ДИФФЕРЕНЦИАЛЬНАЯ ДИАГНОСТИКА НАСЛЕДСТВЕННЫХ ФОРМ ВРОЖДЕННОЙ АНИРИДИИ С ПОЗИЦИЙ СОВРЕМЕННОЙ ГЕНЕТИКИ

Congenital aniridia (AN) is a hereditary autosomal dominant developmental disorder of the eye. Heterozygous mutations in the PAX6 gene and chromosomal rearrangements involving the 11p13 locus lie behind the pathogenesis of the AN. The key role of the PAX6 gene in the regulation of embryogenesis and the pleiotropic effect of this transcription factor explain the damage of several tissues of the anterior and posterior segments of the eye, brain structures, and the disturbance of morphogenesis and endocrine function of the pancreas observed in AN. Recently AN has been considered a syndromic pathology by several researchers. The review suggests classification and summarizes information on the clinical characteristics and genetic basis of various forms of AN. The problem of discrimination of clinical-genetic variants of the dysgenesis of the anterior segment of the eye and the differential diagnosis of PAX6-associated AN with WAGR syndrome, anterior dysgenesis, other rare monogenic and chromosomal syndromes is discussed, and the role of molecular diagnostics is emphasized.Врожденная аниридия (ВА) — наследственный аутосомно-доминантный порок развития глаз. В основе патогенеза ВА лежат гетерозиготные мутации в гене PAX6 и хромосомные перестройки, вовлекающие локус 11p13. Ключевая роль гена PAX6 в регуляции эмбриогенеза и плейотропность действия этого транскрипционного фактора объясняют возможность поражения сразу нескольких сред переднего отрезка глаз и глазного дна, структур головного мозга, а также нарушение морфогенеза и эндокринной функции поджелудочной железы, наблюдаемые при ВА. В последнее время ВА стала рассматриваться рядом исследователей как синдромальная патология. В обзоре собраны сведения о клинической характеристике, генетической основе различных форм ВА. Обсуждается проблема дискриминации клинико-генетических вариантов дисгенезии переднего отрезка глаза и дифференциальной диагностики PAX6-ассоциированной ВА с синдромом WAGR, дисгенезиями переднего отрезка глаз, другими редкими моногенными и хромосомными синдромами; подчеркивается роль молекулярной диагностики

Mild phenotype of CHAT-associated congenital myasthenic syndrome: case series

Congenital myasthenic syndrome with episodic apnea is associated with pathogenic variants in the CHAT gene. While respiratory disorders and oculomotor findings are commonly reported in affected individuals, a subset of patients only present with muscle weakness and/or ptosis but not apneic crises. In this case series, we describe five individuals with exercise intolerance caused by single nucleotide variants in the CHAT gene. The age of onset ranged from 1 to 2.5 years, and all patients exhibited a fluctuating course of congenital myasthenic syndrome without disease progression over several years. Notably, these patients maintained a normal neurological status, except for the presence of abnormal fatigability in their leg muscles following prolonged physical activity. We conducted a modified protocol of repetitive nerve stimulation on the peroneal nerve, revealing an increased decrement in amplitude and area of compound muscle action potentials of the tibialis anterior muscle after 15–20 min of exercise. Treatment with 3,4-diaminopyridine showed clear improvement in two children, while one patient experienced severe adverse effects and is currently receiving a combination of Salbutamol Syrup and pyridostigmine with slight positive effects. Based on our findings and previous cases of early childhood onset with muscle fatigability as the sole manifestation, we propose the existence of a mild phenotype characterized by the absence of apneic episodes

Pro-apoptotic and antiproliferative activity of human KCNRG, a putative tumor suppressor in 13q14 region

