Association analysis of polymorphic CGG repeat in 5' UTR of the reelin and VLDLR genes with schizophrenia

A Homozygous Dab1-/- Is a Potential Novel Cause of Autosomal Recessive Congenital Anomalies of the Mice Kidney and Urinary Tract

This study aimed to explore morphology changes in the kidneys of Dab1^−/− (yotari) mice, as well as expression patterns of reelin, NOTCH2, LC3B, and cleaved caspase3 (CASP3) proteins, as potential determinants of normal kidney formation and function. We assumed that Dab1 functional inactivation may cause disorder in a wide spectrum of congenital anomalies of the kidney and urinary tract (CAKUT). Animals were sacrificed at postnatal days P4, P11, and P14. Paraffin-embedded kidney tissues were sectioned and analyzed by immunohistochemistry using specific antibodies. Kidney specimens were examined by bright-field, fluorescence, and electron microscopy. Data were analyzed by two-way ANOVA and t-tests. We noticed that yotari kidneys were smaller in size with a reduced diameter of nephron segments and thinner cortex. TEM microphotographs revealed foot process effacement in the glomeruli (G) of yotari mice, whereas aberrations in the structure of proximal convoluted tubules (PCT) and distal convoluted tubules (DCT) were not observed. A significant increase in reelin expression, NOTCH2, LC3B and cleaved CASP3 proteins was observed in the glomeruli of yotari mice. Renal hypoplasia in conjunction with foot process effacement and elevation in the expression of examined proteins in the glomeruli revealed CAKUT phenotype and loss of functional kidney tissue of yotari.

Dorsal Forebrain-Specific Deficiency of Reelin-Dab1 Signal Causes Behavioral Abnormalities Related to Psychiatric Disorders

Reelin-Dab1 signaling is involved in brain development and neuronal functions. The abnormalities in the signaling through either reduction of Reelin and Dab1 gene expressions or the genomic mutations in the brain have been reported to be associated with psychiatric disorders. However, it has not been clear if the deficiency in Reelin-Dab1 signaling is responsible for symptoms of the disorders. Here, to examine the function of Reelin-Dab1 signaling in the forebrain, we generated dorsal forebrain-specific Dab1 conditional knockout mouse (Dab1 cKO) and performed a behavioral test battery on the Dab1 cKO mice. Although conventional Dab1 null mutant mice exhibit cerebellar atrophy and cerebellar ataxia, the Dab1 cKO mice had normal cerebellum and showed no motor dysfunction. Dab1 cKO mice exhibited behavioral abnormalities, including hyperactivity, decreased anxiety-like behavior, and impairment of working memory, which are reminiscent of symptoms observed in patients with psychiatric disorders such as schizophrenia and bipolar disorder. These results suggest that deficiency of Reelin-Dab1 signal in the dorsal forebrain is involved in the pathogenesis of some symptoms of human psychiatric disorders.

Is treatment-resistant schizophrenia categorically distinct from treatment-responsive schizophrenia? a systematic review

BACKGROUND

Schizophrenia is a highly heterogeneous disorder, and around a third of patients are treatment-resistant. The only evidence-based treatment for these patients is clozapine, an atypical antipsychotic with relatively weak dopamine antagonism. It is plausible that varying degrees of response to antipsychotics reflect categorically distinct illness subtypes, which would have significant implications for research and clinical practice. If these subtypes could be distinguished at illness onset, this could represent a first step towards personalised medicine in psychiatry. This systematic review investigates whether current evidence supports conceptualising treatment-resistant and treatment-responsive schizophrenoa as categorically distinct subtypes.

METHOD

A systematic literature search was conducted, using PubMed, EMBASE, PsycInfo, CINAHL and OpenGrey databases, to identify all studies which compared treatment-resistant schizophrenia (defined as either a lack of response to two antipsychotic trials or clozapine prescription) to treatment-responsive schizophrenia (defined as known response to non-clozapine antipsychotics).

