Association of vitamin D receptor polymorphisms and type 1 diabetes susceptibility in children: a meta-analysis

BACKGROUND

There have been studies focused on FokI, BsmI, ApaI and TaqI polymorphisms of the vitamin D receptor (VDR) gene and susceptibility to type 1 diabetes mellitus with controversial results.

METHODS

This present study is a meta-analysis investigating the association between FokI, ApaI, TaqI and BsmI polymorphisms of VDR gene and type 1 DM in children. A literature search was performed using Medline, EMBASE, Cochrane and PubMed. Any study was considered eligible for inclusion if at least one of FokI, ApaI, TaqI and BsmI polymorphisms was determined, and outcome was type 1 DM at pediatric age.

RESULTS

A total of 9 studies comprising 1053 patients and 1017 controls met the study inclusion criteria. The pooled odds ratios (ORs) of the FokI, ApaI, TaqI and BsmI polymorphisms were combined and calculated. Forest plots and funnel plots of the OR value distributions were drawn. Our meta-analysis has demonstrated statistically significant associations between DM1 and VDR genotypes, BsmIBB (P < 0.05), BsmIBb, (P < 0.05), BsmIbb (P < 0.05), TaqITT (P < 0.05) and TaqItt (P < 0.05) in children.

CONCLUSION

The results indicated that BsmIBB, BsmIBb and TaqItt polymorphisms were associated with an increased risk of type 1 DM, whereas BsmIbb and TaqITT had protective effect for type 1 DM in children.

The association of residential mold exposure and adenotonsillar hypertrophy in children living in damp environments

BACKGROUND

There are many consequences of mold exposure related to respiratory system health of children This retrospective cohort study aims to find the association between adenoid hypertrophy and mold exposure in children living in damp environments.

METHODS

Children with history of recurrent respiratory tract infections were enrolled in the study between June 2012 and June 2013 and were followed up for adenoid hypertrophy from June 2013 to June 2016. One hundred and forty two children were residents of moldy houses and 242 were living in normal houses. Skin prick test results for 60 common allergens, vitamin D levels, IgE levels, age, presence of comorbidities such as urticaria, atopic dermatitis, allergic conjunctivitis, allergic rhinitis, asthma, frequency of upper respiratory tract infections and lower respiratory tract infections, were evaluated in both groups.

RESULTS

A total of 384 children (mean age ± standard deviation = 53.37 ± 36 months; 198 males and 186 females) were included. The children were classified into 2 groups (1)Children living normal houses (n = 242) (2); Children living in damp houses (n = 142) according to mold exposure. Children with adenoid hypertrophy (p < 0,001) and higher IgE levels (p < 0,001) were more common in mold exposed group. Lower respiratory tract infections were more common in children with mold exposure (p < 0,05). Bivariate correlation analysis showed no significant association between IgE levels and adenoid hypertrophy. Multiple linear regression analysis was performed to evaluate IgE levels, vitamin D levels, and presence of adenoid as independent variables; age as dependent variable among two groups and was found statistically significant (p < 0,001). Dermatophagoid sensitive group living in damp houses had a significant increase in adenoid hypertrophy (p = 0,01). Housedustmite sensitive children with recurrent lower respiratory tract infection and upper respiratory tract infection were mainly residents of damp houses (p < 0,001). Allergic comorbidities were significantly more in damp environment group (p < 0,001), but there was no significant increase in any of the subgroups.

CONCLUSIONS

Children with mold exposure had significantly increased adenoid hypertrophy regardless of their atopic nature, however, they may have become more sensitized due to other environmental triggers and genetic factors. In damp environments, sensitization to dermatophagoids, was significantly increased in children with adenoid hypertrophy. During the period of infancy, when children were mostly vitamin D supplemented, they were not sensitized and had normal adenoids. As children with recurrent respiratory tract infections grow, they tend to have lower vitamin D levels, become more atopic and tend to have adenoid hypertrophy.