Role of LBX1 rs11190870 polymorphism in adolescent idiopathic scoliosis in the Acehnese population: A preliminary study

Abstract

Genome-wide association studies (GWAS) have identified the single nucleotide polymorphism (SNP) rs11190870 near the ladybird homeobox 1 (LBX1) gene as being associated with the susceptibility and severity of adolescent idiopathic scoliosis (AIS). However, no such genetic studies have been conducted in the Indonesian population. The aim of this study was to investigate the genetic profile of AIS patients in the Acehnese population, with a focus on LBX1 rs11190870, and to assess its association with disease severity. A total of 30 female AIS patients were included. Genetic analysis was performed to determine the rs11190870 genotype in each subject. The association between rs11190870 and curve progression, measured by Cobb angle, was analyzed using the Mann–Whitney U test. The T allele was found to be more prevalent (73.3%), with the TC genotype being the most common (53.3%). A significant association was observed between LBX1 rs11190870 and curve progression, where patients with the TT genotype exhibited a larger Cobb angle compared to those with TC or CC genotypes (p=0.01). This is the first study to characterize the genetic profile of AIS and its association with curve severity in the Acehnese population. These findings suggest that LBX1 rs11190870 may act as a disease modifier in AIS. Further studies with larger sample sizes are warranted to confirm the role of LBX1 rs11190870 in AIS susceptibility and severity in the Indonesian population.

Introduction

Adolescent idiopathic scoliosis (AIS), defined as a lateral spinal curvature of >10 degrees, is the most common spinal deformity found in children, affecting more females than males [1,2]. A recent systematic review and meta-analysis indicated that the prevalence of AIS was 1.68% in Asia, 1.22% in Europe, and 2.08% in South America [3]. Furthermore, this study also found that the pooled incidence of AIS was higher in females than males, 4.51% and 1.12%, respectively [3]. In Indonesia, a study in Surabaya identified a 2.93% AIS among 784 school-aged children with a female-to-male ratio of 4.7:1 [4].

Although extensive studies have been conducted on AIS, its etiology remains unclear. Several factors such as genetics, neuromuscular, hormones and metabolic dysfunction have been proposed as the plausible cause of AIS [1,5]. Previous studies have suggested that genetics play a significant role in the development of AIS through a complex interaction between genetic and environmental factors [6,7]. Genome-wide association studies (GWAS) have identified numerous loci as well as candidate genes associated with AIS, such as estrogen receptor 1 (ESR1), paired box 1 (PAX1), ladybird homeobox 1 (LBX1), G protein-coupled receptor 126 (GPR126), and solute carrier family 39 member 8 (SLC39A8) [8]. Among the genes, LBX1 – located on chromosome 10q24.31 – stands out as one of the most promising candidate genes in the etiology of AIS [1, 2]. A single nucleotide polymorphism (SNP) rs11190870 near LBX1 was associated with AIS susceptibility in the Japanese [9], Hong Kong [10], and Chinese populations [5]. Previous meta-analyses also supported these findings by suggesting that the rs11190870 polymorphism near LBX1 holds the potential as a predictive marker for AIS and among various genotypes, the T allele is highly associated with AIS susceptibility [1,2].

Although the role of rs11190870 near LBX1 in the occurrence of AIS seemed well established, its association with AIS severity remains debatable. Previous studies suggested the association between rs11190870 near LBX1 with curve progression in AIS, in which patients with TT and TC genotypes had a larger Cobb angle compared to those with CC genotypes [5,11,12]. However, a meta-analysis showed that SNP rs11190870 was not associated with the severity of the scoliosis curve in AIS [2]. Moreover, a replication study on a large number of patients in Japan found a marginal association between SNP rs11190870 and curve severity [13].

Despite the increasing body of evidence, most GWAS studies on AIS were conducted in East Asian populations [1,2,14]. To date, no study has characterized the genetic profile of AIS patients in the Southeast Asian population. Therefore, the aim of this study was to investigate the genetic profile of AIS patients in the Acehnese population in Indonesia, focusing on the LBX1 SNP rs11190870. Furthermore, this study also aimed to confirm the association between rs11190870 near LBX1 and the severity of AIS.

