The authors have declared that no competing interests exist.
Conceived and designed the experiments: CYW ZQX. Performed the experiments: YJW YTY. Analyzed the data: HL CLT FL. Contributed reagents/materials/analysis tools: CLT FL. Wrote the paper: YJW YTY.
This study aimed to investigate the association of galanin (GAL) gene and the development of depression in the Chinese Han population.
A total of 700 patients with depression who met the diagnostic criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and 673 healthy controls were used in this study. Ligase detection reactions were performed on 10 selected single nucleotide polymorphism (SNP) sites in the GAL gene. A series of statistical methods were carried out to investigate the correlation between the GAL gene SNP and the patient susceptibility to depression.
The SNPs of rs694066 in the GAL gene showed a positive correlation with MDD. Compared with the healthy controls, lower frequency of G/G genotype and higher frequency of A/G genotype were observed in rs694066 in MDD patients, a lower frequency of G-allele and higher frequency of A-allele were observed in rs694066. These correlations were more pronounced in the 376 female patients and 360 female control subjects than in the 324 male patients and 313 healthy male subjects.
This study investigated the relationship between the GAL gene SNP and the susceptibility to depression in the Chinese Han population. The findings clearly indicate that the GAL gene polymorphism is closely correlated to the incidence of depression in the Chinese Han female patients.
Major depressive disorder (MDD) is a common and debilitating condition with pervasive impact on the quality of life for both patients and their families
This study aimed to investigate the association of single nucleotide polymorphism (SNP) of the GAL gene with the risk of developing MDD in the Chinese Han population.
This study was approved by the Research Ethics Committee of the Capital Medical University Hospital and written informed consent was obtained from each of the participants or guardians. The objective and procedures of this study were explained to all of the subjects and the patient’s guardians. Healthy control subjects and some patients who could read the consent signed the informed consent forms themselves. Some patients’ guardians consented to sign the informed consent forms on behalf of the participants whose capacity to consent was compromised. All potential participants who declined to participate or otherwise did not participate were eligible for treatment and were not disadvantaged in any other way by not participating in the study.
Seven hundred patients (324 men and 376 women; mean age 40±14.9 years) diagnosed with MDD by independent physicians blind to the study design using the criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) were recruited. Six hundred and seventy-three healthy volunteers (313 men and 360 women; mean age 41.9±17.2 years) were included as controls. All subjects were screened by two trained psychiatrists using the DSM-IV Axis I disorder (SCID-I/P). Sex was not limited and 18< age <60. MDD patients had 2 or more times of depressive episode and without Electroconvulsive therapy (ECT) in half a year and without the use of antidepressants treatment in 1 month. Healthy controls had no mental disease and family history and HAMD-17≤7. Patients who had a history of alcohol or drug dependence, or who had a full-scale IQ of less than 80 measured by the Wechsler Intelligence Scale were excluded. The onset age of patients was 30.36±12.44 years, the duration of illness were 54.20±82.84 months and the average years of education were 12.04±3.04 years.
Genomic DNA was extracted from whole blood samples using a genomic DNA Purification Kit (TAKARA). Genotyping for GAL polymorphisms was conducted by polymerase chain reaction (PCR) followed by ligase detection reaction (LDR). Fragments of the GAL gene, each harboring one of the SNP sites listed in
LDRs were performed on a MJ PCT-200 Gradient thermal cycler in 20 μL of buffer containing 20 mM Tris–HCl (pH 7.6), 10 mM MgCl2, 100 mM KCl, 10 mM DTT, 1 mM EDTA, 1mM NAD+, 12.5 nM of each probe, 1 μL PCR product, and 0.1 mM DNA ligase. The reaction included an initial incubation at 95°C for 2 min and then cycling for 35 cycles at 94°C for 30 s and 60°C for 2 min. After addition of 0.5 mL 0.5 mM EDTA to stop the reaction, the products (1 μL) were mixed with an equal volume of ABI GS-500 ROX (a fluorescent labeled molecular weight standard) and deionized formamide. The mixture was denatured at 95°C for 2 min, chilled on ice rapidly, loaded on a 5% polyacrylamide and 5 M urea gel, and electrophoresed for 2.5 h at 3000V (377 DNA Prism Sequencer; Applied Biosystems). Genemapper software was used to analyze the ligation products.
