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.

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.

Prenatal diagnosis of cystic hygroma cases in a tertiary centre and retrospective analysis of pregnancy results.

The aim of this study is to retrospectively examine invasive diagnostic methods, structural anomalies accompanying cystic hygroma, and pregnancy outcomes in cystic hygroma cases admitted to a tertiary centre. The population of the study consisted of 29 live foetuses with cystic hygroma in the foetal neck only in the first or second trimester. In the study, pregnant women who applied to our centre were included. Amniocentesis or chorionic villus sampling was performed for genetic analysis according to the weeks of the pregnant women who were diagnosed with cystic hygroma by ultrasound examination by two clinicians experienced in foetal anomaly. Of the pregnant women included in the study, 10 had normal karyotype, 12 had abnormal karyotype and 13 had structural abnormality. It is very important to provide genetic counselling to the families of foetuses with cystic hygroma with a multidisciplinary team approach consisting of neonatologists, paediatric surgeons and experienced sonographers. Implications for rehabilitationWhat is already known on this subject? Cystic hygroma, also known as cystic lymphangioma, is a congenital cystic malformation often seen in the first trimester, which occurs in the foetal neck due to the failure of the connections between the cervical lymphatic vessels and the jugular venous system to develop normally. Cystic hygroma may be isolated, but highly associated with foetal aneuploidy, hydrops fetalis, abnormal foetal nuchal translucency.What do the results of this study add? Invasive prenatal diagnostic tests (CVS or amniocentesis) should be performed in all patients with cystic hygroma, as cystic hygromas can be diagnosed by first trimester foetal genetic sonogram screening and are largely accompanied by chromosomal abnormalities.What are the implications of these findings for clinical practice and/or further research? In foetuses with cystic hygroma, foetal karyotyping, detailed sonography and their documentation, genetic counselling is important to families of cystic hygroma foetuses with a multidisciplinary team approach consisting of neonatologists, paediatric surgeons and maternal foetal medicine specialists, since there is a high risk for aneuploidy and foetal malformation.

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.

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.

The Complex Genetic Landscape of Hereditary Ataxias in Turkey and Implications in Clinical Practice.

BACKGROUND: The genetic and epidemiological features of hereditary ataxias have been reported in several populations; however, Turkey is still unexplored. Due to high consanguinity, recessive ataxias are more common in Turkey than in Western European populations. OBJECTIVE: To identify the prevalence and genetic structure of hereditary ataxias in the Turkish population. METHODS: Our cohort consisted of 1296 index cases and 324 affected family members. Polymerase chain reaction followed by Sanger sequencing or fragment analysis were performed to screen for the trinucleotide repeat expansions in families with a dominant inheritance pattern, as well as in sporadic cases. The expansion in the frataxin (FXN) gene was tested in all autosomal recessive cases and in sporadic cases with a compatible phenotype. Whole-exome sequencing was applied to 251 probands, selected based on the family history, age of onset, and phenotype. RESULTS: Mutations in known ataxia genes were identified in 30% of 1296 probands. Friedreich's ataxia was found to be the most common recessive ataxia in Turkey, followed by autosomal recessive spastic ataxia of Charlevoix-Saguenay. Spinocerebellar ataxia types 2 and 1 were the most common dominant ataxias. Whole-exome sequencing was performed in 251 probands with an approximate diagnostic yield of 50%. Forty-eight novel variants were found in a plethora of genes, suggesting a high heterogeneity. Variants of unknown significance were discussed in light of clinical data. CONCLUSION: With the large sample size recruited across the country, we consider that our results provide an accurate picture of the frequency of hereditary ataxias in Turkey. © 2021 International Parkinson and Movement Disorder Society.

Vestibular impairment in Charcot-Marie-Tooth disease.

OBJECTIVE: To find out if Charcot-Marie-Tooth (CMT) patients, who have peripheral vestibular as well as peripheral somatosensory impairment, have worse postural balance than those who do not. METHODS: We studied 32 patients with various CMT phenotypes and genotypes. Vestibular function was measured with the video head impulse test (vHIT) which tests vestibulo-ocular reflex (VOR) gain from each of the six semicircular canals in response to rapid head rotations. Postural balance was evaluated with a battery of four postural tests with emphasis on the modified clinical test of sensory integration in balance (mCTSIB). RESULTS: Half of the 32 patients had some impairment of vestibular function ranging from mild, affecting only 1-2 semicircular canals, to almost total affecting all 6 semicircular canals. Their mCTSIB scores correlated with VOR gain from the vertical rather than from the lateral semicircular canals. The worse the vertical VOR gain the worse the mCTSIB score. CONCLUSION: We propose that any CMT patient could have clinically inapparent vestibular impairment that can be easily measured with the vHIT. This vestibular impairment could be contributing to their imbalance and could respond to a focused vestibular rehabilitation program.

