Etiology of severe sensorineural hearing loss in children: independent impact of congenital cytomegalovirus infection and GJB2 mutations.
BACKGROUND
Sensorineural hearing loss (SNHL) is the most common congenital disease. Longitudinal studies of infants with congenital cytomegalovirus (CMV) infection have demonstrated an association between CMV and SNHL. However, because of the lack of suitable neonatally collected specimens, the proportion of CMV-associated SNHL has not been defined, nor has the relationship between CMV and the major genetic causes of SNHL, such as mutations in the GJB2 gene.


METHODS
Sixty-seven children with severe SNHL were analyzed for CMV and human herpesvirus 6 (HHV-6) infections and for GJB2 mutations. DNA specimens were prepared from dried umbilical cords, which are available for everyone born in Japan. Four children with typical symptomatic infection at birth served as positive control subjects.


RESULTS
Congenital CMV infection and GJB2 mutations were identified in 15% and 24% of the patients, respectively. HHV-6 was not detected. All children with CMV-associated cases developed SNHL before they were 2 years old. Most children with CMV-associated SNHL had no obvious clinical abnormality at birth, and their viral loads were lower than those of symptomatic children.


CONCLUSIONS
Congenital CMV infection is an important cause of severe SNHL, and it has an incidence comparable to that of GJB2-associated SNHL.
Ogawa
Hiroshi
H
National Institute of Infectious Diseases, Tokyo, 162-8640, Japan.
Suzutani
Tatsuo
T
Baba
Yohko
Y
Koyano
Shin
S
Nozawa
Naoki
N
Ishibashi
Kei
K
Fujieda
Kenji
K
Inoue
Naoki
N
Omori
Koichi
K
D001483:Base Sequence; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D003587:Cytomegalovirus / Q000302:isolation & purification*; D003586:Cytomegalovirus Infections / Q000453:epidemiology*; D004247:DNA / Q000097:blood / Q000235:genetics / Q000302:isolation & purification; D017931:DNA Primers; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D020022:Genetic Predisposition to Disease; D006319:Hearing Loss, Sensorineural / Q000209:etiology* / Q000235:genetics; D006320:Hearing Tests; D015654:Herpesvirus 6, Human / Q000302:isolation & purification; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009154:Mutation
D017630:Connexins; D017931:DNA Primers; C000607042:GJB2 protein, human; D000072259:Connexin 26; D004247:DNA