Methods

Study design and setting

A cross-sectional design was conducted on patients with AIS who visited the Orthopedic and Traumatology Department of Dr. Zainoel Abidin General Hospital, Banda Aceh, Indonesia. The study was conducted between July to December 2022. Clinical examination and blood sample collection were conducted at Dr. Zainoel Abidin General Hospital, while genetic examination was conducted at the Genetics Laboratory, Faculty of Veterinary Medicine, Universitas Syiah Kuala, Banda Aceh, and Prodia Laboratory, Jakarta, Indonesia.

The study protocol was reviewed and approved by the Institutional Health Research Ethics Committee and informed consent was obtained from the parents or legal guardians, along with assent from each participant before enrollment.

Study participants and variables

Female AIS patients of Acehnese ethnicity aged 10–18 years with Cobb angle >10 degrees who visited the Spine Division, Orthopedic and Traumatology Department, Dr. Zainoel Abidin General Hospital, Banda Aceh, Indonesia between 2021 and 2022 were invited to participate in this study. All of them underwent clinical examination by a spine surgeon, radiological examination, and genetic examination. Individuals with secondary scoliosis and neurological deficits were excluded from this study.

Demographic characteristics (age, ethnicity, residence) were recorded and preliminary clinical assessments (plumb line, scoliometer measurements, and Adam’s test) were conducted. Radiological examinations were conducted at the Radiology Department and included posteroanterior (PA) and lateral standing spinal radiographs. These were used to measure Cobb angles to quantify curve severity, assess vertebral rotation using the Nash-Moe classification, identify the scoliosis apex, evaluate coronal balance using the Central Sacral Vertical Line (CSVL), determine skeletal maturity based on the Risser sign, and characterize the sagittal spinal profile (hypokyphotic, normokyphotic, or hyperkyphotic) based on thoracic Cobb angles. Genetic examination was conducted on all subjects to examine the rs11190870 near LBX1 and its genotypes.

SNP genotyping

Genomic DNA was extracted from venous blood using Qiagen DNeasy Blood and Tissue Kit (Qiagen GmbH, Hilden, Germany). Genetic analyses focusing on the LBX1 SNP rs11190870 were conducted at the Genetics Laboratory, Faculty of Veterinary Medicine, Universitas Syiah Kuala, and Prodia Laboratory, Jakarta, employing TaqMan SNP Genotyping Assays and Real-Time PCR (Bio-Rad, Hercules, California, USA) to determine allelic variants (TT, TC, CC).

Statistical analysis

Descriptive statistics (mean±SD, median with interquartile range, frequency, and percentage) were used to summarize demographic, clinical, and radiological variables. The potential role of rs11190870 in disease progression was assessed quantitatively with the Cobb angle. Cobb angle– measured through spinal X-ray–was classified into three categories: mild (10°–25°), moderate (25°–45°), and severe (>45°) [15]. The median score of the Cobb angle was used to analyze the association of LBX1 SNP rs11190870 genotype and curve progression using an independent Student t-test or the Mann-Whitney U test, depending on the normality of the data. Statistical significance was set at p<0.05, and all statistical analyses were carried out using SPSS version 27 (IBM Corp., Armonk, NY, USA).

Results

In total, 30 female AIS patients of Aceh ethnicity participated in this study. The mean age was 15.8 years, with a mean Cobb angle of 26.49 degrees (Table 1). Most of the participants had right hump (70%), were categorized in C CSVL (63.3%), had Risser sign≥4 (63.3%), and had normokyphotic thoracic sagittal profile (53.3%). Demographic and clinical characteristics of study participants are presented in (Table 1).

Table 1.