Unexpected Coexistence of a Derivative t(21;21) and Complementary Mosaic r(21) in a Female with Multiple Miscarriages.

The case presented here describes a female patient with recurrent miscarriages and a normal microarray analysis result. However, the coexistence of a robertsonian (21;21) translocation and complementary mosaic ring chromosome 21 was detected by karyotyping and FISH analysis. Partial trisomy 21 was found with QF-PCR and microarray analysis in one of the fetuses. The aim of this report was to emphasize the diagnostic importance of conventional cytogenetics.

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.

Identification of an AR mutation in Klinefelter syndrome during evaluation for penoscrotal hypospadias.

Genital anomalies, ranging from female genitalia to milder degrees of undervirilization, are rarely reported in Klinefelter syndrome, in which a male is classically expected to be born with male external genitalia. Though androgen insensitivity syndrome (AIS) is one of the possible pathogenic mechanisms also in Klinefelter syndrome with genital anomalies, to date the AR gene has not been analyzed in any of the published cases of Klinefelter syndrome of the milder phenotype, except for those patients presenting with a severe phenotype, such as female external genitalia.Lack of interest in considering androgen insensitivity in Klinefelter syndrome with a milder phenotype of genital anomalies may impede its identification through an accurate diagnosis. We present a 14-month-old boy with penoscrotal hypospadias, micropenis, and a ventral penile chordee abnormality who was observed to have both a 47,XXY karyotype and a known missense mutation in the ARgene that was inherited from his mother. Although it is recommended that Klinefelter syndrome be considered in the differential diagnosis of penoscrotal abnormalities, mutations in specific genes involved in androgen synthesis or responsiveness should also be investigated.

Assessment of sleep problems in children with familial Mediterranean fever.

AIMS: This study aimed to investigate sleep patterns, sleep disturbances and possible factors that are associated with sleep disturbances among children with familial Mediterranean fever (FMF). PATIENTS AND METHODS: Fifty-one patients with FMF and 84 age- and sex-matched healthy controls were enrolled in the study. The patients who had an attack during the last 2 weeks were not included. Demographic data, FMF symptoms, disease duration, dose of colchicine, disease severity score, number of attacks in the last year, MEFV mutation and serum C-reactive protein (CRP) levels were recorded for each patient. A Children's Sleep Habits Questionnaire was performed. RESULTS: The total sleep scores of the patients with FMF were significantly higher than the control group. Total sleep durations were similar between FMF patients and controls. Children with FMF had significantly higher scores regarding sleep-onset delay, sleep anxiety, night wakings and sleep-disordered breathing when compared to healthy controls. There was a significant positive correlation between number of attacks in the last year and sleep onset delay, night wakings and sleep disordered-breathing. Disease severity score and CRP levels were not associated with any of the subscale scores. The patients with exertional leg pain had significantly higher total sleep scores than the ones without. Furthermore, patients with exertional leg pain had significantly higher subscale scores regarding sleep onset delay, parasomnias and sleep-disordered breathing. CONCLUSION: This study showed for the first time that children with FMF had more sleep disturbances than their healthy peers. Higher numbers of attacks and exertional leg pain were associated with poor sleep quality. In conclusion, this study underlines the need to assess and manage sleep problems in children with FMF.

Analysis of first-trimester combined test results in preparation for a cell-free fetal DNA era.

OBJECTIVE: To survey experience with the first-trimester combined test (FCT) for trisomy 21 (T21) in different risk score groups to determine the most useful clinical application of cell-free fetal DNA (cffDNA) screening. METHODS: In a retrospective study, the records of FCT results obtained at a center in Turkey between January 2009 and January 2014 were reviewed. The FCT results and rates of uptake of invasive diagnostic testing were compared among different risk score groups. RESULTS: FCT results were available for 4804 pregnancies; 276 (5.7%) had IDT results. Ten (72.7%) of 11 cases of T21 had a risk score of 1:300 or more. The IDT uptake rates were 54.5%, 51.9%, and 47.4% at risk scores of 1:100 or more, 1:200 or more, and 1:300 or more, respectively. In the group at intermediate risk (1:1001-1:3000), no pregnancy had an FCT result of both low pregnancy-associated plasma protein A and high free ß-human chorionic gonadotropin, but 30 (3.9%) of 766 pregnancies had both advanced maternal age and high ß-human chorionic gonadotropin. CONCLUSION: cffDNA screening should be used to optimize IDT uptake in pregnancies with a risk score of 1:101-1:1000. The selective power of the FCT diminishes beyond the 1:1001 score and cffDNA screening cannot yet be recommended routinely.

