Chronic and recurrent otitis media: a genome scan for susceptibility loci

Hearing screening and middle ear measures in American Indian infants and toddlers

American Indian children have three times the rate of otitis media compared to the general population, yet prospective cohort studies of OME and hearing loss have not been previously reported in American Indian infants. Between 1997 and 2003, a cohort of 421 infants was enrolled at birth from Minnesota American Indian reservations and an urban clinic and followed to age 2 years. This study reports OAE hearing screening results related to OME diagnoses, as well as risk for recurrent hearing screening failure and OME in American Indian infants and children.

METHODS

Infants were prospectively assessed at regular intervals with pneumatic otoscopy, distortion product otoacoustic emissions, and tympanometry by nurses who were trained in all procedures and validated on pneumatic otoscopy.

RESULTS

In the newborn period, 23.5% of infants failed hearing screening in at least one ear. Hearing screening failures increased to 29.9% from 2 to 5 months of age. Technical fail results due to excessive noise occurred frequently in infants 6-24 months of age, making interpretation of true pass and fail rates questionable in older infants. OAE test result was associated with OM diagnosis, and this relationship strengthened with age, with the strongest association above 6 months of age.

CONCLUSIONS

A high rate of hearing screening failures occurred among American Indian infants in the first 5 months of age, and was significantly associated with a correspondingly high rate of otitis media. Only one infant out of 366 was identified with sensorineural hearing loss, thus essentially all of the hearing screening failures reflected either a middle ear origin or other temporary problems. OAE screening provided a valuable hearing screening measure in this population at high risk for recurrent otitis media, but due to excessive noise in infants 6 months and older, practical use of OAE screening is limited. Use of behavioral assessment is needed after 6 months of age, when high rates of OME persist in this population. Increased efforts to develop public and medical education, as well as screening, diagnosis and treatment programs are needed to detect and decrease recurrent OME in American Indian infants and children.

Mutation at the Evi1 locus in Junbo mice causes susceptibility to otitis media

Otitis media (OM), inflammation of the middle ear, remains the most common cause of hearing impairment in children. It is also the most common cause of surgery in children in the developed world. There is evidence from studies of the human population and mouse models that there is a significant genetic component predisposing to OM, yet nothing is known about the underlying genetic pathways involved in humans. We identified an N-ethyl-N-nitrosourea-induced dominant mouse mutant Junbo with hearing loss due to chronic suppurative OM and otorrhea. This develops from acute OM that arises spontaneously in the postnatal period, with the age of onset and early severity dependent on the microbiological status of the mice and their air quality. We have identified the causal mutation, a missense change in the C-terminal zinc finger region of the transcription factor Evi1. This protein is expressed in middle ear basal epithelial cells, fibroblasts, and neutrophil leukocytes at postnatal day 13 and 21 when inflammatory changes are underway. The identification and characterization of the Junbo mutant elaborates a novel role for Evi1 in mammalian disease and implicates a new pathway in genetic predisposition to OM.

Otitis media (OM), inflammation of the middle ear, is the most common cause of deafness in children. Although acute episodes of OM in children are associated with middle ear infections, in a substantial portion of cases recurrent episodes of OM, or a chronic suppurative OM, will develop. There is evidence from genetic studies of human families that there is a significant genetic component contributing to the development of recurrent and chronic forms of OM. However, the genes involved have not been identified. The authors have identified and characterized mouse mutants that demonstrate chronic OM as a route to identifying genes involved with OM. This study describes one mutant, Junbo, which shares many features with human OM. Junbo develops an acute OM following birth that subsequently develops into a chronic suppurative form of OM. Junbo carries a mutation in the transcription factor gene, Evi1. Evi1 is expressed in a variety of cell types in the middle ear lining when inflammatory changes are underway. The identification of the Junbo mutation implicates a new gene involved in predisposition to OM.

Early otitis media among Minnesota American Indians: the Little Ears Study

OBJECTIVES

We examined relationships between otitis media risk factors, sociodemographic characteristics, and maternal knowledge and attitudes and early onset of otitis media.

METHODS

Pregnant women from Minnesota American Indian reservations and an urban clinic were enrolled in our study between 1998 and 2001. Follow-up was performed on enrollees' infants until the children were 2 years old. Research nurses collected data by ear examination, from interviews and questionnaires given to enrolled mothers, and otitis media episodes that were abstracted from medical records.

RESULTS

Sixty-three percent of infants had experienced an otitis media episode by 6 months of age. Logistic regression analyses showed that maternal otitis media history, infant history of upper respiratory infection, and compliance with study visits were significantly related to early otitis media onset. Although high percentages of infants were exposed to cigarette smoke and other children and were formula fed, these factors were not related to otitis media. Mothers' prenatal awareness of otitis media risks associated with environmental tobacco smoke exposure and formula feeding did not predict their postpartum behaviors.