Demographic and clinical characteristics of study participants

Characteristics	Frequency (percentage)
Age (year), mean±SD	15.8±1.84
Scoliometry, mean±SD	37.01±20.46
Plumb line test
Right	21 (70.0)
Left	9 (30.0)
Cobb angle (degree), mean±SD	26.49±13.8
Mild (10°–25°); n (%)	5 (16.7)
Moderate (25°–45°)	22 (73.3)
Severe (>45°)	3 (10.0)
Central sacral vertical line (CSVL)
A	6 (20.0)
B	10 (33.3)
C	14 (46.7)
Nash Moe, median (min-max)	1 (0–3)
Risser Sign, median (min-max)	4 (1–5)
Risser<4	11 (36.7)
Risser≥4	19 (63.3)
Thoracic sagittal profile
Hypokyphotic	14 (46.7)
Normokyphotic	16 (53.3)

LBX1 SNP rs11190870 genotype study

Analysis of LBX1 SNP rs11190870 revealed that the T allele was more prevalent (73.3%) than the C allele (26.7%) among AIS patients in the Acehnese population. A total of 16 individuals (53.3%) presented with a heterozygote TC genotype, while the other 14 (46.7%) presented with a homozygote TT genotype. No patients presented with the homozygote CC genotype in this study (Table 2).

Table 2.

Characteristics of study participants based on their genotypes

Characteristics	LBX1 rs11190870 genotype		p-value
	Homozygote TT (n=14)	Heterozygote TC (n=16)
Age (year), mean±SD	15.18dl.35	15.68±2.15	0.801
Scoliometry, median (min-max)	8 (4.5–22)	5 (5–18)	0.190
Plumb line test			0.122
Right	7 (50.0)	17 (81.3)
Left	7 (50.0)	3 (18.7)
Cobb angle (degree)			0.006*
Mild (10°–25°)	0 (0.0)	5 (31.3)
Moderate (25°–45°)	11 (78.6)	11 (68.8)
Severe (>45°)	3 (21.4)	0 (0.0)
Central sacral vertical line (CSVL)			0.291
A	3 (21.4)	3 (18.8)
B	2 (14.3)	8 (50)
C	9 (64.3)	5 (31.3)
Nash Moe			0.124
Neutral	3 (21.4)	6 (37.5)
Grade 1	3 (21.4)	4 (25)
Grade 2	5 (35.7)	6 (37.5)
Grade 3	3 (21.4)	0 (0.0)
Risser sign			0.236
Risser <4	6 (42.9)	3 (18.8)
Risser ≥4	8 (57.1)	13 (81.3)
Thoracic sagittal profile			0.090
Hypokyphotic	11 (78.6)	16 (100.0)
Normokyphotic	3 (21.4)	0 (0.0)

^*Statistically significant at p<0.05

Characteristics of study participants based on their genotypes are presented in (Table 2). Both TT and TC genotype groups shared similar traits in age (mean age was 15 in both groups), severity (most of the patients in both groups had moderate severity as measured with Cobb angle), and maturity of the curvature (most of the patients in both groups had Risser ≥4) (Table 2). The vast majority of patients in the TC group (81.3%) had a hump on the right side while those in the group had an equal number of the right and left humps. Most of the patients in the TC group (75%) had thoracal apex, in contrast to the TT groups where most patients (57.1%) had lumbar apex. Patients with the TT genotype showed a bigger median score (8) than those with the TC genotype. No significant association was found between LBX1 genotype and coronal balance (measured by central sacral vertical line (CVSL)), vertebral rotation (assessed using Nash Moe classification), skeletal maturity (measured with Risser sign), and sagittal profile (Table 2). However, a significant association was found between LBX1 genotype and curve severity measured by Cobb angle (p=0.006). The characteristics of patients in both groups and their association with the LBX1 genotype are presented in (Table 2).

Association of LBX1 rs11190870 and curve progression

Further analysis was conducted to confirm the association between LBX1 genotype and curve progression. This study found a significant difference between the median Cobb angle in patients with the TT and TC genotypes, 26 degrees and 22 degrees, respectively, p=0.01 (Figure 1).

Figure 1.

Comparison of median Cobb angle between the TT and TC genotypes.

