[Clinical and molecular genetic features of cases of isolated hypogonadotropic hypogonadism, associated with defects in GNRHR genes].

Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder characterised by lack of pubertal development and infertility, due to deficient production, secretion or action of gonadotropin-releasing hormone (GnRH). Clinically, there are variants of CHH with hypo-/anosmia (Kalman syndrome) and normosmic hypogonadotropic hypogonadism. Given a  growing list of gene mutations accounting for CHH, the application of next generation sequencing (NGS) comprises an excellent molecular diagnostic approach because it enables the simultaneous evaluation of many genes. Biallelic mutations in GNRHR gene lead to the development of hypogonadotropic hypogonadism with normosmia. In this paper, we describe 16 patients with proven GnRH resistance and estimate the frequency of pathogenic variants in the GNRHR gene in the Russian population.

[PROMISING OPTIONS FOR MEDICAL ROBOTICS APPLICATION IN SUPPORT OF CREW LIFE ACTIVITIES AND MITIGATION OF MEDICAL RISKS DURING SPACE FLIGHT].

Theme of the article is integration of robotics, medical robots that embody the bio-engineering technology specifically, into the spacecrew medical care system.

[Follicular cell (papillary and follicular) thyroid carcinoma, genetic inheritance, and molecular diagnostic markers].

OBJECTIVE: To determine the genetic forms of follicular cell thyroid carcinoma (FCTC) (papillary and follicular thyroid carcinoma (PTC and FTC)), to identify criteria to individually predict the development of the same disease for relatives, and to assess the role of molecular markers in the diagnosis, prognosis, and treatment of this disease. SUBJECTS AND METHODS: One hundred and ninety adult patients aged 20 to 84 years with histologically verified PTC and FTC and 20 children (12 patients with PTC and 8 with benign thyroid tumors) aged 2 to 16 years were examined. To assess the role of the BRAF gene as a molecular marker for thyroid carcinoma, DNA was isolated from the thyroid tumor tissue of 29 patients, which had been obtained by fine-needle aspiration biopsy (FNAB) and scraping and swabbing the cytological specimen previously showing an area containing tumor cells. A BRAF c.1799T>A (p.V600E) mutation in the FNAB specimens was tested by allele-specific ligation, followed by PCR amplification. RESULTS: The examinees' families were found to have a segregation of benign thyroid tumor and nontumor diseases (13.6%). Neoplasias of different sites were observed in 15% of the patients' relatives. Multiple primary tumors were detected in 6.1% of the patients and in 25% of the examined children (3/12). PTC was ascertained to accumulate as two clinical forms in the families. One form belongs to familial PTC (FPTC) in which two or three generations of relatives in the family are afflicted by only PTC and have a more severe phenotype of the disease. The other includes an association of FPTC with papillary kidney cancer. Furthermore, FPTC and PTC may be a component of multitumor syndromes, such as multiple endocrine neoplasia type 1, Cowden syndrome, and familial adenomatous polyposis. The familial hereditary forms of FCTC were generally revealed in 4.2% of the patients. BRAF v600E mutations were found in only 3 patients with Stages II and III PTC and were not in all the 12 children with PTC. CONCLUSION: The found clinical manifestation of the hereditary forms of FCTC permits the identification of people at high risk for this disease. No correlation between somatic BRAF mutations with a less favorable course in PTC can be noticed because there are few observations. Analysis of published data on the role of molecular markers in FCTC has shown that the existing specific somatic changes complement information in the differential cytological diagnosis when examining FNAB specimens.

[Rigid spine congenital muscular dystrophy produced by SEPN1 mutations (RSMD1)].

RSMD1 is a rare autosomal recessive disorder. Unlike most congenital muscular dystrophies, early motor improvement and normal CPK are typical, while in contrast to structural myopathies there is no specific muscle morphology. Rigid spine, early scoliosis and joint contractures are characteristic. We diagnosed RSMD1 in a 27-year-old Russian female with previous diagnosis of unspecified myopathy. DNA test detected compound heterozygosity for two SEPN1 mutations: already known missence-mutation c.1397G>A (p.Arg466Gln) and novel frame-shift mutation c.683_689dup7 leading to preterm stop-codon.

