| Abstract [eng] |
Retrospective PCR Analysis of Dried Blood Spots (DBS) to Identify Congenital Cytomegalovirus Infection as a Cause of Pediatric Sensorineural Hearing Loss Congenital cytomegalovirus infection (cCMV) has high importance among all intra-uterine transmission of infections, as it is the most common cause of non-genetic sensorineural hearing loss (SNHL) and other lesions in children. Timely diagnosis might be a successful way to mitigate the consequences cCMV infection and prevent progression of lesions by treatment. However, most cases of maternal and fetal CMV infections are clinically silent and it remains problematic. The aim of the Thesis. To use dried blood spots (DBS) as a sample for retrospective detection of CMV, as congenital infection is a cause of non-genetic SNHL in children, and to compare anamnesis data of different SNHL etiologies. Objectives. To test DBS for possible CMV viraemia and compare the results obtained with the incidence rate of congenital CMV infection in the reports by Lithaunian Infectious Diseases and AIDS Center in 2003 – 2016; to assess the correspondence with age recommendations for the diagnosis of infant deafness and cochlear implantation (CI) in the group where cCMV is likely to be the primary cause of SNHL and to compare the results with other SNHL etiology groups ; to compare the efficacy of CI in the group where cCMV is likely to be the primary cause of SNHL with other SNHL etiology groups, based on Speech Intelligibility Rating (SIR), Category of Auditory Performance (CAP) scores. Methods. The data of 113 children with prelingual SNHL who underwent cochlear implantation (CI) was analyzed. DNA extraction from dried blood spots (DBS) was performed. CMV DNA detection performed by real time PCR, the results were evaluated qualitatively due to the unknown actual dry blood spot volume. Additionally, patients medical records were analysed. Other possible etiological factors which caused SNHL were identified by other researches. Results. From 113 DBS samples tested by real time PCR, 14 (12,4%) were positive for CMV DNA, 12 (10,6%) of them were associated with prenatal CMV infection as a SNHL. A retrospective analysis has shown that newborns with CMV viremia remain unidentified, and therefore potential incidences of cCMV infection are not recorded in ULAC morbidity reports. For the group where cCMV is likely to be the primary cause of SNHL, the diagnosis of the hearing impairment did not comply with the Joint Committee on Infant Hearing (JCIH) recommendations and was not performed before 3 months of age and was carried out later than that in the GJB2 gene mutation group. Hearing rehabilitation with CI was performed in a timely manner, but later than in the group with the GJB2 gene mutation. For the group where cCMV is likely to be the primary cause of SNHL, CI did not help to achieve the highest CAP and SIR scores, which were lower compared to GJB2 gene mutation group. |