Discussion

This study found that the majority of AIS patients in the Acehnese population had T alleles. Meta-analyses have consistently implicated the T allele at rs11190870 as a risk factor for AIS [1, 2], with individuals carrying the TT genotype having higher odds of developing AIS due to the presence of two risky T alleles [16,17]. Furthermore, a study in the Southeast European population also found that individuals with the TT genotype had a 35% higher risk of developing AIS than those with other genotypes [18]. However, some studies, such as Li et al. [19], did not find a significant effect on the TT genotype, indicating variability in genetic susceptibility across different ethnic groups. Given Aceh’s complex ancestral background, including influences from Arab, Chinese, Indian, and European lineages [20], it is plausible that the LBX1 variant distributions might mirror other diverse populations, resulting in different haplotypes and linkage disequilibrium (LD) patterns that affect AIS susceptibility.

Regarding patients’ age, this study found that the mean age of AIS patients in the Acehnese population is 15 years old, regardless of the rs11190870 genotype. This finding aligns with studies from Scotland and Norway, which reported the most common onset of AIS in females at around 14 to 14.5±2.1 years of age [21]. Similarly, research conducted in Padang between 2013 and 2019 also identified female AIS patients with a mean age of 15.13 years, consistent with the global trend that AIS more commonly affects females [22]. Epidemiological evidence suggests that females have up to five-fold greater risk of curve progression than males, potentially due to hormonal influences, earlier growth spurts, postural factors, estrogen-receptor involvement, and differences in physical activity levels [23,24].

This study found no significant association between LBX1 rs11190870 genotype and clinical characteristics such as age, coronal balance (measured by CVSL), vertebral rotation (assessed using Nash Moe classification), skeletal maturity (measured with Risser sign), and sagittal profile. Only curve severity was significantly associated with the LBX1 rs11190870 genotype. However, it is important to highlight these clinical characteristics, particularly the skeletal maturity and curve severity. Most of the patients in this study (in both genotype groups) had moderate severity (Cobb angle 25°–45°) and Risser ≥4. These two parameters are important in deciding the management of AIS. According to the International Scientific Society on Scoliosis Orthopedic and Rehabilitation Treatment (SOSORT) guideline 2016, the treatment for AIS patients with moderate severity (Cobb angle 25°–45°) and Risser ≥4 includes physiotherapeutic scoliosis-specific exercises (PSSE) and full-time use of a rigid brace. Surgery is only indicated in AIS patients with Risser ≥4 and Cobb angle >45°[25]. Once the skeletal maturity is reached (Risser

≥4), progressivity of the curvature is likely to happen. Thus, conservative treatment with exercise and bracing should be adequate. However, low compliance with bracing and exercise might lead to severe AIS, which requires surgical intervention.

This study found a significant association between LBX1 rs11190870 genotype and curve severity (p=0.01), in which AIS patients with the TT genotype had a larger Cobb angle than those with the TC or CC genotype. This is in line with a previous study in the Chinese population that suggested the effect of the T allele on curve progression [5]. This finding also confirms previous studies suggesting that the T allele is the risk allele that might be involved in both the initiation and progression of AIS [5,9,10]. The ability to distinguish individuals at high risk of curve progression is pivotal as it would facilitate early treatment, which is both effective for patients and economically beneficial for their families.

Several studies have been conducted to examine the association between the rs11190870 genotype and the severity of AIS (Table 3). This association was first investigated by Jiang et al.

Table 3.

Comparison of studies assessing the association between LBX1 rs11190870 and AIS severity

Study	Population	Number of AIS patients	Cobb angle of TT (mean±SD)	Cobb angle of TC (mean±SD)	p-value
Jiang et al., 2013 [5]	Chinese	314	34.1±11.6	32.0±13.8	0.0005*
Gao et al., 2013 [11]	Chinese	234	30.10±14.81	30.73±19.56	0.33
Takahashi et al., 2015 [12]	Japanese	2,068	39.0±15.4	40.2±16.4	0.20
Takahashi et al., 2018 [13]	Japanese	1,860	41.7±16.5	42.0±16.6	0.13
Man et al., 2019 [14]	Chinese	176	47.2±15.3	47.4±19.4	0.679

^*Statistically significant at p<0.05

[5] in a Han Chinese population. This study found that AIS patients with the TT genotype had a significantly larger Cobb angle compared to individuals with the TC or CC genotype (p=0.005). Following this study, four studies (two on the Chinese population and two on the Japanese population) were conducted to further investigate this association. However, none of these studies found a significant association between rs11190870 and curve severity in AIS patients [11-14]. In the present study, we found that AIS patients with the TT genotype had significantly higher Cobb angles compared to those with the TC genotype. This finding raises further questions regarding the potential of LBX1 rs11190870 in predicting AIS severity.

