Objective: To discuss and analyze the feasibility and strategy for perform the newborn gene screening in the process of newborn hearing screening in order to supply the defects or limitation in the hearing screening.
Methods: Four hundreds and sixty newborn babies from December 2006 to April 2007 accepted the simultaneous hearing and gene screening. Otoacoustic emission (OAE) was used for the first step hearing screening and OAE combined with auto auditory brainstem response (AABR) detection for the second step screening. Newborn genetic disease screening cards were used for collecting the blood spot from the umbilical cord within the moment of newborn. The cards could be directly performed the polymerase chain reaction (PCR) for screening the mitochondrial 12SrRNA 1555G and GJB2 as well as SLC26A4 genes mutations. The restriction enzyme Alw26I was used to recognize the point mutation of 12SrRNA A1555G. The samples with the possible 12SrRNA A1555G mutation were then sequenced to verify. The PCR products from the GJB2 coding region and SLC26A4 IVS7-2A > G hot spot region were sequenced directly. The software of DNAStar was used to analysis the sequence.
Results: The first step of hearing screening of 460 newborn babies showed " refer" on the left ear of nine babies and on the right ear of three babies. Seven showed "refer" on bilateral with the the total of babies 19. After 42 days, they accepted the second step for hearing screening. 16 of the 19 were showed "pass" with OAE and AABR. One baby showed "pass" on the left ear, "refer" on the right ear with the OAE detection but bilateral "pass" with AABR. Two babies failed to accept the re-examination. The newborn gene screening showed five of the 460 babies had the positive response on the A1555G restriction enzyme assay. Of the five babies, one was proved to be the 12SrRNA A1555G mutation and three were the C1556T mutations and one sequence was normal. For the SLC26A4 gene screening, five were the heterozygote of IVS7-2A > G mutation were found and one was carrier the polymorphism of IVS7-18T > G and another was IVS6-62_63insGT heterozygote carrier. For the GJB2 gene screening, eight were 235delC heterozygote carriers, four were G109A heterozygote carriers. All the gene screening found 23 newborn babies of the 460 harbored the changes in the three genes. Of those, one was the 12SrRNA A1555G. pathogenic mutation and 13 were pathogenic heterozygote carriers, nine were the polymorphisms. It was worth to pay more attentions that A1555G mutation was found in the baby whose hearing screening was "pass" in the hearing screening as well as the 13 heterozygote carrier for GJB2 and SLC26A4 gene.
Conclusions: It might be one of the powerful strategy for adding the concept of newborn gene screening into the hearing screening for the purpose of early diagnosis and discovery the prelingual or late-onset or the high risk as well as the pathogenic carriers. On the basis of the research progress, it was necessary to develop the national newborn gene screening into the process of newborn hearing screening.