All analyses were performed using SPSS software program Version 16.0 for Windows (SPSS Institute Inc., Chicago, IL, USA). Chi-square test was used to analyze the differences in genotypic frequency distributions of GAL polymorphisms between the MDD cases and the control subjects and Hardy-Weinberg equilibrium test was performed to determine the departure. The polymorphism data were stratified on the basis of sex. Power analyses were completed using the Genetics Power Calculator (
According to the results of the test, all alleles and genotypic of the selected ten GAL SNPs were in Hardy-Weinberg equilibrium (
The power for the overall samples was 92.23% with the genotype relative risk of 2.2 at a nominal
The relationship between GAL SNPs and the susceptibility of MDD were analyzed (
SNPs | Group | Allele1 (freq) | Allele2 (freq) | OR | 95%CI | ?2 | |
rs2510387 | MDD | A (0.867) | G (0.133) | 0.943 | 0.752∼1.183 | 0.255 | 0.613 |
Con | 0.874 | 0.126 | |||||
rs2513297 | MDD | G (0.868) | A (0.132) | 1.104 | 0.877∼1.389 | 0.712 | 0.399 |
Con | 0.879 | 0.121 | |||||
rs2187331 | MDD | A (0.876) | G (0.124) | 0.940 | 0.748∼1.182 | 0.279 | 0.5977 |
Con | 0.869 | 0.131 | |||||
rs948854 | MDD | A (0.862) | G (0.138) | 0.860 | 0.696∼1.063 | 1.939 | 0.164 |
Con | 0.845 | 0.155 | |||||
rs2097042 | MDD | A (0.840) | G (0.160) | 1.026 | 0.833∼1.264 | 0.058 | 0.809 |
Con | 0.843 | 0.157 | |||||
rs4432027 | MDD | T (0.854) | C (0.146) | 1.149 | 0.930∼1.418 | 1.662 | 0.197 |
Con | 0.836 | 0.164 | |||||
rs694066 | MDD | G (0.944) | A (0.056) | 2.216 | 1.472∼3.337 | 15.215 | 9.7E-5 |
Con | 0.974 | 0.026 | |||||
rs1546309 | MDD | T (0.835) | C (0.165) | 1.141 | 0.932∼1.395 | 1.637 | 0.201 |
Con | 0.816 | 0.184 | |||||
rs3136540 | MDD | C (0.846) | T (0.154) | 0.839 | 0.683∼1.031 | 2.798 | 0.094 |
Con | 0.822 | 0.178 | |||||
rs1042577 | MDD | C (0.786) | T (0.214) | 0.936 | 0.779∼1.124 | 0.595 | 0.440 |
Con | 0.774 | 0.226 |
SNPs | Group | Genotype1 (freq) | Genotype2 (freq) | Genotype3 (freq) | ?2 | |
rs2510387 | MDD | A/A (0.747) | A/G (0.242) | G/G(0.012) | 0.632 | 0.729 |
Con | 0.762 | 0.224 | 0.014 | |||
rs2513297 | MDD | G/G(0.754) | A/G (0.228) | A/A (0.018) | 1.074 | 0.584 |
Con | 0.777 | 0.205 | 0.019 | |||
rs2187331 | MDD | A/A (0.756) | A/G (0.227) | G/G (0.018) | 1.144 | 0.565 |
Con | 0.773 | 0.205 | 0.022 | |||
rs948854 | MDD | A/A (0.694) | A/G (0.296) | G/G (0.010) | 4.529 | 0.104 |
Con | 0.737 | 0.247 | 0.015 | |||
rs2097042 | MDD | A/A (0.705) | A/G (0.278) | G/G (0.018) | 1.201 | 0.549 |
Con | 0.706 | 0.268 | 0.026 | |||
rs4432027 | MDD | T/T (0.692) | T/C (0.289) | C/C (0.019) | 3.405 | 0.182 |
Con | 0.732 | 0.245 | 0.023 | |||
rs694066 | MDD | G/G (0.887) | A/G (0.113) | 15.911 | 6.73E-005 | |
Con | 0.947 | 0.053 | ||||
rs1546309 | MDD | T/T (0.662) | T/C (0.308) | C/C (0.030) | 1.692 | 0.429 |
Con | 0.695 | 0.280 | 0.025 | |||
rs3136540 | MDD | C/C (0.674) | C/T (0.297) | T/T (0.030) | 2.930 | 0.231 |
Con | 0.713 | 0.267 | 0.020 | |||
rs1042577 | MDD | C/C (0.598) | C/T (0.354) | T/T (0.048) | 1.051 | 0.591 |
Con | 0.610 | 0.353 | 0.037 |