Origi

Several theories have been proposed on how LBX1 rs11190870 influences the severity of AIS. The SNP rs11190870 has been consistently associated with AIS susceptibility and severity across multiple populations. Studies in East Asian populations, including Chinese and Japanese cohorts, have shown that the T allele of rs11190870 is significantly associated with an increased risk of AIS and larger Cobb angles, indicating greater curve severity [5,13,14,26] . In a Han Chinese population, AIS patients with the TT genotype at rs11190870 had significantly larger Cobb angles compared to those with the TC or CC genotypes [5]. Similarly, a replication study in Japanese patients confirmed that rs11190870 was associated with curve severity, with the T allele correlating with more severe spinal curvature [13]. These findings suggest that rs11190870 influences the progression and severity of AIS.

The LBX1 gene has been implicated in the pathogenesis of AIS through its role in regulating paraspinal muscle development and energy metabolism. A study showed that LBX1 expression is asymmetric in the paraspinal muscles of AIS patients, with a higher expression on the convex side of the curvature compared to the concave side [27]. This asymmetry may contribute to the progression of spinal curvature by altering the balance of muscle growth and function around the spine. Furthermore, functional assays have demonstrated that silencing LBX1 in myosatellite cells inhibits cell viability and myotube formation, highlighting the importance of LBX1 in muscle development [28]. LBX1 has also been linked to energy metabolism, where a loss of LBX1 in skeletal muscle results in increased systemic energy expenditure and resistance to high-fat diet-induced obesity [29]. This suggests that LBX1 may play a role in regulating metabolic pathways that influence the energy balance of paraspinal muscles, potentially contributing to the progression of scoliosis.

Animal models have provided valuable insights into the role of LBX1 in AIS pathogenesis. In zebrafish, overexpression of LBX1 or its homologs (lbx1a, lbx1b, and lbx2) caused body axis deformation through defects in convergent extension during embryonic development, contributing to the severity of AIS [30]. These defects were associated with downregulation of wnt5b, a ligand in the non-canonical Wnt/planar cell polarity (PCP) pathway, which is critical for proper tissue orientation and morphogenesis. Rescue experiments with wnt5b or RhoA, a downstream effector of Wnt/PCP signaling, attenuated the curvature phenotype, suggesting that LBX1 overexpression disrupts Wnt/PCP signaling, leading to axial defects [30]. In mice, deletion of a conserved genomic region near LBX1 resulted in vertebral rotation and proprioceptive deficits, phenotypes reminiscent of human AIS [31]. These findings underscore the importance of LBX1 in maintaining proper spinal alignment and function.

Epigenetic modifications, such as DNA methylation, have been implicated in the regulation of LBX1 expression in AIS. A study examining methylation levels of the LBX1 promoter in deep paravertebral muscles found that patients with severe AIS (Cobb angle >70°) had higher methylation levels at specific CpG sites on the convex side of the curvature compared to those with less severe curves [32]. This suggests that epigenetic modifications may play a role in the localized regulation of LBX1 expression, contributing to the progression and severity of scoliosis. Haplotype analysis has revealed that rs11190870 and other SNPs near LBX1 form distinct haplotypes with opposite effects on AIS risk. A recessive risk haplotype (TTA) was associated with increased susceptibility, while a co-dominant protective haplotype (CCG) reduced the risk of AIS [33]. These findings highlight the complexity of genetic regulation at the LBX1 locus and the ntial for population-specific effects. Interestingly, the association of rs11190870 with AIS has not been universally replicated in all populations. A study in a South-Asian Indian population found no significant association between rs11190870 and AIS susceptibility, suggesting genetic heterogeneity in the etiology of AIS across different populations [34].