CONCLUSIONS

We found that infant history of upper respiratory infection and maternal otitis media history are risk factors for early otitis media in American Indian infants. Mothers' prepartum knowledge and attitudes regarding otitis media did not predict their postpartum avoidance of risk behaviors.

Association of proinflammatory cytokine gene polymorphisms with susceptibility to otitis media

OBJECTIVE

Susceptibility to otitis media results from complex interactions among genetic factors of the host, exposure to pathogens, and environmental influences. The objective of this study was to study the role of single-nucleotide polymorphisms of regulatory elements of proinflammatory cytokine genes tumor necrosis factor-alpha(-308), interleukin-1beta(+3953), and interleukin-6(-174), in susceptibility to recurrent otitis media in childhood.

METHODS

A total of 505 children (296 otitis media susceptible, 209 nonsusceptible as control) were enrolled at 2 sites (Texas and Kentucky). DNA of the children was studied for specific single-nucleotide polymorphisms by restriction fragment length polymorphism assay and confirmed by gene sequencing.

RESULTS

In the overall study group, tumor necrosis factor-alpha(-308) and interleukin-6(-174) heterozygous or homozygous polymorphisms (high cytokine-producing genotypes) were significantly associated with otitis media susceptibility. The same association was found in a match-paired subgroup of 384 subjects. In the overall study group, there was a significant step-wise increase in otitis media susceptibility with increasing number of concomitant polymorphic genotypes. Simultaneous combination of tumor necrosis factor-alpha(-308) and interleukin-6(-174) polymorphisms further increased the risk for otitis media susceptibility. These 2 polymorphic genotypes also were associated with the increased risk for tympanostomy tube placement. Children who had tumor necrosis factor-alpha(-308) polymorphism and were breastfed for <1 month or exposed to cigarette smoke were more likely to be otitis media susceptible.

CONCLUSIONS

Our data suggest that tumor necrosis factor-alpha(-308) and interleukin-6(-174) polymorphisms are associated with increased risk for otitis media susceptibility and placement of tympanostomy tubes. Environmental factors such as breastfeeding may modify the risk for otitis media susceptibility in polymorphic individuals.

Adenoidectomy and tympanostomy tubes in the management of otitis media

Otitis media is one of the most common childhood infections and the most frequent cause for antibiotic prescriptions in children. As respiratory infections are also associated with childhood asthma, children with recurrent otitis media or with persistent middle-ear effusion are also at an increased risk for developing asthma, which should be appreciated when a child with middle-ear disease is evaluated. The first choice of surgery in chronic middle-ear inflammatory disease is the insertion of tympanostomy tubes. It is warranted when the middle-ear effusion has lasted for 3 or more months. When chronic adenoid infection is suspected, adenoidectomy may be beneficial in treating otitis media in children who are older than 4 years of age and who have previously undergone tympanostomy-tube insertion.

A mutation in the F-box gene, Fbxo11, causes otitis media in the Jeff mouse

Otitis media (OM), inflammation of the middle ear, is the most common cause of hearing impairment and surgery in children. Recurrent and chronic forms of OM are known to have a strong genetic component, but nothing is known of the underlying genes involved in the human population. We have previously identified a novel semi-dominant mouse mutant, Jeff, in which the heterozygotes develop chronic suppurative OM (Hardisty, R.E., Erven, A., Logan, K., Morse, S., Guionaud, S., Sancho-Oliver, S., Hunter, A.J., Brown, S.D. and Steel, K.P. (2003) The deaf mouse mutant Jeff (Jf) is a single gene model of otitis media. J. Assoc. Res. Otolaryngol., 4, 130-138.) and represent a model for chronic forms of OM in humans. We demonstrate here that Jeff carries a mutation in an F-box gene, Fbxo11. Fbxo11 is expressed in epithelial cells of the middle ears from late embryonic stages through to day 13 of postnatal life. In contrast to Jeff heterozygotes, Jeff homozygotes show cleft palate, facial clefting and perinatal lethality. We have also isolated and characterized an additional hypomorphic mutant allele, Mutt. Mutt heterozygotes do not develop OM but Mutt homozygotes also show facial clefting and cleft palate abnormalities. FBXO11 is one of the first molecules to be identified, contributing to the genetic aetiology of OM. In addition, the recessive effects of mutant alleles of Fbxo11 identify the gene as an important candidate for cleft palate studies in the human population.

Recurrent otitis media and tonsillitis: common disease predisposition

OBJECTIVE

To estimate the relative contribution of genetic and environmental effects to the association between recurrent otitis media and recurrent tonsillitis.

METHODS

Self-report questionnaire data from a population-based cohort of 9479 Norwegian twins born from 1967 to 1979. Recurrent otitis media and recurrent tonsillitis were main outcome measures. Structural equation modelling was used to fit alternative biometric models to the twin data and to estimate the relative contribution of genetic and environmental effects to the association between otitis media and tonsillitis.