Deletion of 13q14.3 and a candidate gene KCNRG (potassium channel regulating gene) is the most frequent chromosomal abnormality in B-cell chronic lymphocytic leukemia and is a common finding in multiple myeloma (MM). KCNRG protein may interfere with the normal assembly of the K+ channel proteins causing the suppression of Kv currents. We aimed to examine possible role of KCNRG haploinsufficiency in chronic lymphocytic leukemia (CLL) and MM cells. We performed detailed genomic analysis of the KCNRG locus; studied effects of the stable overexpression of KCNRG isoforms in RPMI-8226, HL-60, and LnCaP cells; and evaluated relative expression of its transcripts in various human lymphomas. Three MM cell lines and 35 CLL PBL samples were screened for KCNRG mutations. KCNRG exerts growth suppressive and pro-apoptotic effects in HL-60, LnCaP, and RPMI-8226 cells. Direct sequencing of KCNRG exons revealed point mutation delT in RPMI-8226 cell line. Levels of major isoform of KCNRG mRNA are lower in DLBL lymphomas compared to normal PBL samples, while levels of its minor mRNA are decreased across the broad range of the lymphoma types. The haploinsufficiency of KCNRG might be relevant to the progression of CLL and MM at least in a subset of patients

Study of hereditary non-syndromic ophthalmic pathology of child population of the Karachay-Cherkess Republic: features and structure of nosological spectrum

V.V. Kadyshev1, A.V. Marakhonov1, S.I. Kutsev1,2, R.A. Zinchenko1,3 1 Research Centre of Medical Genetics of the Russian Academy of Medical Sciences, Moscow, &nbsp;Russian Federation 2 Pirogov Russian National Research Medical University, Moscow, Russian Federation 3 M.F. Vladimirsky Moscow Regional Research and Clinical Institute (MONIKI), Moscow,&nbsp; &nbsp;Russian Federation The publication is a continuation of the previously submitted data on the study of the epidemiology of ophthalmic diseases in children of the Karachay-Cherkess Republic. Genetic and epidemiological study of the population includes a research of a wide range of indicators. A burden assessment of the hereditary ocular pathology of the child population of the surveyed region and the data of molecular genetic diagnostics were published earlier. This article presents structure and features of a nosological spectrum of the visual organ hereditary pathology. Aim: to study the nosological spectrum and its features of hereditary non-syndromic ophthalmic pathology among the child population of the Karachay-Cherkess Republic. Patients and Methods: 90793 children from 10 regions of the Karachay-Cherkess Republic between the ages of 0 and 18 were examined, of which 121 people were enrolled in set. To solve the problem, genetic and epidemiological, clinical, paraclinical examination methods were used. Results: the structure and features of the nosological spectrum of non-syndromic hereditary ophthalmic pathology were determined in the child population of 10 regions of the Karachay-Cherkess Republic and the city of Cherkessk. Congenital malformations of the visual organ and hereditary pathology of the posterior segment of an eye (58%) make the main contribution to the prevalence. An overall prevalence of hereditary ocular pathology was at ratio 1:671. It was revealed that a large proportion of hereditary diseases of the visual organ with an autosomal dominant inheritance pattern (1:1163). The prevalence of autosomal recessive pathology was at ratio 1:2268 of people. Conclusion: autosomal dominant diseases make a greater contribution to the structure of the nosological spectrum — 1:1163. Congenital malformations of the visual organ and pathology of the posterior segment of the eye are prevalent in the structure of the pediatric nosological spectrum. Key words: epidemiology, genetics, hereditary pathology, nosological spectrum, children, Karachay-Cherkess Republic. For citation: Kadyshev V.V., Marakhonov A.V., Kutsev S.I., Zinchenko R.A. Study of hereditary non-syndromic ophthalmic pathology of child population of the Karachay-Cherkess Republic: features and structure of nosological spectrum. Russian Journal of Clinical Ophthalmology. 2019;19(1):7–12. About the authors:&nbsp; 1Vitalii V. Kadyshev — MD, PhD, Senior Researcher of the Laboratory of Genetic Epidemiology;&nbsp; 1Andrei V. Marakhonov — PhD, Biology, Senior Researcher of the Laboratory of Genetic Epidemiology;&nbsp; 1,2&nbsp;Sergei I. Kutsev — MD, PhD, Professor, Сorresponding Member of RAS, Head of the Research Centre of Medical Genetics, Head of the Department of Molecular and Cell Genetics;&nbsp; 1,3Rena A. Zinchenko — MD, PhD, Professor, Deputy Director of the Scientific and Clinical Study, Head of the Laboratory of Genetic Epidemiology.&nbsp; 1Research Center of Medical Genetics. 1, Moskvorechie str., Moscow, 115522, Russian Federation.&nbsp; 2Pirogov Russian National Research Medical University. 1, Ostrovityanova str., Moscow, 117997, Russian Federation.&nbsp; 3Moscow Regional Research and Clinical Institute. 61/2, Shchepkina str., Moscow, 129110, Russian Federation.&nbsp; Contact information:&nbsp;Vitalii V. Kadyshev, e-mail:&nbsp;[email protected].&nbsp;Financial Disclosure:&nbsp;no author has a financial or property interest in any material or method mentioned. There is no&nbsp;conflict of interests. Received&nbsp;06.12.2018.<br