RESULTS

Nineteen studies of moderate quality met inclusion criteria. The most robust findings indicate that treatment-resistant patients show glutamatergic abnormalities, a lack of dopaminergic abnormalities, and significant decreases in grey matter compared to treatment-responsive patients. Treatment-resistant patients were also reported to have higher familial loading; however, no individual gene-association study reported their findings surviving correction for multiple comparisons.

CONCLUSIONS

Tentative evidence supports conceptualising treatment-resistant schizophrenia as a categorically different illness subtype to treatment-responsive schizophrenia. However, research is limited and confirmation will require replication and rigorously controlled studies with large sample sizes and prospective study designs.

Evaluating the relationship between reelin gene variants (rs7341475 and rs262355) and schizophrenia: A meta-analysis

Studies have suggested that reelin (RELN) polymorphism was associated with the susceptibility of schizophrenia (SZ), but the results remained controversial. Thus, we conducted this meta-analysis to determine whether RELN variants (rs7341475 and rs262355) were associated with SZ risk. Studies were identified through retrieving Web of Science, PubMed and Embase databases from inception to May 2015. The genotype data were extracted to calculate the odds ratios (ORs) and 95% confidence intervals (CIs). For rs7341475, five studies with 4741 SZ patients and 10075 controls are included and the results indicate that carriage of A allele is associated with decreased SZ risk in dominant genetic model (OR=0.90, 95%CI=0.83-0.98) and additive model (OR=0.90, 95% CI=0.84-0.97). Subgroup analysis indicates that the association between rs7341475 and SZ is only significant in Caucasian. For rs262355, four studies with 2017 SZ patients and 3274 controls are included, the results demonstrate that carriage of A allele is associated with increased risk of SZ only in Caucasian (dominant model: OR=1.17, 95%CI=1.01-1.37; additive model OR=1.13, 95%CI=1.02-1.27). This meta-analysis suggests that rs7341475 (A/G) and rs262355 (A/T) polymorphisms in RELN gene are inversely associated with SZ risk.

A literature search tool for intelligent extraction of disease-associated genes

OBJECTIVE

To extract disorder-associated genes from the scientific literature in PubMed with greater sensitivity for literature-based support than existing methods.

METHODS

We developed a PubMed query to retrieve disorder-related, original research articles. Then we applied a rule-based text-mining algorithm with keyword matching to extract target disorders, genes with significant results, and the type of study described by the article.

RESULTS

We compared our resulting candidate disorder genes and supporting references with existing databases. We demonstrated that our candidate gene set covers nearly all genes in manually curated databases, and that the references supporting the disorder-gene link are more extensive and accurate than other general purpose gene-to-disorder association databases.

CONCLUSIONS

We implemented a novel publication search tool to find target articles, specifically focused on links between disorders and genotypes. Through comparison against gold-standard manually updated gene-disorder databases and comparison with automated databases of similar functionality we show that our tool can search through the entirety of PubMed to extract the main gene findings for human diseases rapidly and accurately.

The involvement of Reelin in neurodevelopmental disorders

Reelin is a glycoprotein that serves important roles both during development (regulation of neuronal migration and brain lamination) and in adulthood (maintenance of synaptic function). A number of neuropsychiatric disorders including autism, schizophrenia, bipolar disorder, major depression, Alzheimer's disease and lissencephaly share a common feature of abnormal Reelin expression in the brain. Altered Reelin expression has been hypothesized to impair neuronal connectivity and synaptic plasticity, leading ultimately to the cognitive deficits present in these disorders. The mechanisms for abnormal Reelin expression in some of these disorders are currently unknown although possible explanations include early developmental insults, mutations, hypermethylation of the promoter for the Reelin gene (RELN), miRNA silencing of Reelin mRNA, FMRP underexpression and Reelin processing abnormalities. Increasing Reelin expression through pharmacological therapies may help ameliorate symptoms resulting from Reelin deficits. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.

