Polymorphisms in Vitamin D Receptor Genes in Association with Childhood Autism Spectrum Disorder

Zhang, Zengyu; Li, Sufang; Yu, Lianfang; Liu, Jun

doi:https://doi.org/10.1155/2018/7862892

Disease Markers

On this page

Abstract Introduction Materials and Methods Results Discussion Conclusion Abbreviations Additional Points Ethical Approval Conflicts of Interest Authors’ Contributions Acknowledgments References Copyright Related Articles

Research Article | Open Access

Volume 2018 | Article ID 7862892 | https://doi.org/10.1155/2018/7862892

Polymorphisms in Vitamin D Receptor Genes in Association with Childhood Autism Spectrum Disorder

Zengyu Zhang,¹Sufang Li,¹Lianfang Yu,¹and Jun Liu²

Academic Editor: Hubertus Himmerich

Received02 Jun 2017

Revised18 Aug 2017

Accepted19 Sept 2017

Published11 Jan 2018

Abstract

Both genetic and environmental factors have been implicated in the etiology of autism spectrum disorder (ASD). This case-control study aimed to determine the association of single-nucleotide polymorphisms (SNPs) rs731276 (TaqI), rs1568820 (Cdx2), rs1544410 (BsmI), and rs2228570 (FokI) in the vitamin D receptor (VDR) gene with susceptibility of childhood ASD and severity of the disease. A total of 201 children with ASD and 200 healthy controls from the Han Chinese population were recruited. SNP genotyping was carried out by TaqMan probe-based real-time PCR using genomic DNA extracted from blood cells. Among four examined SNPs, only the CT genotype (odds ratio (OR) = 1.96, 95% confidence interval (CI) = 1.05–3.68, ) and the C allele (OR = 1.88, 95% CI = 1.02–3.46, ) of the rs731276 were significantly associated with increased risks of childhood ASD. None of the SNPs were associated with severity of childhood ASD. Our results reveal that certain polymorphisms in the VDR gene are a risk factor related to childhood ASD in the Han Chinese population.

1. Introduction

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by difficulty in social interactions, challenges in language and speech, and a tendency of repetitive behaviors [1]. Though the etiology accounting for ASD remains unknown, both genetic and environmental factors have been implicated as major risk factors of the disease [2–4]. Identification of these factors may assist with unraveling the etiology and develop novel prevention and treatment for the disease.

As a steroid hormone, vitamin D is known to be essential for calcium hemostasis and bone health. It also plays important roles in neural differentiation, immune modulation, antioxidation, and neurotrophic and neuroprotective actions, all of which are critical for embryogenesis and neurodevelopment [5–8]. The malfunctions of the vitamin D pathway may thus be attributable to the development of ASD. Previous studies have reported an association between vitamin D and ASD. Low serum vitamin 25(OH)D levels were associated with an increased risk of ASD [9, 10]. Vitamin D deficiency during pregnancy or early childhood was considered to be a risk factor for ASD [11, 12]. Supplementation of vitamin D for mothers of children with ASD during pregnancy and for their newborn siblings reduced the recurrence rate [13]. The varied prevalence of ASD in children born in different seasons, latitudes, and with varied skin pigmentation implied the role of vitamin D in the development of the disease [14]. The offspring exposed to vitamin D deficiency during gestation displayed autism-relevant structural and functional abnormalities in the brain and behavior, the same as those in animal studies [15, 16].

Vitamin D transmits signaling through binding to its receptor (VDR). The VDR gene is located on chromosome 12q13 consisting of nine exons and eight introns [17]. Several SNPs have been identified in this gene. The rs731236 (Taq1) is positioned at exon 9. This polymorphism changes protein structure and alters the binding specificity of vitamin D [18]. The VDR rs11568820 (Cdx2) is located in the promoter region. This polymorphism may influence the transcriptional activity [19]. The rs1544410 (BsmI) at intron 8 affects gene expression through regulation of mRNA stability [20]. The rs2228570 (FokI) is positioned at the start codon of exon 2. This polymorphism alters the initiation sites [18] and consequently generates two different-sized proteins [21]. Polymorphisms of VDR may also be involved in the development of ASD by influencing the functions of vitamin D pathway.