Relative Frequencies of PAX6 Mutational Events in a Russian Cohort of Aniridia Patients in Comparison with the World&rsquo;s Population and the Human Genome

Genome-wide sequencing metadata allows researchers to infer bias in the relative frequencies of mutational events and to predict putative mutagenic models. In addition, much less data could be useful in the evaluation of the mutational frequency spectrum and the prevalent local mutagenic process. Here we analyzed the PAX6 gene locus for mutational spectra obtained in our own and previous studies and compared them with data on other genes as well as the whole human genome. MLPA and Sanger sequencing were used for mutation searching in a cohort of 199 index patients from Russia with aniridia and aniridia-related phenotypes. The relative frequencies of different categories of PAX6 mutations were consistent with those previously reported by other researchers. The ratio between substitutions, small indels, and chromosome deletions in the 11p13 locus was within the interval previously published for 20 disease associated genomic loci, but corresponded to a higher end due to very high frequencies of small indels and chromosome deletions. The ratio between substitutions, small indels, and chromosome deletions for disease associated genes, including the PAX6 gene as well as the share of PAX6 missense mutations, differed considerably from those typical for the whole genome

Clinical and genetic characteristics of a total or partial congenital aniridia

N.V. Sukhanova1, V.V. Kadyshev1, T.A. Vasilieva1, A.V. Marakhonov1, L.A. Katargina 2, S.I. Kutsev1, R.A. Zinchenko1,3 1Research Center for Medical Genetics, Moscow, Russian Federation 2Helmholtz National Medical Research Center for Eye Diseases, Moscow, Russian Federation 3N.A. Semashko National Research Institute of Public Health, Moscow, Russian Federation Aim: to assess clinical and genetic correlations between the specific clinical manifestations of congenital aniridia (CA) and the spectrum of mutations in the PAX6 gene (including chromosomal deletions involving the entire PAX6 gene or its regions). Patients and Methods: the study included 83 patients fr om 76 unrelated families with clinical patterns of congenital aniridia. The mean age of patients was 11.5±10.3 years. All patients underwent a comprehensive eye exam, molecular and genetic testing, as well as specialist consultation. To find a genetic cause of CA, the analysis of minor mutations in the PAX6 gene was performed by Sanger sequencing in order to determine the nucleotide sequence of 13 exons and adjacent intronic regions. Also, the number of gene copies of a chromosomal region 11p13 was evaluated by using multiplex reaction of Ligation-dependent Probe Amplification (MLPA) assay. In those cases wh ere a chromosomal deletion involving the WT1 gene was detected, a target fluorescent in situ hybridization (FISH) with a locus-specific DNA-probe for the WT1 gene was carried out to prove the MLPA results. The functional in vitro analysis of the impact of intronic nucleotide sequence variants was performed in the laboratory of functional genomics of the Research Center for Medical Genetics (RCMG) using the original technique. Results: the most common features associated with CA included foveal hypoplasia, nystagmus, disorders of the eye lens, and limbal stem cells deficiency (LSCD). These findings were reported in more than 60% of cases. Partial CA was significantly more prevalent in patients with splice-site mutations (p=0.004996) as compared to other mutation types. Optic nerve hypoplasia (p=0.04779), internal strabismus (p=0.010882), aniridia-associated keratopathy co-occurring with LSCD (p=0.013236) were diagnosed more frequently in patients with nonsense mutations. Secondary glaucoma was a more common finding in patients with the deletion of 3'-cis-regulatory region (p=0.020381). Conclusion: the analysis of genotypic and phenotypic correlations has revealed statistical regularities which may underpin the relationship between the clinical pattern of CA and the types of mutations. Keywords: congenital aniridia, foveal hypoplasia, PAX6, mutations, features of the clinical picture, geno-phenotypic correlations. For citation: Sukhanova N.V., Kadyshev V.V., Vasilieva T.A. et al. Clinical and genetic characteristics of a total or partial congenital aniridia. Russian Journal of Clinical Ophthalmology. 2023;23(1):2–8 (in Russ.). DOI: 10.32364/2311-7729-2023-23-1-2-8. </p