Association study of RELN polymorphisms with schizophrenia in Han Chinese population

Schizophrenia (SZ) is a common and complex psychiatric disorder with a strong genetic component. Previous research suggests that mutations altering genes in neurodevelopmental pathways contribute to SZ. Reelin gene (RELN) maps to chromosome 7q22.1, the encoded protein plays a pivotal role in guiding neuronal migration, lamination and connection during embryonic brain development. Several reports had indicated that reduced RELN expression is associated with human mental illnesses such as SZ, mood disorders and autism. In this study, case-control association analyses were performed in the Han Chinese population to determine if the RELN gene is a susceptibility gene for SZ. Thirty-seven single nucleotide polymorphisms (SNPs) were genotyped in 528 paranoid SZ patients and 528 control subjects. A significant association was found between rs12705169 and SZ (p=0.001). Moreover, the haplotypes constructed from five SNPs showed significant differences between cases and controls (p=0.041). When subjects were divided by gender, rs12705169 remained significant difference only in females (OR=0.24, 95%CI=0.14-0.40 for CC and OR=0.40, 95%CI=0.27-0.58 for AC), both in the allele and genotype (p=0.0001 for both). This study describes a positive association between RELN and SZ in the Han Chinese population, and provides genetic evidence to support the gender difference of SZ.

Does subtle disturbance of neuronal migration contribute to schizophrenia and other neurodevelopmental disorders? Potential genetic mechanisms with possible treatment implications

Pathways associated with genes that regulate neuronal migration by influencing the function of microtubules in the developing fetal brain may be interfered with as part of the "first-hit" of schizophrenia. In the fully-developed brain, these same pathways that impact microtubule function mediate at least some aspects of experience-dependent plasticity, which may also be impaired in schizophrenia. Whereas severe presentations of "lissencephaly" are associated with mutations and deletions of DISC1, LIS1 and the gene for the very low-density lipoprotein receptor, genetic variations of these loci are good candidate schizophrenia genes. Importantly, in the fully-developed brain, there is a possibility that at least some of the consequences of these disturbed genetic pathways that adversely affect microtubule function may be "bypassed" or mitigated.

Polymorphisms in genes involved in neurodevelopment may be associated with altered brain morphology in schizophrenia: preliminary evidence

An abnormality in neurodevelopment is one of the most robust etiologic hypotheses in schizophrenia (SZ). There is also strong evidence that genetic factors may influence abnormal neurodevelopment in the disease. The present study evaluated in SZ patients, whose brain structural data had been obtained with magnetic resonance imaging (MRI), the possible association between structural brain measures, and 32 DNA polymorphisms, located in 30 genes related to neurogenesis and brain development. DNA was extracted from peripheral blood cells of 25 patients with schizophrenia, genotyping was performed using diverse procedures, and putative associations were evaluated by standard statistical methods (using the software Statistical Package for Social Sciences - SPSS) with a modified Bonferroni adjustment. For reelin (RELN), a protease that guides neurons in the developing brain and underlies neurotransmission and synaptic plasticity in adults, an association was found for a non-synonymous polymorphism (Val997Leu) with left and right ventricular enlargement. A putative association was also found between protocadherin 12 (PCDH12), a cell adhesion molecule involved in axonal guidance and synaptic specificity, and cortical folding (asymmetry coefficient of gyrification index). Although our results are preliminary, due to the small number of individuals analyzed, such an approach could reveal new candidate genes implicated in anomalous neurodevelopment in schizophrenia.

Association analysis of schizophrenia on 18 genes involved in neuronal migration: MDGA1 as a new susceptibility gene