The role of VDR polymorphisms in the development of ASD has not been well studied. The results are still inconclusive [22, 23]. In this case-control study, the correlation between SNPs rs731276, rs1568820, rs1544410, and rs2228570 in the VDR gene and childhood ASD and its severity was examined in a Han Chinese population.

2. Materials and Methods

From September 2012 to June 2016, 201 Han Chinese children affected with ASD were recruited from hospitals in the Xiaoshan District of Zhejiang Province. Age- and gender-matched healthy Han Chinese children () were recruited from both a preschool and a primary school in the same district [24]. This study was approved by the Medical Ethics Committee of Zhejiang Xiaoshan Hospital. Informed consent was obtained from parents or guardians of all children.

DNA was extracted from blood cells using the Qiagen Blood DNA Mini kit (QIAGEN China (Shanghai) Co. Ltd, Shanghai, China) following the protocol described previously [24, 25].

The data was analyzed using SAS 9.3 software (SAS Institute Inc., Cary, NC), and values < 0.05 were considered statistically significant. The χ² analysis was applied for the Hardy-Weinberg equilibrium test. Logistic regression analysis was applied to determine the relationship between SNPs and the risk of childhood ASD or severity of the disease. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Linkage disequilibriums (LD) among rs731276, rs1568820, rs1544410, and rs2228570 were analyzed using the SHEsis computer program [26].

3. Results

Genotype distributions of SNP rs731276, rs1568820, rs1544410, and rs2228570 were all in accordance with Hardy-Weinberg genetic equilibrium in both the control and case groups (Table 1).

Instead of three genotypes for each SNP, our results showed only two genotypes within this population, TT and CT of rs731276 and GG and AG of rs1544410. Logistic regression analysis showed that the CT genotype of rs731276 (OR = 1.96, 95% CI = 1.05–3.68, ) and the C allele of the rs731276 were significantly associated with an increased risk of childhood ASD (OR = 1.88, 95% CI = 1.02–3.46, ). There were no significant differences in the genotype distributions and allele frequencies between the case and control groups for the other three SNPs (Table 2).

The relationship between these SNPs and childhood ASD was further analyzed using dominant and recessive models for SNPs rs1568820 and rs2228570. No significant difference in genotypes of either SNP between children with ASD and healthy controls was observed in any of the models (Table 3).

These children affected with ASD were classified into mild-to-moderate and severe groups based on the scores of the Childhood Autism Rating Scale (CARS). There were 122 children with mild-to-moderate ASD and 79 with severe ASD. Logistic regression analysis showed that there was no significant association of these studied SNPs in the VDR gene regarding the severity of childhood ASD (Table 4).

Pair-wise tests showed a strong linkage disequilibrium in between VDR rs731276 and rs1544410 (, ), but not among other SNPs (Figure 1). There was no significant correlation between haplotypes (T-G and C-A) of rs731276-rs1544410 and risk of childhood ASD (Table 5).

4. Discussion

In this case-control study, we determined the relationship between SNPs in VDR genes and childhood ASD and its severity in a Han Chinese population. Our results showed that the CT genotype and C allele of VDR rs731276 were significantly associated with an increased risk of childhood ASD. There was no significant difference in genotype and allele frequencies of SNPs rs1568820, rs1544410, and rs2228570 between children with ASD and healthy controls. None of the studied SNPs were associated with severity of childhood ASD.

Two previous studies have thus far reported an association between certain SNPs in the VDR gene and ASD. Schmidt et al. examined SNPs in VDR genes of maternal, paternal, and child samples from children participating in the population-based CHARGE (CHildhood Autism Risks from Genetics and the Environment) case-control study. Their results showed that the paternal CC genotype of rs731236 and the AA genotype of rs1544410, individually or in combination, were significantly associated with an increased risk for ASD. However, no significant association between the above two SNPs and ASD was observed in autistic children or their mothers [22]. In a separate study, the SNPs in the VDR gene was examined among 237 children with ASD and 243 healthy controls from the Turkish population. Their data showed that the CC genotype of rs731236, the TT genotype of rs2228570, and the AA genotype of rs1544410 were significantly associated with increased risk of childhood ASD. The genotype of rs7975232 was not a significant risk factor for childhood ASD. The frequency of haplotype GTTT of rs1544410-rs731236-rs2228570-rs7975232 was significantly higher in children with ASD than in controls. The frequencies of the ATCG and GTCT haplotypes were statistically lower in children with ASD compared to healthy controls [23]. These two studies suggest that polymorphisms in the VDR gene may be associated with the risk of ASD, whereas different populations may also have their specific ASD-related SNPs.