[The audiological phenotype and the prevalence of GJB2-related sensorineural loss of hearing in the infants suffering acoustic disturbances].

The objective of the present work was to study specific features of the audiological phenotype and the prevalence of GJB2-related sensorineural hearing loss (SNHL) in the infants suffering acoustic disturbances. The study included 264 children with bilateral non-syndromic sensorineural loss of hearing diagnosed during the first year of life by means of detailed audiological examination that included tympanometry, registration of short-latency auditory action potentials (SLAAP), delayed evoked otoacoustic emission (DEOAE), distortion product-frequency otoacoustic emission (DPFOAE), and auditory brain-stem response (ABR). In addition, stationary acoustically evoked responses (SAER) were recorded in 38 children presenting with hearing impairment associated with GJB2-related sensorineural loss of hearing. The follow-up dynamic study involved 113 children subjected to repeated audiological examination. The study revealed the genotype with pathological mutations in 182 (69.0%) children including 171 (64.8%) ones with biallelic mutations and 11 (4.2%) with a single mutation (heterozygous genotype). Eighty two (31.0%) children had genotype without mutations. A total of 21 different mutations and 30 different genotypes were identified. Analysis of the family histories of the children showed that neither the absence of relatives suffering from hearing impairment nor the presence of risk factors of acquired hearing impairment excludes the possibility of GJB2-related sensorineural loss of hearing in the infants. Otoacoustic emission fails to be registered in the majority of the children with the altered genotype (87%) during the stay in the maternity house. Mutations in the GJB2 gene are most frequently diagnosed in the patients with the moderate, moderately severe, and severe loss of hearing. At the same time, almost half of the infants presenting with the mild loss of hearing were found to exhibit changes in the GJB2 gene. The thresholds of registration of short-latency auditory action potentials remain stable in 90.0% of the children presenting with GJB2-related sensorineural loss of hearing which makes it possible to choose the strategy of their rehabilitative treatment (the use of hearing aids or cochlear implantation) during the very first months of life and predict the favourable outcome of cochlear implantation and hearing aid measures. The results of the present work illustrate the importance and practical significance of genetic studies (GJB2 gene tresting) of the infants suffering sensorineural loss of hearing and other acoustic disturbances for the elucidation of etiology of these conditions, prognosis of the disease, and the choice of the strategy for its treatment.

[Stargardt's disease and abiotrophy of Franceschetti (fundus flavimaculatus): pathogenetic, clinical, and molecular genetic characteristics].

The article presents a review of literature on Stargardt's disease and abiotrophy of Franceschetti. Etiopathogenetic, clinical and molecular genetic characteristics are covered. Clinical and genetic classifications of the diseases are provided.

[Morphological changes in retina and optic nerve head in patients with Leber's hereditary optic neuropathy].

OBJECTIVE: To study morphological changes of the macula and the peripapillary nerve fiber layer in patients with Leber's hereditary optic neuropathy (LHON). MATERIAL AND METHODS: A total of 21 patients (40 eyes) with LHON and 17 healthy volunteers (33 eyes) of the control group were assessed. Optical coherence tomography (OCT) on RTVue-100 for retina and optic nerve head assessment was performed in all cases. RESULTS: Thinning of the inner retinal layers in nasal and inferior parafoveal sectors takes place in the early acute period of the disease and then spreads to the rest of the macular area. The retinal nerve fiber layer (RNFL) in the early acute period is of more thickness in temporal, inferior, and superior sectors in comparison to controls, but later gradually becomes thinner, especially in the temporal sector. In the late period significant peripapillary RNFL thinning is present in all sectors. CONCLUSION: OCT reveals certain structural changes in the macular area and the peripapillary RNFL that are characteristic of Leber's hereditary optic neuropathy and together with clinical presentation can substantiate the diagnosis.

[The mutation spectrum of the GJB2 gene in Belarussian patients with hearing loss. Results of pilot genetic screening of hearing impairment in newborns].

