Tianlan Lu

Positive association of the Disrupted‐in‐Schizophrenia‐1 gene (DISC1) with schizophrenia in the Chinese han population

Disrupted‐in‐Schizophrenia‐1 (DISC1) is located on 1q42.1, one of the most promising susceptibility loci in schizophrenia linkage studies. A non‐synonymous genetic variation rs821616 (Ser704Cys) in DISC1, has recently been shown to be associated with schizophrenia in family‐based study [Callicott et al. (2005); Proc Natl Acad Sci USA 102: 8627–8632]. In order to further confirm this issue, we examined four single nucleotide polymorphisms (SNPs) in a chromosomal region spanning 42 kb of this gene, namely rs821616, rs821597, rs4658971, and rs843979, in Chinese sample of 313 schizophrenia patients and 317 healthy controls. Our results showed that two SNPs had strong associations with schizophrenia (rs821616: Allele A > T, χ2 = 7.8006, df = 1, P = 0.0052; Genotype, χ2 = 7.7935, df = 2, P = 0.0203; rs821597: Allele A > G, χ2 = 9.5404, df = 1, P = 0.0020; Genotype, χ2 = 12.2780, df = 2, P = 0.0022). When haplotypes were constructed with two, three, and four markers, a number of haplotype combinations, especially those including rs821616 and rs821597, were significantly associated with schizophrenia. Furthermore, there was a strong evidence for association in a four‐marker haplotype analysis (χ2 = 7.686, df = 4, P = 0.005581, corrected P = 0.006199). Although the case‐control and family‐based association studies both suggest that DISC1 gene may play a role in genetic susceptibility to schizophrenia, the risk haplotypic combinations have subtle differences in the two studies. Our findings provide further evidence for DISC1 as a predisposing gene involved in schizophrenia in the Chinese Han Population.

Association of the ENGRAILED 2 (EN2) gene with autism in Chinese Han population

Human ENGRAILED 2 (EN2) gene is localized to 7q36, an autism susceptibility locus. En2 knockout mice display hypoplasia of cerebellum and a decrease in the number of Purkinje cell, which are similar to those reported for individuals with autism. Furthermore, deficits in social behavior were detected in En2−/− mice. Two recent studies have demonstrated that two intronic SNPs (rs1861972, rs1861973) in the EN2 gene are significantly associated with autism. To investigate whether this finding could be replicated in Chinese Han population, we performed the association study between eight single nucleotide polymorphisms (SNPs) of the EN2 gene and autism in 210 Chinese Han trios, using the family‐based association test (FBAT). The present study demonstrated that a preferential transmission of the rs3824068 A‐allele to affected offspring (A > G: Z = 2.399, P = 0.0165). After the Bonferroni correction, this statistical significance of preferential transmission did not remain. However, when haplotypes were constructed with multiple markers, a number of haplotypes including three two‐marker haplotypes, nine three‐marker haplotypes, one four‐marker haplotype, and one six‐marker haplotype, all of which contain the major allele A of rs3824068, displayed significantly associated with autism. These results were still significant after using the permutation method to obtain empirical P values. Thus, our data provide evidence that the EN2 gene may be implicated in the predisposition to autism in the Chinese Han population.

Association of the neuropilin-2 (NRP2) gene polymorphisms with autism in Chinese Han population.

Autism is a pervasive neurodevelopmental disorder, with a significant role of genetic factors in its development. The neuropilin‐2 (NRP2) gene is localized to 2q34, an autism susceptibility locus. NRP2 has been demonstrated to both guide axons and to control neuronal migration in the central nervous system. It has been reported that NRP2 may be required in vivo for sorting migrating cortical and striatal interneurons to their correct destination. We examine the association between the NRP2 gene and autism using a cohort of 169 Chinese Han family trios. Four single nucleotide polymorphisms (SNPs) were genotyped by the polymerase chain reaction‐based restriction fragment length polymorphism (PCR‐RFLP) analyses. The transmission disequilibrium tests (TDT) of SNPs and haplotype association were carried out using the TDTPHASE program. We found significant genetic association between autism and two of the SNPs of the NRP2 gene (rs849578: P = 0.017, rs849563: P = 0.027), as well as specific haplotypes, especially those formed by rs849563. Furthermore, haplotypes constructed with all markers showed significant excess transmission in both global and individual haplotype analyses (P = 0.004 and 0.017, respectively). The polymorphisms in the NRP2 gene are associated with autism, implying that the NRP2 gene may render individuals to be predisposed to autism.