RESULTS

The lifetime prevalence was 11.7% (95% CI: 11.0-12.3) for recurrent tonsillitis and 11.2% (95% CI 10.5-11.9) for recurrent otitis media. Tetrachoric correlations were greater in monozygotic than in dizygotic twins in both males and females. A model specifying additive genetic effects and individual environmental effects for otitis media and tonsillitis and non-additive genetic effects for tonsillitis yielded the best fit. There was no evidence for sex differences in the genetic source or magnitude of the genetic effects. There was a substantial overlap in genetic factors influencing variation in liability to otitis media and tonsillitis.

CONCLUSION

Common genetic factors contribute substantially to comorbidity between recurrent otitis media and recurrent tonsillitis.

Association of the FBXO11 gene with chronic otitis media with effusion and recurrent otitis media: the Minnesota COME/ROM Family Study

OBJECTIVE

The FBXO11 gene is the human homologue of the gene mutated in the novel deaf mouse mutant jeff (Jf), a single gene model of otitis media. We have evaluated single nucleotide polymorphisms (SNPs) in the FBXO11 gene for association with chronic otitis media with effusion/recurrent otitis media (COME/ROM).

DESIGN

A total of 13 SNPs were genotyped across the 98.7 kilobases of genomic DNA encompassing FBXO11. Data were analyzed for single SNP association using generalized estimating equations, and haplotypes were evaluated using Pedigree Disequilibrium Test methods.

PATIENTS

The Minnesota COME/ROM Family Study, a group of 142 families (619 subjects) with multiple affected individuals with COME/ROM.

MAIN OUTCOME MEASURES

Genetic association of COME/ROM with polymorphisms in FBXO11.

RESULTS

The FBXO11 SNPs are contained in a single linkage disequilibrium haplotype block. Ten of the 13 SNPs were sufficiently polymorphic in the sample to permit analysis. In univariate genetic analysis, 1 reference SNP (hereinafter rs) (rs2134056) showed nominal evidence of association to COME/ROM (P = .02), and 2 SNPs approached significance (rs2020911, P = .06; rs3136367, P = .09). In multivariable analyses, including known risk factors for COME/ROM (sex, exposure to smoking, attending day care centers, no prior breastfeeding, and having allergies), the evidence of independent association was reduced for each SNP (eg, rs2134056, from P = .02 to P = .08). In subsequent analyses using the Pedigree Disequilibrium Test, the association of FBXO11 SNP rs2134056 (P = .06) with COME/ROM was confirmed. Incorporating multiple SNPs in 2- and 3-locus SNP haplotypes, those haplotypes containing rs2134056 also exhibited evidence of association of FBXO11 and COME/ROM (P values ranging from .03 to .10).

CONCLUSION

We have observed evidence consistent with an association between polymorphisms in FBXO11, the human homologue of the Jeff mouse model gene, and COME/ROM.

Association of surfactant protein A polymorphisms with otitis media in infants at risk for asthma

Background

Otitis media is one of the most common infections of early childhood. Surfactant protein A functions as part of the innate immune response, which plays an important role in preventing infections early in life. This prospective study utilized a candidate gene approach to evaluate the association between polymorphisms in loci encoding SP-A and risk of otitis media during the first year of life among a cohort of infants at risk for developing asthma.

Methods

Between September 1996 and December 1998, women were invited to participate if they had at least one other child with physician-diagnosed asthma. Each mother was given a standardized questionnaire within 4 months of her infant's birth. Infant respiratory symptoms were collected during quarterly telephone interviews at 6, 9 and 12 months of age. Genotyping was done on 355 infants for whom whole blood and complete otitis media data were available.

Results

Polymorphisms at codons 19, 62, and 133 in SP-A1, and 223 in SP-A2 were associated with race/ethnicity. In logistic regression models incorporating estimates of uncertainty in haplotype assignment, the 6A⁴/1A⁵haplotype was protective for otitis media among white infants in our study population (OR 0.23; 95% CI 0.07,0.73).

Conclusion

These results indicate that polymorphisms within SP-A loci may be associated with otitis media in white infants. Larger confirmatory studies in all ethnic groups are warranted.

Recent Developments in the Treatment of Otitis Media with Effusion

The management of otitis media with effusion (OME) has received much attention recently as a result of, among other factors, the development of resistant bacteria and the finding of less long-term impact of middle-ear effusion (MEE) on development than previously believed. Guidelines have recently been published for the management of OME promoting more accurate diagnosis, particularly distinguishing acute otitis media from OME, and recommending the 'judicious' use of antibacterials. Today, more emphasis is being placed on prevention of disease by reducing risk factors and the development of vaccines. The identification of susceptibility genes may lead to better understanding of the pathogenesis of otitis media, which in turn may lead to the development of more innovative and satisfactory methods for prevention and treatment.