A total of 111 unrelated probands and their 8 sibs from Grodno oblast (Belarus) with bilateral isolated sensorineural hearing impairment were studied for the presence of mutations in the connexin 26--GJB2gene. Mutations were detected in 51 probands (46% of the sample). A significantly higher frequency of the GJB2gene mutations was observed in familial cases of the disease with the autosomal recessive type of inheritance (in 78% of families). Detected peculiarities of the GJB2 gene mutation spectrum demonstrated that use of the algorithm, which was developed for Russian patients, is optimal for the molecular study of patients from Be- larus. In the sample of patients with hearing loss, the highest (among other similar samples studied in the world) allele frequency of c.313_326de114 mutation (7% out of all pathological GJB2 alleles) was registered; Polish origin of this deletion was suggested. It was demonstrated that detection of the GJB2 gene mutation on only one patient's chromosome is insufficient to confirm a molecular genetic diagnosis of hearing loss of the DFNB1 genetic type (autosomal recessive hearing loss caused by the GJB2 gene mutations). Pilot screening in the presence of GJB2 gene mutations in newborns from Grodno oblast was conducted. The material from 235 children was studied during the screening; nine heterozygous carriers of the mutation were found. The c.35delG mutation was detected in a homozygous state in a single newborn (hearing loss of moderate severity was subsequently audiologically confirmed in this child).

[New recurrent extended deletion, including GJB2 and GJB6 genes, results in isolated sensorineural hearing impairment with autosomal recessive type of inheritance].

Hereditary hearing loss with the autosomal recessive type of inheritance of the DFNB 1 genetic type, caused by mutations in the GJB2 gene, is the main reason of innate non-syndromal hearing impairment in most developed countries of the world (including Russia). Intragenic point mutations prevail among the GJB2 gene defectors; however, extended deletions in the DFNB1 locus are also found with considerable frequency in some populations (for example, Spain, Great Britain, France, United States, and Brazil). Among the four known extended deletions, only one deletion affects directly the GJB2 gene sequence and was described in a single family. A new extended deletion in the GJB2 and GJB6 gene sequences (approximately 101 kb in size; NC_000013.10:g.20,757,021_20,858,394del), detected in three unrelated Russian patients, was described and characterized. Ingush origin of this mutation is assumed. If the new deletion is frequent, its detection is very important for the genetic consulting of families with hereditary hearing impairment.

[Genetic and clinical characteristics of 22q11.2 deletion syndrome].

In a group of 140 patients with typical phenotype, the 22q11.2 microdeletion was detected in 43 patients (32%) using FISH and MLPA methods. There were no deletions of other chromosomal loci leading to phenotypes similar to the 22q11.2 deletion syndrome (22q11.2DS). Sequencing of the TBX1 gene did not detect any mutations, except for some common neutral polymorphisms. For the first time in the Russian Federation, the diagnostic efficiency of 22q11.2DS appeared to be 32%, as a result of the application of a combination of genetic approaches for a large group of patients with suspected 22q11.2DS.

[Modern opportunities and prospects for studying pathogenesis, diagnosing and treating hereditary optic neuropathies].

OBJECTIVE: To evaluate modern opportunities and prospects for studying pathogenesis and improving diagnostics and treatment of hereditary optic neuropathies (HON). MATERIAL AND METHODS: The article presents summarized data on the pathogenesis, diagnostics, and treatment of HON based on modern methods of assessment. RESULTS: The results of long-term worldwide studies and those performed in the Research Institute of Eye Diseases in collaboration with several other institutions are presented. Genetic testing for mitochondrial and nucleus DNA mutations that have a known association with Leber's hereditary optic neuropathy (LHON) and autosomal dominant optic neuropathy (ADON) allow verification only in half of the cases. Particular features of hereditary diseases, such as incomplete penentrance, variable expression, clinical polymorphism, difficulties in detection of hereditary sings, and genetic heterogeneity, are shown to complicate the diagnosis of HON. Spectral retinal tomography revealed characteristic morphometric changes in the macular region and peripapillary nerve fiber layer in the acute stage of LHON. Hereditary optic neuropathies result from a genetically determined decrease in mitochondrial respiratory chain complexes activity, which is associated with a decrease in ATP production. From that standpoint, studying of mitochondrial oxidative phosphorylation biochemical defects in LHON and ADON is an option for detection of mitochondrial dysfunction. Results of a newly proposed method of mitochondrial membrane potential assessment in skin fibroblasts, which can be used for differential diagnosis of mitochondrial optic nerve diseases, are presented. Possible therapeutic measures for HON are discussed. CONCLUSION: In the prevailing number of cases the described clinical, molecular genetic, and cytological methods ensure proper diagnosis of hereditary optic neuropathies. Prospects of HON treatment, rather ambiguous, are associated with further studying of pathogenesis, development of drugs and gene therapy.

