The problem of diagnostics of congenital hearing impairment has acquired special importance in the light of new possibilities for the early rehabilitation of the patients presenting with this condition. The implementation of the programs of universal audiological screening into the clinical practice of Russia and many other countries made it possible to significantly reducethe time necessary to confirm congenital impairment of hearing and begin the rehabilitative treatment. The present paper was designed to analyze the international experience with the implementation of the programs of universal audiological screening of the newborn infants as exemplified by such countries as Great Britain, USA, Germany, and Poland. The main indicators of the quality and the efficiency of such programs are considered taking into account the results of the epidemiological studies on the prevalence of congenital hearing impairment. A total of 1.8 mln newborn infants were examined in Russia during 2013. The first stage of screening involved 96.7% of the children, and only 2.9% of them remained uncovered by the examination. As many as 5,659 children were found to present with the congenital loss of hearing,with the prevalence of this condition being 3 per 1.000 newborn infants and the prevalence of deafness 0.6 per 1.000. The principal problem to be resolved for the organization of the management of these patients, both in Russia and other countries, remains the enhancement of the availability of comprehensive diagnostic examination and the timelyreferral of the patients to such examination (if appropriate based on the results of the screening). The successful solution of this problem requires personalized recording of the screening data with the use of the commonly accepted medical information systems.

Congenital and early onset bilateral sensorineural hearing loss (SNHL) is mainly caused by mutations in numerous genes. The introduction of universal newborn hearing screening (UNHS) has increased the number of infants with mild, moderate, and moderate-to-severe sensorineural hearing loss (SNHL) detected in the first year of life. We aimed to evaluate the audiological features in patients with mild, moderate, and moderate-to-severe SNHL according to genotype. Audiological and genetic data were analyzed for 251 patients and their relatives with congenital bilateral mild, moderate, and moderate-to-severe SNHL. Hearing loss severity, audiogram profile, interaural symmetry, and dynamics of hearing thresholds were analyzed. In this case, 165 patients had GJB2 gene mutations, 30 patients were identified with STRC mutations, and 16 patients had pathogenic or likely pathogenic USH2A mutations. The presence of at least one GJB2 non-truncating variant in genotype led to less severe hearing impairment. The flat and gently sloping audiogram profiles were mostly revealed in all groups. The follow-up revealed the stability of hearing thresholds. GJB2, STRC, and USH2A pathogenic variants were detected in most patients in our cohort and were congenital in most cases.

Hearing loss is one of the most genetically heterogeneous disorders known. Over 120 genes are reportedly associated with non-syndromic hearing loss (NSHL). To date, in Russia, there have been relatively few studies that apply massive parallel sequencing (MPS) methods to elucidate the genetic factors underlying non-GJB2-related hearing loss cases. The current study is intended to provide an understanding of the mutation spectrum in non-GJB2-related hearing loss in a cohort of Russian sensorineural NSHL patients and establish the best diagnostic algorithm. Genetic testing using an MPS panel, which included 33 NSHL and syndromic hearing loss (SHL) genes that might be misdiagnosed as NSHL genes, was completed on 226 sequentially accrued and unrelated patients. As a result, the molecular basis of deafness was found in 21% of the non-GJB2 NSHL cases. The total contribution pathogenic, and likely pathogenic, variants in the genes studied among all hereditary NSHL Russian patients was 12%. STRC pathogenic and likely pathogenic, variants accounted for 30% of diagnoses in GJB2-negative patients, providing the most common diagnosis. The majority of causative mutations in STRC involved large copy number variants (CNVs) (80%). Among the point mutations, the most common were c.11864G>A (p.Trp3955*) in the USH2A gene, c.2171_2174delTTTG (p.Val724Glyfs*6) in the STRC gene, and c.107A>C (p.His36Pro) and c.1001G>T (p.Gly334Val) in the SLC26A4 gene. Pathogenic variants in genes involved in SHL accounted for almost half of the cases with an established molecular genetic diagnosis, which were 10% of the total cohort of patients with non-GJB2-related hearing loss.

The universal newborn hearing screening (NHS) program was implemented in Russia in 2008 to replace the high-risk newborn hearing screening. More than 95% coverage and significant improvement in early detection and intervention is achieved. Meanwhile, it was shown that current OAE-based hearing screening missed 13% of newborns with genetically ascertained hereditary sensorineural hearing loss (SNHL). The aim of the study is to assess the results of genetic investigation and NHS in a large cohort of Russian children with bilateral SNHL and to study the feasibility of implementation of combined hearing and genetic screening in Russia. Genetic, audiological and NHS data of 1292 pediatric patients with bilateral SNHL born in 2008–2021 were analyzed. GJB2 sequencing was performed for all subjects, 644 patients had pathological GJB2 genotype, 406 of them were homozygous for c.35delG variant. The group of 155 GJB2-negative patients were searched for other SNHL genes, The pathological genotypes were identified at 87 patients. The most frequent genes were STRC (21.8%), USH2A (16.1%), OTOF (8%) and SLC26A4 (6.9%). Children with confirmed genetic etiology passed NHS in 21% of cases. The perspectives of implementation of national comprehensive newborn hearing and genetic screening including whole exome sequencing technologies are discussed.