Cardiac autonomic functions in children with familial Mediterranean fever.

Familial Mediterranean fever (FMF) is the most common inherited autoinflammatory disease in the world. The long-term effects of subclinical inflammation in FMF are not well recognized. Some studies have suggested that FMF is associated with cardiac autonomic dysfunction in adult FMF patients. The objective of this study was to investigate the cardiac autonomic functions in pediatric FMF patients by using several autonomic tests. Thirty-five patients with FMF and 35 healthy controls were enrolled in this cross-sectional study. Demographic data, disease-specific data, and orthostatic symptoms were recorded. In all participants, 12-lead electrocardiography (ECG), 24 h ambulatory electrocardiographic monitoring, transthoracic echocardiography, treadmill exercise test, and head upright tilt-table (HUTT) test were performed. The heart rate recovery (HRR) indices of the two groups were similar. Also, chronotropic response was similar in both groups. The time-domain parameters of heart rate variability (HRV) were similar in both groups, except mean RR (p = 0.024). Frequencies of ventricular and supraventricular ectopic stimuli were similar in both groups. There were no statistically significant differences between the groups in average QT and average corrected QT interval length, average QT interval dispersion, and average QT corrected dispersion. There was no significant difference between the two groups regarding the ratio of clinical dysautonomic reactions on HUTT. However, we observed a significantly higher rate of dysautonomic reactions on HUTT in patients with exertional leg pain than that in patients without (p = 0.013). When the fractal dimension of time curves were compared, FMF patients exhibited significantly lower diastolic blood pressure parameters than controls in response to HUTT. Cardiovascular autonomic dysfunction in children with FMF is not prominent. Particularly, patients with exertional leg pain are more prone to have dysautonomic features. Further studies are needed to elucidate the exact mechanisms leading to impaired cardiac autonomic functions in FMF.

Termination of pregnancy for fetal abnormalities: main arguments and a decision-tree model.

INTRODUCTION: By looking through our ethical committee cases, we demonstrate the main arguments we use for making a judgment in face of fetal abnormalities. Our decision making model is a simplified algorithm of the arguments and concepts we use in scientific-ethic discussion. MATERIALS AND METHODS: A retrospective analysis was conducted from single, tertiary referral center of patients evaluated for fetal abnormalities from 2004 to 2014. We hypothesized that all our judgments would fit into a decision-tree model. RESULTS: 553 fetal abnormality cases were discussed, 348 (63%) were given termination of pregnancy (TOP) proposal. When detected <24 weeks, fetuses with chromosomal abnormality/genetic disorders (n:100) and with mental retardation risk (n:93) ended up with TOP proposal. For incompatibility with life cases (n:111) and the multimorbidity cases (n:44) the committee suggest TOP, regardless of gestational age. The highest family approval ratios were in chromosomal abnormalities/genetic disorders group (93%), and the lowest figures were in mental retardation risk group (80%). DISCUSSION: Continuously changing literature on prenatal and postnatal therapy options and the long term outcome of various fetal abnormalities influence committee decisions. Theoretical high success rates and inconsistent data on long term prognosis of some anomaly groups resulted in heterogenous decisions and various approval ratios.

Risk factors for subclinical inflammation in children with Familial Mediterranean fever.

Familial Mediterranean fever (FMF) is the most common autosomal recessive inherited inflammatory disease characterized by attacks of painful inflammation. Some patients with FMF have subclinical inflammation persisting between the attacks. We aimed to identify the demographic, clinical and genetic risk factors for subclinical inflammation in children with FMF. The medical records of the children with FMF were evaluated retrospectively for acute-phase response along with gender, age at the onset of symptoms and at the time of diagnosis, clinical signs and symptoms, the presence of amyloidosis and MEFV genotype. Patients with persistently elevated acute-phase response between the attacks were considered to have subclinical inflammation. Patients with or without subclinical inflammation (Group 1 and Group 2, respectively) were compared for the parameters defined above. Independent risk factors for subclinical inflammation were identified by multivariate logistic regression analysis. There were 105 children (male/female: 52/53) who were compliant on colchicine treatment. Subclinical inflammation was detected in 22 (20 %) patients. Group 1 had significantly higher rate of myalgia, arthritis/arthralgia, erysipelas like erythema, amyloidosis, protracted febrile myalgia and M694V mutation compared with Group 2. However, only the presence of myalgia and erysipelas like erythema were found to be independent risk factors for subclinical inflammation (OR 9.8 and 5.9, respectively). Children with FMF who have myalgia and erysipelas like erythema during the attacks are particularly at risk of ongoing inflammation and should be closely monitored for subclinical inflammation even during attack-free periods.

