Background: Adolescent idiopathic scoliosis (AIS) is a tridimensional structural deformity of
the spine that may deteriorate progressively, leading to significant functional limitations and pain
problems. Several previous studies have implicated the rs4753426 single nucleotide polymorphism
in the melatonin receptor 1B (MTNR1B) gene in the etiology of AIS. However the sample sizes were
limited and the findings of those studies were inconsistent. An overall assessment of the evidence
supporting this association has not been previously conducted.
Objectives: To provide a comprehensive assessment and synthesis of the currently available
evidence on the association between rs4753426 and AIS.
Study Design: A systematic review and meta-analysis.
Setting: University hospital, China.
Methods: This review followed the Preferred Reporting Items for Systematic Review and MetaAnalyses guidelines. PubMed (MEDLINE), EMBASE, Scopus databases, and WANFANG databases
were systematically searched through December 2014 to identify relevant studies following a
sensitive strategy. Statistical analysis was performed using the Review Manager 5.2 software.
Summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated
using the fixed-effect inverse variance model for allelic (C vs. T) and genotypic comparisons.
Results: Four papers including 5 studies which involved 2,552 AIS cases and 2,738 controls
were identified for this meta-analysis. The results showed that C allele of the rs4753426 was
significantly associated with AIS (OR = 1.12, 95% CI: 1.03 – 1.21, P = 0.01). CT and CC genotypes
were 26% (OR = 1.26, 95% CI: 1.04 – 1.53, P = 0.01) and 28% (OR = 1.28, 95% CI: 1.05 – 1.56,
P = 0.01), respectively, more likely to have AIS compared with CC genotype. As for the dominant
model (CC+TT vs. TT), summary ORs showed statistically significant association with AIS (OR =
1.28, 95% CI: 1.06 – 1.53, P = 0.009). Compared with the CT+TT genotype, the summary ORs
of the CC genotype showed marginally statistically significant association with AIS (OR = 1.11, 95
% CI: 0.99 – 1.24, P = 0.07). The subgroup meta-analysis results showed the C allele and each
genotype were significantly associated with AIS in the Asian group but not in the Caucasian group.
Limitations: Paucity of available literature.
Conclusions: To our knowledge, there has been no meta-analysis to analyze the association
between rs4753426 polymorphism in the MTNR1B gene and AIS. This systematic review was
a comprehensive analysis of the currently available evidence, and found an overall significant
association of rs4753426 polymorphism with the risk of AIS, especially in the Asian population.
Further investigation of this association is necessary in other populations.
Key words: Adolescent idiopathic scoliosis, MTNR1B, Rs4753426, single nucleotide
polymorphism, occurrence, curve severity, meta-analysis