Based on the evidence from genetic, functional, and epigenetic studies, a proposed mechanism for the role of rs11190870 in AIS severity is as follows: (a) genetic predisposition, the rs11190870 SNP increases LBX1 expression by enhancing the transcriptional activity of its promoter region [28,30]; (b) disruption of Wnt/PCP signaling, overexpression of LBX1 disrupts Wnt/PCP signaling, leading to defects in convergent extension and axial elongation during embryonic development [30]; (c) asymmetric muscle development, elevated LBX1 expression in paraspinal muscles on the convex side of the curvature contributes to asymmetric muscle growth and function, exacerbating spinal curvature [27]; and (d) epigenetic regulation: DNA methylation at the LBX1 promoter region may locally regulate LBX1 expression in paraspinal muscles, further contributing to the progression and severity of scoliosis [32]. The proposed mechanism for the role of rs11190870 in AIS severity is illustrated in (Figure 2). Key findings on the influence of LBX1 rs11190870 and AIS are summarized in (Table 4).

Figure 2.

Presence of rs11190870 SNP (especially the T allele) alters the regulation of LBX1 expression, resulting in impaired migration and differentiation of muscle precursor cells. Consequently, the development of paraspinal myocytes is disrupted, leading to an imbalance in paraspinal muscle function (between the convex and concave sides), which in turn causes postural abnormalities, specifically scoliosis.

Table 4.

Summary of key findings on rs11190870 and LBX1 in AIS

Study focus	Key findings	Studies
Genetic association	rs11190870 is associated with AIS susceptibility and severity in East Asian populations.	[5,13,14,26]
Functional role of LBX1	LBX1 regulates paraspinal muscle development and energy metabolism.	[27-29]
Animal models	Overexpression of LBX1 causes body axis deformation and disrupts Wnt/PCP signaling.	[30]
Epigenetic regulation	Methylation of LBX1 promoter correlates with AIS severity	[32]
Population-specific effects	No association of 1^11190870 with AIS in South-Asian Indian populations	[34]

This is the first study examining the genetic profile of the Indonesian population. However, its relatively small sample size should be considered when interpreting the results. Despite the growing prevalence of AIS in the Asian population, Indonesia lacks a screening program for AIS, resulting in a small number of patients visiting the study center. Another limitation is the case-only design, which limits further analysis of the association between LBX1 rs11190870 and AIS in the Acehnese population. Nevertheless, as the first study conducted in Indonesia and Southeast Asia, this study serves as a crucial foundation for future research with a better design, larger sample size, and more diverse ethnic representation to further investigate the role of LBX1 rs11190870 in AIS.

Conclusion

This is the first study to examine the characteristics of genetic profiles and their association with curve progression in the Acehnese population. The findings of this study suggest that the rs11190870 polymorphism might serve as a predictor of AIS severity in the Acehnese population. This study also highlights the importance of scoliosis screening programs for school-aged children in Aceh since early detection can help prevent the progressivity of the curve and lead to more conservative treatment instead of surgical interventions. Further investigation through integrated genome-wide and epigenome-wide association studies to examine the role of LBX1 rs11190870 in the susceptibility and severity of AIS in the Indonesian population is warranted.

Ethics approval

The study protocol was reviewed and approved by the Health Research Ethics Committee, Faculty of Medicine, Universitas Syiah Kuala–RSUDZA Banda Aceh (Approval No. 410/EA/FK-RSUDZA/2021), and informed consent was obtained from the parents or legal guardians, along with assent from each adolescent participant before enrollment.

Competing interests

All the authors declare that there are no conflicts of interest.

Funding

This study received no external funding.

Underlying data

Derived data supporting the findings of this study are available from the corresponding author on request.

Declaration of artificial intelligence use

We hereby confirm that no artificial intelligence (AI) tools or methodologies were utilized at any stage of this study, including during data collection, analysis, visualization, or manuscript preparation. All work presented in this study was conducted manually by the authors without the assistance of AI-based tools or systems.

How to cite

Aulia TN, Gatam L, Yaman A, Djufri D. Role of LBX1 rs11190870 polymorphism in adolescent idiopathic scoliosis in the Acehnese population: A preliminary study. Narra J 2025; 5 (2): e2038 - http://doi.org/10.52225/narra.v5i2.2038.