Hereditary etiology of non-syndromic sensorineural hearing loss in the Republic of North Ossetia–Alania

More than 50% of congenital hearing loss is hereditary, in which the majority form is non-syndromic. In this study we estimate the most prevalent pathogenic genetic changes in an Ossetian cohort of patients. This is useful for local public health officials to promote genetic counseling of affected families with regard to high allele frequencies of prevalent pathogenic variants and assortative mating in the community of people with hearing loss. In this study, genetic heterogeneity of hereditary non-syndromic sensorineural hearing loss (NSNHL) in a cohort of 109 patients and an assessment of the frequency of two GJB2 gene pathogenic variants in a cohort of 349 healthy individuals from the populations of the Republic of North Ossetia–Alania (RNO–Alania) were assessed. The molecular genetic cause of NSNHL in the GJB2 gene in RNO–Alania was confirmed in ~30% of the cases, including ~27% in Ossetians. In Russian patients, the most frequent variant is GJB2:c.35delG (~83%). The GJB2:c.358_360delGAG variant was found to be the most frequent among Ossetians (~54%). Two genetic variants in GJB2, c.35delG and c.358_360delGAG, accounted for 91% of GJB2 pathogenic alleles in the Ossetian patients. A search for large genome rearrangements revealed etiological cause in two Ossetian patients, a deletion at the POU3F4 gene locus associated with X-linked hearing loss (type DFNX2). In another Ossetian patient, a biallelic pathogenic variant in the MYO15A gene caused hearing loss type DFNB3 was identified, and in one Russian family a heterozygous MYH14 gene variant associated with dominant NSNHL was found. Thus, the informative value of the diagnosis was ~37% among all patients with NSNHL from RNO–Alania and ~32% among the Ossetians. These estimates correspond to the literature data on the fraction of recessive genetic forms of hearing loss within the affected population. The importance of this study consists not only in the estimation of the most prevalent pathogenic genetic changes in the Ossetian cohort of patients which could be useful for the public health but also in the genetic counselling of the affected families with regard to the high allele frequencies of revealed pathogenic variants as well as to the assortative mating in community of people with hearing loss

Genetic Variant c.245A&gt;G (p.Asn82Ser) in GIPC3 Gene Is a Frequent Cause of Hereditary Nonsyndromic Sensorineural Hearing Loss in Chuvash Population

Hereditary nonsyndromic sensorineural hearing loss is a disease in which hearing loss occurs due to damage to the organ of the inner ear, the auditory nerve, or the center in the brain that is responsible for the perception of sound, characterized by wide locus and allelic heterogeneity and different types of inheritance. Given the diversity of population of the Russian Federation, it seems necessary to study the ethnic characteristics of the molecular causes of the disease. The aim is to study the molecular and genetic causes of hereditary sensorineural hearing loss in Chuvash, the fifth largest ethnic group in Russia. DNA samples of 26 patients from 21 unrelated Chuvash families from the Republic of Chuvashia, in whom the diagnosis of hereditary sensorineural hearing loss had been established, were analyzed using a combination of targeted Sanger sequencing, multiplex ligase-dependent probe amplification, and whole exome sequencing. The homozygous variant NM_133261.3(GIPC3):c.245A&gt;G (p.Asn82Ser) is the major molecular cause of hereditary sensorineural hearing loss in 23% of Chuvash patients (OMIM #601869). Its frequency was 25% in patients and 1.1% in healthy Chuvash population. Genotyping of the NM_133261.3(GIPC3):c.245A&gt;G (p.Asn82Ser) variant in five neighboring populations from the Volga-Ural region (Russian, Udmurt, Mary, Tatar, Bushkir) found no evidence that this variant is common in those populations