[Clinical and molecular genetic analysis of hereditary optic neuropathies].

DNA samples of 50 patients with optic neuropathy (ON) associated with congenital cataract were studied to find 3 major mt-DNA mutations (m.11778G>A, m.3460G>A, m.14484T>C), mutations in "hot" regions of OPA 1 gene (exons 8, 14, 15, 16, 18, 27, 28) and in the entire coding sequence of OPA3 gene for molecular genetic confirmation of diagnosis of hereditary Leber and autosomal dominant ON. Primary mutations of mtDNA responsible for hereditary Leber ON were found in 16 patients (32%). Pathogenic mutations of OPAl gene (c.869G>A and c. 2850delT) were identified in 2 patients (4%), these mutations were not found in the literature. OPA3 gene mutations were not revealed.

[Population frequency and age of c.806C > T mutation in CYB5R3 gene as cause of recessive congenital methemoglobinemia in Yakutia].

Type-1recessive congenital methemoglobinemia (RCM) is a rare autosomal disease characterized by a deficiency of the soluble form of nicotineamide adenine dinucleotide (NADH)-cytochrome b5 reductase (b5R) and clinically manifests as cyanosis of skin and mucous membranes. In the Russian Federation, type-I RCM is widely disturbed in Yakutia due to the local founder effect. The molecular genetics cause of type-I RCM in Yakutia is mutation c.806C > T in the CYB5R3 gene. In this work we used 13 polymorphic markers, which flanking the CYB5R3 gene to establish the founder haplotype. The age of the mutation was estimated as about 285 +/- 135 years. In this work, we have evaluated the frequency of the c.806 C > T mutation in Yakutia, which averaged 55 : 1000 Yakuts. The calculated frequency of disease was 1: 1250 Yakuts.

[Clinic and genetic polymorphism of Brugada syndrome in Russian patients, caused by mutation in SCN5A gene].

Brugada syndrome (BrS) is an inherited cardiac arrhythmic disorder, characterized by ST-segment elevation in right precordial leads V1-V2>2 mm, pseudo right bundle branch block (RBBB), T-wave inversion and an increased risk of cardiac sudden death (SCD) due to molymorphic VT. It is estimated to be responsible for 12% of SCD cases and about 20% of deaths in patients with structurally normal hearts in autopsy. Mutations in the SCN5A gene account 15-30% of all cases. Clinical, instrumental and genetic analyses were performed for 25 Russian probands with BrS (19 males and 6 female). Phenotype-genotype correlation was studied in SCN5A-positive and SCN5A-negative patients. Rare genetic variants in SCN5A gene were found in 7 of 21 Russian probands (28%). Two variants affect protein splicing (c.IVS16DS-5A>G and c.IVS24AS+1G>A), three missense mutations (p,Y87C, p.R893H and p.S1787N), one in-frame deletion p.del848l, and one non-sense-mutation p.E553X. All mutations were unique for each family. There were no clinical or instrumental parameters were found to be effective in prediction of SCN5A mutations. The protocols of genetic counceling for SCN5A-positive and SCN5A-negative families were established.

[Hereditary optic neuropathies: clinical and molecular genetic characteristics].