Our results showed that both the CT genotype and the C allele of rs731236 in VDR were associated with increased risk of childhood ASD in this Han Chinese population. There were no significant differences in genotypes and allele frequencies of the SNPs rs1568820, rs1544410, and rs2228570 between children with ASD and healthy controls. No association between all four SNPs and the severity of childhood ASD was observed in this study. In addition, the rs731236 and rs1544410 showed a high linkage disequilibrium. However, both haplotypes T-C and C-T of rs731236-rs1544410 were not significantly associated with childhood ASD. Interestingly, our study showed that only two genotypes of Taq1 and Rs1544410 were observed in this Han Chinese population. This finding is consistent with the results of a previous study in a Chinese population [27]. Our results provide strong evidence that certain polymorphisms in the VDR gene are associated with risk of childhood ASD. It is essential to identify population-specific SNPs related to childhood ASD.

The polymorphisms in VDR genes have been correlated with serum 25(OH)D levels. Surprisingly, the genotypes or alleles related to a higher risk of ASD are associated with increased concentration of 25(OH)D. Coskun et al. discovered that the TT genotype of rs2228570 was significantly associated with increased risk of childhood ASD and with higher serum 25(OH)D in children with ASD [23]. Inconsistent with this finding, carriers of the TT genotype had significantly higher serum 25(OH)D concentrations in multiple sclerosis patients [28, 29]. Increased serum 25(OH)D levels in patients with the variant TT genotype may be a compensatory response due to reduced VDR activity [23]. In addition, both the Coskun group and our group identified that the C allele of rs731236 of the VDR gene was associated with increased risk of childhood ASD. In healthy subjects, from a Turkish cohort, the C allele carriers for rs731236 of the VDR gene had significantly higher levels of serum 25(OH)D [30]. In contrast, low levels of serum 25(OH)D were associated with an increased risk of ASD [9, 10]. It will be of clinical significance to study the role of the interaction between VDR polymorphisms and vitamin D status in the development of ASD.

Polymorphisms in the VDR gene have been associated with risks for many other neuropsychiatric disorders. SNPs rs731236 and rs1544410 in the VDR gene were associated with risk of multiple sclerosis in Mexican [31] and Kuwaiti studies [32]. A meta-analysis revealed that rs1544410 and rs2228570 were associated with susceptibility to Parkinson’s disease and rs731236 was related to with Alzheimer’s disease [33]. SNP rs2228570 was found to be significantly associated with cognitive decline in Parkinson’s disease [34]. Jiang et al., reported that SNPs rs2228570 and rs7975232 were risk factors for childhood temporal lobe epilepsy [35]. No association of rs2228570 in the VDR gene with multiple sclerosis was found in other studies [29, 36]. SNPs rs7975232, rs731236, and rs1544410 in the VDR gene are not a predictor for disease disability progression rate in multiple sclerosis in Slovaks [37]. No correlation between Parkinson’s disease and the VDR polymorphisms, including rs1544410, rs2228570, rs7975232, and rs731236, was found in a Korean population [38].

Limitations of this case-control study include a relatively small sample size. Only 4 SNPs of the VDR gene were determined, but no blood markers of vitamin D or calcium were examined in this study. A much higher proportion of boys with ASD was recruited in our study, with a ratio nearly 11 : 1 of boys to girls. Furthermore, all children with ASD enrolled in this study were patients being treated in the hospitals of the Xiaoshan District in Zhejiang Province. These patients may not be representative of all children with ASD from the general population of Chinese Han.

