Extensive screening and study of deafness genes from the newborn cord blood

Abstract

Objective To study the mutation rate of hereditary deafness genes found in the newborn babies and to explore the feasibility of routine screening of congenital deafness for the newborns. Method The cord blood were taken to test four common deafness genes using gene chip technology in newborn infants born in our Hospital from May 2015 to May 2017 and screening of hearing was performed 48 hours after birth. χ2 test was used to analyze the results of gene screening and the hearing screening data obtained after 42 days. Result A total of 2 615 newborns were enrolled in the study and 2 455 cases passed the hearing screening test 48 hours after birth (the passing rate was 93.9%). 143 cases passed the hearing screening after 42 days with the passing rate of 99.3%. The mutation of deafness gene from the newborn′s cord blood was detected in 107 cases with the rate of 4.1%. 96 of 107 infants with deafness gene mutations passed the hearing screening (89.7%). While in infants without this mutation, 2 502 cases passed the hearing screening (99.8%, 2 502/2 508). The rate of hearing defects in children with deafness gene mutation was significantly higher than those without this gene mutation, and the difference was statistically significant (χ2=160.199, P<0.001). Of the 107 cases, the most common mutation was GJB2 (49 cases, 45.8%), followed by SLC26A4 (37 cases, 34.6%) and mtDNA 12SrRNA (13 cases, 12.1%), while the GJB3 was the least (8 cases, 7.5%). 6 cases were diagnosed the neonate hearing loss at 3 months in 17 newborns who failed to pass repeat screening test 42 days after birth. Among them, hearing loss was caused by the mutation in 5 cases. Conclusion The main mutated genes in children with deafness were GJB2 and SLC26A4 in this study. The combination of hearing screening of newborns and gene test is clinically feasible. The deafness genes in the normal hearing carriers can be detected in time. It is of great advantage for early intervention and treament of the infants early. Key words: Genetic testing; Neonatal screening; Hearing tests; Fetal blood; Deafness genes