Iatrogenic influences on the heritability of childhood tonsillectomy: cohort differences in twin concordance

Adenotonsillectomy for paediatric sleep disordered breathing in Australia and New Zealand

AIMS

To review the contributions of Australian and New Zealand research on adenotonsillectomy for the treatment of symptoms of obstructed breathing during sleep (sleep disordered breathing, SDB) in children.

METHODS

A search of the scientific literature was conducted using the MEDLINE (Ovid), PubMed and Scopus databases in August 2020. The following search string was used: (tonsillectomy OR adenoidectomy OR adenotonsillectomy) AND (paediatric OR child) AND (Australia OR New Zealand). A focused internet search was additionally conducted on Google to identify grey literature.

RESULTS

Researchers from Australia and New Zealand have made important contributions to the understanding and improvement of adenotonsillectomy (AT), including its epidemiology, cost, surgical techniques and peri-operative safety. Rates of AT have fluctuated over the years, becoming the most common paediatric surgery today, with SDB becoming the most common indication. Research in Australia and New Zealand has also focussed on the impact of AT on quality of life, and behaviour, neurocognition and cardiovascular sequelae.

CONCLUSIONS

Australian and New Zealand researchers have played a significant role in understanding the epidemiology and improving the safety of AT. There are promising directions in research still to come, including better understanding of the reasons for geographical variation in surgery rates, developing more efficient pre-operative risk assessment tools and alternative treatment options for mild OSA.

Familial and Environmental Risk Predisposition in Tonsillectomy: A Case-Control Study

Background

Tonsillectomy is one of the most commonly performed procedures among children and it is the gold standard management to reduce episodes of tonsillitis and obstructive symptoms. Many studies showed a significantly higher incidence of previous tonsillectomy in the parents and siblings. This study investigated the influence of familial and environmental trends in tonsillectomy.

Methods

Retrospectively, we identified those patients who underwent tonsillectomy (the case group). Also, a control group of participants attending the hospital as visitors who had not undergone tonsillectomy was collected. Both groups are compared using the proper statistical tests.

Results

This study included 1,232 participants; 615 underwent tonsillectomy (cases) and 617 did not (controls). It was found that paternal and maternal history of tonsillectomy, childhood asthma, and daycare attendance are independent factors influencing tonsillectomy in the offspring. Of about 85.4% of fathers who underwent tonsillectomy their children will also have tonsillectomy. Also, regarding the maternal history, 72.5% of offspring will have tonsillectomy if the mothers underwent the procedure.

Conclusion

This study reveals that genetic predisposition factors may have a role for tonsillectomy and its underlying causative indications. Also, it highlights the importance of asthma control in children. Moreover, the role of ethnicity may be minimal due to the similar trend of this study with other studies. Further studies and prospective research are recommended.

An analysis of the histomorphometric and clinical significance of mucosal biofilm in tonsil tissue of the children with a history of recurrent/chronic tonsillitis in both the mother and father

PURPOSE

The aim of this study is to analyse the histomorphometric and clinical features of the mucosal biofilm in tonsil tissue of children with a history of recurrent/chronic tonsillitis in both the mother and father.

METHODS

This study enrolled 82 children (between 3 and 14 years of age). These children were divided into two main groups according to the present of recurrent/chronic tonsillitis. Patients in group 1 were divided into four subgroups (A, B, C, D) according to the history of recurrent/chronic tonsillitis in mother and/or father. 30 patients in group 1 were underwent tonsillectomy and the 52 patients in control group (2) have not had history of recurrent/chronic tonsillitis. To that end, among children with a history of recurrent/chronic tonsillitis certain changes in the volume and thickness of mucosal biofilm in tonsil tissue have been exhibited with respect to it is histomorphometric and clinical significance.

RESULTS

The children with a parental history of recurrent/chronic tonsillitis in group A, an increase in the thickness and volume of mucosal biofilm samples was detected according to the other subgroups (B, C, D). Parents history of group A patients statistically significant differences were detected with respect to halitosis symptoms, attack age of the first tonsillitis and resistant fever despite antibiotic treatment for children under the age of 3 years.

CONCLUSIONS

This study showed that children under the age of 3 years of age with a history of recurrent/chronic tonsillitis in both the mother and father, halitosis symptoms, attack age of the first tonsillitis and resistant fever despite antibiotic treatment are collectively linked.

Familial aggregation of tonsillectomy in early childhood and adolescence

Background

The tonsils are immunological gatekeepers against pathogens. Immunological response to tonsillitis may vary clinically from no enlargement of the tonsils to nearly obstructive conditions. In this investigation, we studied the familial aggregation of tonsillectomy, as an indicator of the extent to which tonsillar immune responses to infections might be genetically controlled.

Methods

Data on kinship relations and vital status from the Danish Civil Registration System were used to establish a cohort of Danes with relatives born since 1977. Tonsillectomies in all hospitals and clinics from 1977 to 2013 were identified in national registers together with the indication for tonsillectomy. Rate ratios (RRs) for tonsillectomy >1 year after tonsillectomy in specific types of relatives (first to fourth degree) were estimated in Poisson regression models with adjustment for calendar period, sex, age, and total number of specified relatives.