5. Conclusion

Our results suggest that certain polymorphisms in the VDR gene may cause susceptibility to the development of childhood ASD. More validation studies, with large sample sizes, are needed to validate the findings revealed in this study.

Abbreviations

ASD:	Autism spectrum disorder
CARS:	Childhood Autism Rating Scale
LD:	Linkage disequilibriums
SNP:	Single-nucleotide polymorphism
VDR:	Vitamin D receptor.

Additional Points

Summary Statement. Certain polymorphisms in the vitamin D receptor gene are a risk factor for the childhood autism spectrum disorder. This finding facilitates our understanding of the genetic mechanisms of the disease.

Ethical Approval

This study was approved by the Medical Ethics Committee of Zhejiang Xiaoshan Hospital.

Conflicts of Interest

The authors have declared no conflicts of interests with respect to the research, authorship, and/or publication of this article.

Authors’ Contributions

Lianfang Yu and Jun Liu designed and initiated the study. Zengyu Zhang and Lianfang Yu recruited and diagnosed patients and controls. Zengyu Zhang, Lianfang Yu, and Jun Liu collected samples and performed genotyping. Zengyu Zhang, Lianfang Yu, and Jun Liu analyzed the data and drafted the manuscript. All authors reviewed and approved the final manuscript.

Acknowledgments

The authors are grateful to Drs. Shihua Wang and Kristin Best for reviewing the manuscript. This work was supported by grants from the Health and Family Planning Commission of Zhejiang Province (2014KYB225); the Science and Technology Commission of Hangzhou City (20140633B48); the Science Technology Department of Zhejiang Province (2017C33205); the Hangzhou Municipal of Science and Technology Commission (20163501Y82); and the Health and Family Planning Commission of Hangzhou (2016B26).