When the data on SNPs and the incidence of MDD were analyzed on the basis of gender, it turned out that the 376 female MDD patients and 360 female healthy control subjects had a significant lower frequency of genotype G/G in rs694066, a significant higher frequency of genotype A/G, a lower frequency of the G-allele and a higher frequency of A-allele in rs694066. In contrast, no SNP showed a significant correlation with MDD in the male subjects. (
sex | Group | Allele1 (freq) | Allele2 (freq) | OR | 95%CI | ?2 | ||
female (376) | MDD | G (0.938) | A (0.062) | 2.647 | 1.505–4.656 | 12.243 | 0.0005 | 0.005 |
Con | 0.975 | 0.025 | ||||||
male (324) | MDD | G (0.951) | A (0.049) | 1.788 | 0.982–3.254 | 3.704 | 0.054 | 0.54 |
Con | 0.972 | 0.028 |
Sex | Group | Genotype1 (freq) | Genotype2 (freq) | ?2 | ||
female (376) | MDD | G/G (0.875) | A/G (0.125) | 12.838 | 0.0003 | 0.003 |
Con | 0.951 | 0.049 | ||||
male (324) | MDD | G/G (0.901) | A/G (0.099) | 3.862 | 0.050 | 0.50 |
Con | 0.944 | 0.056 |
Linkage disequilibrium analysis was performed on the 10 identified GAL SNPs by using the Haploview software. As shown in
In this study, we detected 10 SNPs in the GAL gene in 700 patients with MDD and 673 healthy controls by using ligase detection reaction. All subjects were Chinese Han. The psychiatric diagnosis was made according to the criteria of DSM-IV. Our analyses showed a significant correlation between GAL gene polymorphisms of rs694066 and the susceptibility of MDD. More interestingly, this correlation was gender-dependent: a positive correlation between GAL SNPs and the incidence of MDD was observed only in female patients but not in male patients. Recent studies have demonstrated that much more women than men suffered MDD
A large number of studies have shown that the release disturbance of 5-hydroxytryptamine (5-HT) and norepinephrine (NE) might be associated with an increased susceptibility to depression
Similar results have been also demonstrated in two other independent studies of depression and panic disorders in Sweden, in which the GAL gene polymorphism site of rs948854 showed a high degree of correlation with the severity of symptoms of female patients with depression
In conclusion, this study has demonstrated a positive correlation between the SNP site of rs694066 in the GAL gene and the susceptibility of the female but not male Chinese Han patients to depression. We have also demonstrated that patients with MDD have a lower frequency of G-allele of rs694066 and a higher A-allele. However, there are some limitations in this study. First, the sample size is not large enough. Second, the chosen SNPs may not represent the whole gene of GAL. Therefore, further functional studies involving a larger sample size are warranted.
Primers and Probes Used in the Polymerase Chain Reaction–Ligase Detection Reaction Protocol.
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GAL SNPs detection and HWE test from Chinese Han population.
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Haplotype correlation analysis of depression.
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We warmly thank all of the participants and families for their contribution to our study.