Alpha-2-adrenergic receptor gene polymorphism in Turkish population with irritable bowel syndrome.

BACKGROUND/AIMS: Irritable bowel syndrome is a multifactorial functional gastrointestinal disorder affecting more than 10% of world population. Genetic component in pathophysiology of irritable bowel syndrome is still unknown. The aim of this study was to examine the potential impact of C-1291G polymorphism in α2-adrenergic receptor gene promoter region in the etiology of the disease. MATERIALS AND METHOD: This prospective case-control study included 100 irritable bowel syndrome patients and 100 healthy controls adjusted for sex and age. The subjects were genotyped by using polymerase chain reaction amplification of the promoterregion of α2-adrenergic receptor gene. Allele and genotype frequencies were compared in patient and control groups. The study was approved by the University ethics committee. RESULTS: The frequency of C allele was 72% and 75%, G allele was 28% and 25% in patient and control groups, respectively (p>0.05). We found that the frequencies of C1291C, C1291G, and G1291G genotypes were 50, 44, and 6%, respectively, in the patient group and 51, 48, and 1%, respectively, in the control group (p>0.05). The subgroup analysis of patients revealed that 70 patients were constipation-predominant, 27 patients were alternating diarrhea and constipation, and 3 patients were diarrhea-predominant irritable bowel syndrome. CONCLUSION: No significant association was observed between α2-adrenergic receptor gene C-1291G polymorphism and irritable bowel syndrome in Turkish population. The high number of constipation predominant irritable bowel syndrome and very low number of diarrhea predominant irritable bowel syndrome patients might be the reason for statistical non-significance since α2-adrenergic receptor gene is found to be responsible for mediating intestinal antisecretory action and probably is involved in the pathogenesis of diarrhea predominant irritable bowel syndrome. Further investigations are needed.

Lack of association of childhood partial epilepsy with brain derived neurotrophic factor gene.

Brain-derived factor (BDNF) is a member of neurotrophin family and is localized and upregulated in areas implicated in epileptogenesis. Several lines of evidence make the BDNF gene a plausible candidate gene for predisposition to epilepsy. In this study, we tested that BDNF might be involved in the etiology of childhood PE. To assess whether BDNF gene C270T polimorphism could be implicated in vulnerability to PE, we conducted a case-control association analysis (112 partial epileptic and 100 controls) in Turkish children. Epileptic children were divided into two groups: 1--idiopathic (n = 85) and 2--symptomathic epilepsy (n = 27). There was no significant difference in genotypic distribution and allelic frequencies of the BDNF gene C270T polimorphism between the PE and control groups. However, the BDNF gene TT genotype was more frequently seen in the epileptic children (15 versus 11 patients, resp.). Interestingly, in the epilepsy group, both two children with TT genotype have posttraumatic epilepsy. The data indicate a possible association with the 270T genotype of the BDNF gene with a posttraumatic epilepsy. To draw any conclusion, further studies using larger sample sizes should be carried out in various ethnic populations in childhood epilepsies.

New mutations in the ATM gene and clinical data of 25 AT patients.

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar degeneration, immunodeficiency, oculocutaneous telangiectasias, chromosomal instability, radiosensitivity, and cancer predisposition. The gene mutated in the patients, ATM, encodes a member of the phosphatidylinositol 3-kinase family proteins. The ATM protein has a key role in the cellular response to DNA damage. Truncating and splice site mutations in ATM have been found in most patients with the classical AT phenotype. Here we report of our extensive ATM mutation screening on 25 AT patients from 19 families of different ethnic origin. Previously unknown mutations were identified in six patients including a new homozygous missense mutation, c.8110T>C (p.Cys2704Arg), in a severely affected patient. Comprehensive clinical data are presented for all patients described here along with data on ATM function generated by analysis of cell lines established from a subset of the patients.