References

American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, 5th edition, 2013, Arlington VAPP.
N. T. Vijayakumar and M. V. Judy, “Autism spectrum disorders: integration of the genome, transcriptome and the environment,” Journal of the Neurological Sciences, vol. 364, pp. 167–176, 2016.
View at: Publisher Site | Google Scholar
J. R. Homberg, E. J. Kyzar, M. L. Scattoni et al., “Genetic and environmental modulation of neurodevelopmental disorders: translational insights from labs to beds,” Brain Research Bulletin, vol. 125, pp. 79–91, 2016.
View at: Publisher Site | Google Scholar
A. Modabbernia, E. Velthorst, and A. Reichenberg, “Environmental risk factors for autism: an evidence-based review of systematic reviews and meta-analyses,” Molecular Autism, vol. 8, p. 13, 2017.
View at: Publisher Site | Google Scholar
N. Maruotti and F. P. Cantatore, “Vitamin D and the immune system,” The Journal of Rheumatology, vol. 37, pp. 491–495, 2010.
View at: Publisher Site | Google Scholar
L. R. Harms, T. H. Burne, D. W. Eyles, and J. J. McGrath, “Vitamin D and the brain,” Best Practice & Research, vol. 25, pp. 657–669, 2011.
View at: Publisher Site | Google Scholar
E. Kocovska, F. Gaughran, A. Krivoy, and U. C. Meier, “Vitamin-D deficiency as a potential environmental risk factor in multiple sclerosis, schizophrenia, and autism,” Frontiers in Psychiatry, vol. 8, p. 47, 2017.
View at: Google Scholar
J. J. Cannell, “Vitamin D and autism, what’s new?” Reviews in Endocrine & Metabolic Disorders, vol. 18, no. 2, pp. 183–193, 2017.
View at: Publisher Site | Google Scholar
E. Kocovska, G. Andorsdottir, P. Weihe et al., “Vitamin d in the general population of young adults with autism in the faroe islands,” Journal of Autism and Developmental Disorders, vol. 44, no. 12, pp. 2996–3005, 2014.
View at: Publisher Site | Google Scholar
A. Bener, A. O. Khattab, and M. M. Al-Dabbagh, “Is high prevalence of vitamin D deficiency evidence for autism disorder?: in a highly endogamous population,” Journal of Pediatric Neurosciences, vol. 9, no. 3, pp. 227–233, 2014.
View at: Publisher Site | Google Scholar
E. Fernell, S. Bejerot, J. Westerlund et al., “Autism spectrum disorder and low vitamin D at birth: a sibling control study,” Molecular Autism, vol. 6, p. 3, 2015.
View at: Publisher Site | Google Scholar
J. Chen, K. Xin, J. Wei, K. Zhang, and H. Xiao, “Lower maternal serum 25(OH) D in first trimester associated with higher autism risk in Chinese offspring,” Journal of Psychosomatic Research, vol. 89, pp. 98–101, 2016.
View at: Publisher Site | Google Scholar
G. Stubbs, K. Henley, and J. Green, “Autism: will vitamin D supplementation during pregnancy and early childhood reduce the recurrence rate of autism in newborn siblings?” Medical Hypotheses, vol. 88, pp. 74–78, 2016.
View at: Publisher Site | Google Scholar
D. W. Eyles, T. H. Burne, and J. J. McGrath, “Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease,” Frontiers in Neuroendocrinology, vol. 34, no. 1, pp. 47–64, 2013.
View at: Publisher Site | Google Scholar
C. W. Levenson and S. M. Figueiroa, “Gestational vitamin D deficiency: long-term effects on the brain,” Nutrition Reviews, vol. 66, no. 12, pp. 726–729, 2008.
View at: Publisher Site | Google Scholar
D. W. Eyles, F. Feron, X. Cui et al., “Developmental vitamin D deficiency causes abnormal brain development,” Psychoneuroendocrinology, vol. 1, 34 Supplement, pp. S247–S257, 2009.
View at: Publisher Site | Google Scholar
J. M. Zmuda, J. A. Cauley, and R. E. Ferrell, “Molecular epidemiology of vitamin D receptor gene variants,” Epidemiologic Reviews, vol. 22, no. 2, pp. 203–217, 2000.
View at: Google Scholar
A. G. Uitterlinden, Y. Fang, J. B. Van Meurs, H. A. Pols, and J. P. Van Leeuwen, “Genetics and biology of vitamin D receptor polymorphisms,” Gene, vol. 338, no. 2, pp. 143–156, 2004.
View at: Publisher Site | Google Scholar
H. Yamamoto, K. Miyamoto, B. Li et al., “The caudal-related homeodomain protein Cdx-2 regulates vitamin D receptor gene expression in the small intestine,” Journal of Bone and Mineral Research, vol. 14, pp. 240–247, 1999.
View at: Publisher Site | Google Scholar
C. J. Decker and R. Parker, “Diversity of cytoplasmic functions for the 3′ untranslated region of eukaryotic transcripts,” Current Opinion in Cell Biology, vol. 7, no. 3, pp. 386–392, 1995.
View at: Google Scholar
T. Saijo, M. Ito, E. Takeda et al., “A unique mutation in the vitamin D receptor gene in three Japanese patients with vitamin D-dependent rickets type II: utility of single-strand conformation polymorphism analysis for heterozygous carrier detection,” The American Journal of Human Genetics, vol. 49, no. 3, pp. 668–673, 1991.