Association of DAOA polymorphisms with schizophrenia and clinical symptoms or therapeutic effects

The present study examined the correlation between variants in the d-amino acid oxidase activator (DAOA) locus and clinical symptoms and response to antipsychotics in schizophrenia. Case-control analysis and the family-based association test (FBAT) were performed to investigate whether four single nucleotide polymorphisms (SNPs) at DAOA gene are associated with schizophrenia. The association between the DAOA risk haplotype and clinical symptoms were examined by the positive and negative syndrome scale (PANSS) and the brief psychiatric rating scale (BPRS). Our findings showed that the SNP rs947267 was significantly associated with schizophrenia in both case control and familial trio samples (A>C, chi(2)=8.36, p=0.004; Z=2.335, p=0.019), as well as with specific haplotypes, in particular those formed by the A allele of rs947267. In addition, the risk haplotype AAG was significantly correlated with negative, depression and cognitive impairment factors of PANSS, even with the BPRS change scores after 6-week treatment of atypical antipsychotic drugs (p<0.05). These results support the hypothesis that variations in DAOA may play a role in schizophrenia and clinical characteristics.

Association study of SHANK3 gene polymorphisms with autism in Chinese Han population

BackgroundAutism, a heterogeneous disease, is described as a genetic psychiatry disorder. Recently, abnormalities at the synapse are supposed to be important for the etiology of autism.SHANK3 (SH3 and multiple ankyrin repeat domains protein) gene encodes a master synaptic scaffolding protein at postsynaptic density (PSD) of excitatory synapse. Rare mutations and copy number variation (CNV) evidence suggested SHANK3 as a strong candidate gene for the pathogenesis of autism.MethodsWe performed an association study between SHANK3 gene polymorphisms and autism in Chinese Han population. We analyzed the association between five single nucleotide polymorphisms (SNPs) of the SHANK3 gene and autism in 305 Chinese Han trios, using the family based association test (FBAT). Linkage disequilibrium (LD) analysis showed the presence of LD between pairwise markers across the locus. We also performed mutation screening for the rare de novo mutations reported previously.ResultsNo significant evidence between any SNPs of SHANK3 and autism was observed. We did not detect any mutations described previously in our cohort.ConclusionWe suggest that SHANK3 might not represent a major susceptibility gene for autism in Chinese Han population.

Evidence for association between Disrupted-in-schizophrenia 1 (DISC1) gene polymorphisms and autism in Chinese Han population: a family-based association study

BackgroundDisrupted-in-Schizophrenia 1 (DISC1) gene is one of the most promising candidate genes for major mental disorders. In a previous study, a Finnish group demonstrated that DISC1 polymorphisms were associated with autism and Asperger syndrome. However, the results were not replicated in Korean population. To determine whether DISC1 is associated with autism in Chinese Han population, we performed a family-based association study between DISC1 polymorphisms and autism.MethodsWe genotyped seven tag single nucleotide polymorphisms (SNPs) in DISC1, spanning 338 kb, in 367 autism trios (singleton and their biological parents) including 1,101 individuals. Single SNP association and haplotype association analysis were performed using the family-based association test (FBAT) and Haploview software.ResultsWe found three SNPs showed significant associations with autism (rs4366301: G > C, Z = 2.872, p = 0.004; rs11585959: T > C, Z = 2.199, p = 0.028; rs6668845: A > G, Z = 2.326, p = 0.02). After the Bonferroni correction, SNP rs4366301, which located in the first intron of DISC1, remained significant. When haplotype were constructed with two-markers, three haplotypes displayed significant association with autism. These results were still significant after using the permutation method to obtain empirical p values.ConclusionsOur study provided evidence that the DISC1 may be the susceptibility gene of autism. It suggested DISC1 might play a role in the pathogenesis of autism.

Schizophrenia Related Variants in CACNA1C also Confer Risk of Autism.

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders with a strong genetic component. Many lines of evidence indicated that ASD shares common genetic variants with other psychiatric disorders (for example, schizophrenia). Previous studies detected that calcium channels are involved in the etiology of many psychiatric disorders including schizophrenia and autism. Significant association between CACNA1C (calcium channel, voltage-dependent, L type, alpha 1C subunit) and schizophrenia was detected. Furthermore, rare mutation in CACNA1C is suggested to cause Timothy syndrome, a multisystem disorder including autism-associated phenotype. However, there is no evidence for association between CACNA1C and autism in Chinese Han population. To investigate the association between single nucleotide polymorphisms (SNP) in CACNA1C and autism, we first performed a family-based association study between eighteen SNPs in CACNA1C and autism in 239 trios. All SNPs were genotyped by using Sequenom genotyping platform. Two SNPs (rs1006737 and rs4765905) have a trend of association with autism. To further confirm the association between these two SNPs with autism, we expanded the sample size to 553 trios by adding 314 trios. Association analyses for SNPs and haplotype were performed by using family-based association test (FBAT) and Haploview software. Permutation tests were used for multiple testing corrections of the haplotype analyses (n=10,000). The significance level for all statistical tests was two-tailed (p<0.05). The results demonstrated that G allele of rs1006737 and G allele of rs4765905 showed a preferential transmission to affected offspring in 553 trios (p=0.035). Haplotype analyses showed that two haplotypes constructed from rs1006737 and rs4765905 were significantly associated with autism (p=0.030, 0.023, respectively; Global p=0.046). These results were still significant after permutation correction (n=10,000, p=0.027). Our research suggests that CACNA1C might play a role in the genetic etiology of autism in Chinese Han population.