The article presents a review of literature on hereditary optic neuropathies: Leber mitochondrial hereditary optic neuropathy, autosomal dominant and autosomal recessive optic neuropathies, X-linked optic atrophy. Clinical and molecular genetic characteristics are covered. Isolated optic neuropathies, as well as hereditary optic disorders, being a part of a complex syndromic disease are described.

[The spectrum of CLCN1 gene mutations in patients with nondystrophic Thomsen's and Becker's myotonias].

Thomsen's and Becker's diseases are the most prevalent nondystrophic myotonias. Their frequency varies, according to different sources, from 1 : 100 000 to 1 : 10 000. Thomsen's myotonia is autosomal dominant, and Becker's myotonia is autosomal recessive. Both diseases result from mutations of the CLCN1 gene encoding chloride ion channels of skeletal muscles. Molecular genetic analysis of the CLCN1 gene has been performed in patients with diagnoses of nondystrophic Thomsen's and Becker's myotonias living in the Russian Federation. A sample of 79 unrelated probands with nondystrophic Thomsen's and Becker's myotonias and 44 their relatives has been formed in the Laboratory of DNA Diagnosis of the Medical Genetic Research Center of the Russian Academy of Medical Sciences. Forty CLCN1 gene mutations have been found in a total of 118 chromosomes of 66 probands, including 21 familial and 45 sporadic cases. About half the mutations detected (45%) have been found for the first time; they are not described in the SNP database (ncbi.nlm.nih.gov). The following mutations (substitutions) have been detected in more than one chromosome, accounting for a total of 59.3% of chromosomes with mutations: Glyl90Ser (5.9%), c.1437-1450del14 (9.3%), Ala493Glu (5.1%), Thr550Met (3.4%), Tyr686Stop (5.1%), and Arg894Stop (30.5%).

[Heterozygous carrier rate for type I-IV proximal spinal muscular atrophy in Chuvashes, Udmurts, and residents of the Moscow region].

The first estimation of the heterozygous carrier rates for the SMN1 gene deletions and SMN2 gene duplications in populations of Russia has been performed. The numbers of SMNgene copies have been determined in samples from Chuvash and Udmurt populations, as well the population of the Moscow region, by means of multiplex ligation-dependent probe amplification. The heterozygous carrier rates for the CMA gene were 2.7% (1 : 37 people), 2.8% (1 : 36 people), and 2.8% (1 : 36 people) in Chuvashes, Udmurts, and residents of the Moscow region, respectively. The SMN2 duplication frequencies have been determined in the studied groups. It is 1.5, 4, and 2.5% in Chuvashes, Udmurts, and residents of the Moscow region, respectively. The high SMN2 duplication frequency in Udmurts may explain why the SMN1 heterozygous carriage frequency in this population was overestimated in earlier PCR-RFLP analyses.

[Diagnostics of keratitis-ichthyosis-deafness syndrome (KID- syndrome)].

The combination of pre-lingual and sensorinerual deafness with skin hyperkeratinization is a relatively rare pathology. Only 11 families affected by this disorder were described in the literature during the last 30 years (from 1975 to 2002). To date, there are no more than 50 cases of this condition known in the world. Modern molecular methods revealed in all such patients a mutation in the GJB2 gene as the primary cause of the disease. We studied a 4 year-old girl with bilateral congenital grade IV sensorineural deafness. Her unusual appearance drew attention aas early as the primary examination; the patient had the deep-set eyes and dry skin over the entire body, she presented with hypotrichosis of the scalp, thin and light-blond hair. Analysis of the nucleotide sequence of the GJB2 gene revealed the substitution of guanine-148 by adenine that led to D50N amino acid substitution. This dominant mutation proved to be the cause of keratitis-ichthyosis-deafness syndrome (KID-syndrome). A review of the literature concerning molecular diagnostics and clinical features of this syndrome is presented. The results of molecular-genetic investigations provided the data on pathogenesis of different variants of sensorineural deafness and the associated genotype-phenotype relationships that may be used as a basis for the further development of the methods for the prevention and treatment of KID-syndrome.