View at: Google Scholar
R. J. Schmidt, R. L. Hansen, J. Hartiala et al., “Selected vitamin D metabolic gene variants and risk for autism spectrum disorder in the CHARGE study,” Early Human Development, vol. 91, no. 8, pp. 483–489, 2015.
View at: Publisher Site | Google Scholar
S. Coskun, S. Simsek, M. A. Camkurt, A. Cim, and S. B. Celik, “Association of polymorphisms in the vitamin D receptor gene and serum 25-hydroxyvitamin D levels in children with autism spectrum disorder,” Gene, vol. 588, no. 2, pp. 109–114, 2016.
View at: Publisher Site | Google Scholar
J. Liu, W. Mo, Z. Zhang et al., “Single nucleotide polymorphisms in SLC19A1 and SLC25A9 are associated with childhood autism Spectrum disorder in the Chinese Han population,” Journal of Molecular Neuroscience, vol. 62, no. 2, pp. 262–267, 2017.
View at: Publisher Site | Google Scholar
H. Yu, J. Liu, A. Yang et al., “Lack of association between polymorphisms in Dopa decarboxylase and dopamine receptor-1 genes with childhood autism in Chinese Han population,” Journal of Child Neurology, vol. 31, no. 5, pp. 560–564, 2016.
View at: Publisher Site | Google Scholar
Y. Y. Shi and L. He, “SHEsis, a powerful software platform for analyses of linkage disequilibrium, haplotype construction, and genetic association at polymorphism loci,” Cell Research, vol. 15, no. 2, pp. 97-98, 2005.
View at: Publisher Site | Google Scholar
C. Yang, J. Li, Y. Li et al., “The vitamin D receptor gene ApaI polymorphism is associated with increased risk of renal cell carcinoma in Chinese population,” Scientific Reports, vol. 6, p. 25987, 2016.
View at: Publisher Site | Google Scholar
S. M. Orton, A. P. Morris, B. M. Herrera et al., “Evidence for genetic regulation of vitamin D status in twins with multiple sclerosis,” The American Journal of Clinical Nutrition, vol. 88, no. 2, pp. 441–447, 2008.
View at: Google Scholar
L. Agnello, C. Scazzone, P. Ragonese et al., “Vitamin D receptor polymorphisms and 25-hydroxyvitamin D in a group of Sicilian multiple sclerosis patients,” Neurological Sciences, vol. 37, pp. 261–267, 2016.
View at: Publisher Site | Google Scholar
D. Gezen-Ak, M. Alaylioglu, G. Genc et al., “GC and VDR SNPs and vitamin D levels in Parkinson’s disease: the relevance to clinical features,” Neuromolecular Medicine, vol. 19, no. 1, pp. 24–40, 2017.
View at: Publisher Site | Google Scholar
V. H. Bermudez-Morales, G. Fierros, R. L. Lopez et al., “Vitamin D receptor gene polymorphisms are associated with multiple sclerosis in Mexican adults,” Journal of Neuroimmunology, vol. 306, pp. 20–24, 2017.
View at: Publisher Site | Google Scholar
R. A. Al-Temaimi, A. Al-Enezi, A. Al-Serri, R. Alroughani, and F. Al-Mulla, “The association of vitamin D receptor polymorphisms with multiple sclerosis in a case-control study from Kuwait,” PLoS One, vol. 10, no. 11, article e0142265, 2015.
View at: Publisher Site | Google Scholar
Y. H. Lee, J. H. Kim, and G. G. Song, “Vitamin D receptor polymorphisms and susceptibility to Parkinson’s disease and Alzheimer’s disease: a meta-analysis,” Neurological Sciences, vol. 35, pp. 1947–1953, 2014.
View at: Publisher Site | Google Scholar
N. M. Gatto, K. C. Paul, J. S. Sinsheimer et al., “Vitamin D receptor gene polymorphisms and cognitive decline in Parkinson’s disease,” Journal of the Neurological Sciences, vol. 370, pp. 100–106, 2016.
View at: Publisher Site | Google Scholar
P. Jiang, W. Y. Zhu, X. He et al., “Association between vitamin D receptor gene polymorphisms with childhood temporal lobe epilepsy,” International Journal of Environmental Research and Public Health, vol. 12, no. 11, pp. 13913–13922, 2015.
View at: Publisher Site | Google Scholar
J. Smolders, J. Damoiseaux, P. Menheere, J. W. Tervaert, and R. Hupperts, “Fok-I vitamin D receptor gene polymorphism (rs10735810) and vitamin D metabolism in multiple sclerosis,” Journal of Neuroimmunology, vol. 207, no. 1-2, pp. 117–121, 2009.
View at: Publisher Site | Google Scholar
D. Cierny, J. Michalik, M. Skerenova et al., “ApaI, BsmI and TaqI VDR gene polymorphisms in association with multiple sclerosis in Slovaks,” Neurological Research, vol. 38, no. 8, pp. 678–684, 2016.
View at: Publisher Site | Google Scholar
S. Y. Kang, S. Park, E. Oh et al., “Vitamin D receptor polymorphisms and Parkinson’s disease in a Korean population: revisited,” Neuroscience Letters, vol. 628, pp. 230–235, 2016.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2018 Zengyu Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

2394

Downloads

1271

Citations