Further evidence for genetic association of CACNA1C and schizophrenia: New risk loci in a Han Chinese population and a meta-analysis

CACNA1C (12p13.3) has been implicated as a susceptibility gene for schizophrenia by several replicated genome wide association studies. While these results have been consistent among studies in European populations, the findings in East Asian populations have varied. To test whether CACNA1C is a risk gene for schizophrenia, we conducted a case-control study in 5897 schizophrenic patients and 6323 healthy control subjects selected from Han Chinese population. Our study replicated the positive associations of rs1006737 (P=0.0108, OR=1.16, 95% CI: 1.03-1.29) and rs1024582 (P=0.0062, OR=1.18, 95% CI: 1.05-1.33), and identified a novel risk locus, rs2007044 (P=0.0053, OR=1.08, 95% CI: 1.02-1.14). A meta-analysis of rs1006737 combining our study and previous studies was conducted in a total of 8222 schizophrenia cases and 24,661 healthy controls. In the meta-analysis, the association between rs1006737 and schizophrenia remained significant (OR=1.14, 95% CI: 1.07-1.22, P=0.0001). Stratified analysis showed no heterogeneity between East Asian and European ancestries (χ(2)[1]=0.07, P=0.795), and the difference in pooled ORs between ancestries was not significant (Z=0.25, P=0.801). Our results provide further support for associations of rs1006737 and rs1024582 with schizophrenia, identify a new risk locus rs2007044 in a Han Chinese population, and further establish CACNA1C as an important susceptibility gene for the disease across world populations.

Sequencing ASMT Identifies Rare Mutations in Chinese Han Patients with Autism

Melatonin is involved in the regulation of circadian and seasonal rhythms and immune function. Prior research reported low melatonin levels in autism spectrum disorders (ASD). ASMT located in pseudo-autosomal region 1 encodes the last enzyme of the melatonin biosynthesis pathway. A previous study reported an association between ASD and single nucleotide polymorphisms (SNPs) rs4446909 and rs5989681 located in the promoter of ASMT. Furthermore, rare deleterious mutations were identified in a subset of patients. To investigate the association between ASMT and autism, we sequenced all ASMT exons and its neighboring region in 398 Chinese Han individuals with autism and 437 healthy controls. Although our study did not detect significant differences of genotypic distribution and allele frequencies of the common SNPs in ASMT between patients with autism and healthy controls, we identified new rare coding mutations of ASMT. Among these rare variants, 4 were exclusively detected in patients with autism including a stop mutation (p.R115W, p.V166I, p.V179G, and p.W257X). These four coding variants were observed in 6 of 398 (1.51%) patients with autism and none in 437 controls (Chi-Square test, Continuity Correction p = 0.032, two-sided). Functional prediction of impact of amino acid showed that p.R115W might affect protein function. These results indicate that ASMT might be a susceptibility gene for autism. Further studies in larger samples are needed to better understand the degree of variation in this gene as well as to understand the biochemical and clinical impacts of ASMT/melatonin deficiency.

A case-control association study of NRXN1 polymorphisms with schizophrenia in Chinese Han population

BackgroundRecent research has implicated that mutations in the neurexin-1 (NRXN1) gene on chromosome 2p16.3 might play a role in schizophrenia, autism, and nicotine dependence. In order to explore the association of NRXN1 polymorphisms with schizophrenia, we made a case-control association study in Chinese Han population.MethodsWe examined six tag single nucleotide polymorphisms (SNPs) spanning 116.7 kb of NRXN1 in 768 schizophrenic patients and 738 healthy control subjects. The association of NRXN1 polymorphisms with schizophrenia and the age-at-onset of this disease were explored.ResultsOur results showed that four SNPs of NRXN1 gene were significantly associated with schizophrenia (rs10490168: G > A, p = 0.017; rs2024513: A > G, p = 0.006; rs13382584: T > C, p = 0.009; and rs1558852: G > A, p = 0.031). Furthermore, the association of SNP rs2024513 with schizophrenia remained significance after the Bonferroni correction. Haplotypes consisting of above six SNPs also showed significantly associated with schizophrenia (global chi-square = 14.725, p = 0.022). A protective haplotype AGTGCA remained associated with schizophrenia, even after 10,000 permutation tests (empirical p-value = 0.043). However, we did not find any association with age-at-onset of schizophrenia with NRXN1 polymorphisms.ConclusionsOur findings suggest that NRXN1 might represent a major susceptibility gene for schizophrenia in Chinese Han population.