Cytomegalovirus DNA detection in Guthrie cards: role in the diagnostic work-up of childhood hearing loss.

INTRODUCTION: Cytomegalovirus (CMV) infection is the leading cause of congenital nongenetic sensorineural hearing loss (SNHL) and a major cause of prelingual SNHL that is not present at birth. Polymerase chain reaction (PCR) analysis of dried blood samples on the Guthrie card has been proposed as a sensitive and specific method to screen for congenital CMV infection.

METHODS: Prospectively, consecutive infants who failed universal neonatal hearing screening and children referred for a noncongenital SNHL (NCHL) were included and underwent a standard audiometric and etiologic work-up. DNA was extracted from dried blood spots on neonatal Guthrie cards and amplified by real-time PCR. Data were available for 96 cases.

RESULTS: Mean age of the universal neonatal hearing screening group was 3.8 +/- 2.4 months (n = 41). Auditory brain stem response thresholds were 72.9 +/- 20.2 dB nHL. A CMV-positive PCR was obtained in 4 babies. One test was considered false-positive. This resulted in a 7.3% prevalence of congenital CMV infections.Mean age of the NCHL group was 4.9 +/- 3.2 years (n = 55). Hearing loss was moderate in 37, severe in 5, and profound in 13 children. A CMV-positive PCR was obtained in 4 children (7.3%). Other causes of SNHL were excluded in the PCR positive cases of both study groups.

CONCLUSION: We advocate PCR for CMV DNA detection on Guthrie cards in the etiologic work-up of childhood SNHL and recommend serologic confirmation to exclude false-positive PCR results. 7.3% of SNHL in babies with congenital hearing loss and children with NCHL could be attributed with this technique to congenital CMV infection.