total of eight gene alterations (rs2227660, rs2227668, rs2854233, rs41281004, rs61553169, rs368413856, rs2227684) were detected by sequence analysis, one of which was exonic (rs6092). When the genotype distributions of these variants were examined, no significant difference was found between the two groups. PAI-1 gene changes were not detected in patients with the probability of developing PF. There is a need for further studies involving other molecules responsible for predisposing to PF with larger patient populations in patients undergoing long-term PD treatment.

Investigation of the most common clinical and imaging findings and the role of tubulin genes in the etiology of malformations of cortical development

Background and aim: The number of reports on the role of tubulin gene mutations (TUBA1A, TUBB2B, and TUBB3) in etiology of malformations of cortical development has peaked in recent years. We aimed to determine tubulin gene defects on a patient population with simple and complex malformations of cortical development, and investigate the relationship between tubulin gene mutations and disease phenotype. Materials and methods: We evaluated 47 patients with simple or complex malformations of cortical development, as determined by radiological examination, for demographic features, clinical findings and mutations on TUBA1A, TUBB2B, and TUBB3 genes. Results: According to the magnetic resonance imaging findings, 19 patients (40.5%) had simple malformations of cortical development and 28 (59.5%) patients had complex malformations of cortical development. Focal cortical dysplasia was the most common simple malformation, lissencephaly was the most common coexisting cortical malformation, and corpus callosum anomalies were the most common coexisting extracortical neurodevelopmental abnormalities. None of the patients had genetic alterations on TUBA1A, TUBB2B, and TUBB3 genes causing protein dysfunction. On the other hand, the frequencies of some polymorphisms were higher when compared to the literature. Conclusion: It is crucial to identify the etiology in patients with malformations of cortical development in order to provide appropriate genetic counseling and prenatal diagnosis. We consider that multicenter studies with higher patient numbers and also including other malformations of cortical development-related genes are required to determine underlying etiological factors of malformations of cortical development patients.

Identification of PCDH19 Gene Mutations/Deletions in Patients with Early Onset Epilepsy.

BACKGROUND AND AIMS: PCDH19 gene, which encodes protocadherin 19, is associated with epilepsy and intellectual disability, mainly in affected females. The clinical manifestations are heterogeneous and the main features include early onset seizure, generalized or focal seizures sensitive to fever, and brief seizures occurring in clusters. The disorders exhibit a unique and unusual X-linked pattern of expression. We aimed to investigate PCDH19 mutations/deletions in patients with epilepsy and describe the clinical/molecular features. METHODS: PCDH19 gene was analyzed in 35 Turkish female patients from 34 families with early-onset epilepsy via direct sequencing and multiplex ligation-dependent probe amplification analysis. Additionally, array comparative genomic hybridization analysis was performed in patients with whole gene deletion. RESULTS: We identified 2 different heterozygous mutations in 2 unrelated probands (5. 7%) which were located in exon 1. Additionally, whole gene deletions were detected in dizygotic twin girls (5. 7%), who had distinct clinical features and the deletion was inherited from the unaffected father. The second twin suffered more severe clinical manifestations including autistic features, behavioral problems, mild-moderate mental retardation and seizures, which were under control with multidrug regimen when compared with the first twin. CONCLUSION: PCDH19 is a major causative gene in patients with epilepsy and further data is required to gain a better understanding of phenotype-genotype correlation. In addition to gene sequencing, deletion/duplication analysis will improve the molecular diagnosis in patients with clinical findings.

A toddler with a novel LEPR mutation.

There are numerous causes, such as environmental factors, medications, endocrine disorders, and genetic factors, that can lead to obesity. However, severe early-onset obesity with abnormal feeding behavior, mental retardation, dysmorphic features, organ-specific developmental abnormalities, and endocrine disorders suggest a genetic etiology. Mutations in genes related to the leptin-melanocortin pathway play a key role in genetic obesity. This pathway controls hypothalamic regulation of food intake. A few cases have been reported to have mutations in leptin (LEP) or leptin receptor (LEPR) genes. The cases had severe early-onset obesity, hyperphagia, and additional features, such as altered immune function, hypogonadism, and hypothyroidism. We present a 3-year-old male patient with severe early-onset obesity whose genetic analysis revealed a homozygous, novel, and pathogenic variant (c.1603+2T>C) in LEPR.

Phenotypic spectrum of CHARGE syndrome based on clinical characteristics

Background/aim: CHARGE syndrome is a rare autosomal dominant disease with multiple congenital anomalies and cognitive impairment, which is caused by mutations in the CHD7 gene. This study aimed to disclose the mild end of the phenotypic spectrum of CHARGE syndrome, which has a highly variable expressivity. Materials and methods: Twenty-one patients who had at least one of the major symptoms of CHARGE syndrome (coloboma, choanal atresia, characteristic ear anomalies, semicircular canal hypoplasia, and cranial nerve anomalies) were included in the study. All patients were tested for karyotype analysis and CHD7 gene mutation/deletion. Results: In the study population, 6 different mutations were detected in 5 patients, and 2 different polymorphisms were detected in the CHD7 gene in 3 patients. MLPA analysis of all coding exons of the CHD7 gene revealed no pathogenic deletion/duplication. Conclusion: CHARGE syndrome should be considered as a differential diagnosis to detect the mild end of the spectrum, even if the patient does not fit the criteria.

A 12-Year-Old Girl with Bilateral Coats Disease and ABCA4 Gene Mutation.

A 12-year-old girl with bilateral stage 2B Coats disease was screened meticulously for a possible underlying systemic disease as she was female and the disease was bilateral. Full systemic workout turned out to be unremarkable. However, an ABCA4 gene mutation was found in the genetic analysis. NDP and TINF2 gene mutations were not present. She was successfully treated with a bilateral, single intravitreal injection of dexamethasone implant and a single session of indirect laser photocoagulation with a relatively good anatomic and functional result. To the best of our knowledge, the present case is the only reported case of Coats disease with an ABCA4 gene mutation.