Results

A cohort of 2.4 million persons was followed for 44,100,697 million person-years (mean 18.4 years/person), and included 148,190 tonsillectomies. RRs of tonsillectomy were consistently higher when the relatedness and the number of tonsillectomized relatives were higher. RRs were similar in boys and girls, but were larger in early childhood. Additional analyses suggested that this relatively higher RR at younger ages was due to a larger influence of shared environment at younger ages, whereas the genetic influence was similar at all ages. Results were similar for tonsillectomies performed strictly due to tonsillitis.

Conclusions

Genetic factors appear to predispose to severe tonsillitis underlying tonsillectomies, regardless of age and sex. Further studies are needed to understand how genes regulate the tonsils' immune response against infections.

Genetic and Environmental Contributions to Variance in Age at First Sexual Intercourse

Little is known about the relative importance of genetic and environmental factors as determinants of age at first sexual intercourse In this study, subjects were 5,080 individuals from the Australian Twin Registry (3,310 females, I 770 males, age range 27-70 years, median 40 years) who completed a semistructured interview by telephone in 1992-1993 Self-reported age at first intercourse correlated higher for identical (monozygotic) twins than for nonidentical (dizygotic) twins Structural equation model fitting found that the genetic contribution to variance was considerably greater among twins aged 40 years or less (72% for males and 49% for females) than for those aged from 41 to 70 years (0% for males and 32% for females) Among the older cohort, there was evidence that somewhat different aspects of the shared social environment influenced age at onset in males and females In a more laissez-faire social climate in recent decades, it is likely that biological and psychological characteristics that are partly under genetic control significantly influence the age at which a person commences sexual activity

Sibling risk of pediatric obstructive sleep apnea syndrome and adenotonsillar hypertrophy

OBJECTIVES

To estimate sibling risk of hospitalization for children with sleep disordered breathing (SDB), diagnosed with (1) obstructive sleep apnea syndrome (OSAS), or (2) adenotonsillar hypertrophy in the total Swedish population.

DESIGN, SETTING, AND PARTICIPANTS

Using the MigMed database at the Karolinska Institute, we divided the population of Sweden aged 0-18 years into sibling groups based on a shared mother and father and presence of a primary hospital diagnosis of OSAS or adenotonsillar hypertrophy for each individual born between 1978 and 1986, during the follow-up period 1997-2004. Individuals with at least one affected sibling were identified and the incidence rates were computed, using standardized incidence ratios (SIRs) with 95% confidence intervals (CIs). Reference groups were boys and girls with unaffected siblings of 2 or more.

RESULTS

After accounting for socioeconomic status, age, and geographic region, boys with at least one sibling with OSAS had an increased risk of having OSAS (SIR, 33.2; 95% CI, 16.5-64.8), and in girls the SIR was 40.5 (19.4-81.4). For hypertrophy of the tonsils or hypertrophy of the adenoids and tonsils the corresponding SIRs were 4.53 (3.0-6.8) for boys and 4.94 (3.3-7.4) for girls.

CONCLUSIONS

The study indicate an increased sibling risk of sleep disordered breathing in children, which may be due to heritable genes and/or shared environment such as increased awareness among family members or referring doctors. Caregivers should ask parents if siblings have similar symptoms, and thus offer them early treatment.

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.

Genetics of educational attainment in Australian twins: sex differences and secular changes

The relative effects of genetic and environmental factors in producing individual differences in educational achievement are compared across women and men and over birth cohorts. In a large sample of Australian twin pairs, the heritability of self-reported educational attainment did not vary among women and men born before and after 1950. In a "psychometric" model of twin resemblance, based on separate self-reports in 1981 and 1989, genetic factors explained 57% of the stable variance in educational achievement, while environmental factors shared by twins accounted for 24% of the variance. Corrections for phenotypic assortative mating for educational level, however, suggested that estimated common-environmental effects could be entirely explained by the correlation between additive genetic values for mates. Taking this into account, heritability "true" educational attainment in Australia may be as high as 82% with the remaining variation being due to individual environments or experiences. Unlike previous studies in Scandinavian countries, results in Australia suggest that factors influencing educational success are comparable between women and men and for individuals born at different points during this century.

Pathways to hysterectomy: insights from longitudinal twin research

OBJECTIVE

We hypothesized that genetic influences act on "liability" to hysterectomy, that secular influences might differentially affect relative importance of genetic and environmental influences, and that the sources of genetic influences could be identified from reported risk factors.

STUDY DESIGN

Hysterectomy data from an Australia-wide volunteer sample of female adult monozygotic and dizygotic twins are reported. In 1980 through 1982 a mailed questionnaire was completed by 1232 monozygotic female twin pairs and 751 dizygotic female twin pairs (3966 women) from the Australian Twin Register (wave 1). The same twins were surveyed by questionnaire 8 years later (wave 2).

RESULTS

A total of 366 had undergone hysterectomy by wave 1 and a further 198 at wave 2. The twin-pair correlations for liability to hysterectomy at wave 1 (0.61 +/- 0.06 for monozygotic and 0.20 +/- 0.11 for dizygotic) and wave 2 (0.65 +/- 0.05 for monozygotic and 0.32 +/- 0.09 for monozygotic) indicated a substantial genetic contribution. Reported risk factors accounted for only 15% of total variance.

CONCLUSION

Genetic influences on liability to hysterectomy were substantial and stable across birth cohorts, but the important sources of genetic influence on liability to hysterectomy are yet to be identified.