Fig 1.
Flow chart of meta-analysis.
Table 1.
Characteristics of included studies.
Table 2.
Results of meta-analysis.
Fig 2.
Odds ratios of classical presentation of CD at diagnosis with double dose vs. single dose of HLA-DQB1*02.
Patients with a double dose of HLA-DQB1*02 had classical CD more frequently compared to those having a single dose. This association was more prominent in children. Heterogeneity of the groups overall: I2 = 0.0%, p = 0.744; heterogeneity of the subgroup of children: I2 = 0.0%, p = 0.609. CI: confidence interval.
Fig 3.
Odds ratios of classical presentation of CD at diagnosis with double dose vs. zero dose of HLA-DQB1*02.
A significant gene dose effect was detected in the subgroup of children. Heterogeneity of the groups overall: I2 = 40.7%, p = 0.168; heterogeneity of the subgroup of children: I2 = 0.0%, p = 0.747. CI: confidence interval.
Fig 4.
Odds ratios of atrophic histology at diagnosis with double dose vs. single dose of HLA-DQB1*02.
We failed to detect a significant gene dose effect regarding diagnostic histology. Heterogeneity of the groups overall: I2 = 11.8%, p = 0.338; heterogeneity of the subgroup of adults: I2 = 0.0%, p = 0.682; heterogeneity of the subgroup of children: I2 = 71.6%, p = 0.061. CI: confidence interval.
Fig 5.
Odds ratios of atrophic histology at diagnosis with double dose vs. zero dose of HLA-DQB1*02.
Patients with a double dose of the allele were more likely to have villous atrophy at diagnosis than those with a single dose of the allele. Heterogeneity of the groups overall: I2 = 21.3%, p = 0.260; heterogeneity of the subgroup of adults: I2 = 0.0%, p = 0.945; heterogeneity of the subgroup of children: I2 = 0.0%, p = 0.542. CI: confidence interval.
Table 3.
Summary of studies reporting on gene dose effect.
Fig 6.
Summary of risk of bias in individual studies included in meta-analysis.
Green, red, and blue icons represent low, high, and uncertain risk of bias. Definitions of items are provided in S1 Table.