Several lines of evidence support the theory of schizophrenia (SZ) being a neurodevelopmental disorder. The structural, cytoarchitectural and functional brain abnormalities reported in patients with SZ, might be due to aberrant neuronal migration, since the final position of neurons affects neuronal function, morphology, and formation of synaptic connections. We have investigated the putative association between SZ and gene variants engaged in the neuronal migration process, by performing an association study on 839 cases and 1,473 controls of Scandinavian origin. Using a gene-wide approach, tagSNPs in 18 candidate genes have been genotyped, with gene products involved in the neuron-to-glial cell adhesion, interactions with the DISC1 protein and/or rearrangements of the cytoskeleton. Of the 289 markers tested, 19 markers located in genes MDGA1, RELN, ITGA3, DLX1, SPARCL1, and ASTN1, attained nominal significant P-values (P < 0.05) in either a genotypic or allelic association test. All of these genes, except transcription factor DLX1, are involved in the adhesion between neurons and radial glial cells. Eight markers obtained nominal significance in both tests, and were located in intronic or 3'UTR regions of adhesion molecule MDGA1 and previously reported SZ candidate RELN. The most significant result was attained for MDGA1 SNP rs9462341 (unadjusted association results: genotypic P = 0.00095; allelic P = 0.010). Several haplotypes within MDGA1, RELN, ITGA3, and ENAH were nominally significant. Further studies in independent samples are needed, including upcoming genome wide association study results, but our data suggest that MDGA1 is a new SZ susceptibility gene, and that altered neuronal migration is involved in SZ pathology.

The association analysis of RELN and GRM8 genes with autistic spectrum disorder in Chinese Han population

The region on chromosome 7q stands out as the region of suggestive linkage to aetiology of autism with the greatest concordance in many independent genome-wide scans. RELN and GRM8, the two genes selected in this study, are located within this region. The protein products of both genes are considered to play a pivotal role in the development of the central nervous system. In addition, biochemical and neuroanatomical data indicated that RELN and GRM8 genes are likely involved in the pathogenesis of autistic disorder. Therefore, both RELN and GRM8 genes are considered to be not only the positional but also the functional candidate genes to autism for association research. In this study, we genotyped 12 single nucleotide polymorphisms (SNPs) located within the RELN and GRM8 genes in 213 children with autistic spectrum disorder (ASD) and 160 controls. A significant genetic association between SNP2 (located in intron 59 of RELN) and ASD was observed, and the log-additive model was accepted as the best inheritance model fitting this data (OR: 0.72, 95% CI: 0.54-0.97, P = 0.03). Haplotype-specific association analysis revealed that the result was consistent with the individual SNP study; the combination of SNP1/SNP2/SNP3/SNP4 which are in strong linkage disequilibrium (LD) (D' > 0.75) showed significant association with ASD (P = 0.027). Neither the single SNP nor the haplotype analysis showed significant association between ASD and the markers of GRM8 gene. Hence, our study suggested the possible involvement of RELN gene in the susceptibility to ASD. Future replications are warranted before definitive conclusion can be drawn.

Genome-wide association identifies a common variant in the reelin gene that increases the risk of schizophrenia only in women

Sex differences in schizophrenia are well known, but their genetic basis has not been identified. We performed a genome-wide association scan for schizophrenia in an Ashkenazi Jewish population using DNA pooling. We found a female-specific association with rs7341475, a SNP in the fourth intron of the reelin (RELN) gene (p = 2.9 x 10(-5) in women), with a significant gene-sex effect (p = 1.8 x 10(-4)). We studied rs7341475 in four additional populations, totaling 2,274 cases and 4,401 controls. A significant effect was observed only in women, replicating the initial result (p = 2.1 x 10(-3) in women; p = 4.2 x 10(-3) for gene-sex interaction). Based on all populations the estimated relative risk of women carrying the common genotype is 1.58 (p = 8.8 x 10(-7); p = 1.6 x 10(-5) for gene-sex interaction). The female-specific association between RELN and schizophrenia is one of the few examples of a replicated sex-specific genetic association in any disease.

Potential genetic variants in schizophrenia: a Bayesian analysis

A number of different gene polymorphisms have been found to dispose for the development of schizophrenia. However, no single gene polymorphism is sufficient for the precipitation of schizophrenia. Swedish psychosis patients (n=103) and control subjects (n=89) were analyzed for 36 single nucleotide polymorphisms in 30 candidate genes for schizophrenia. Evidence of association was analyzed with Bayesian statistical methods. Variants in the genes coding for dopamine-D2 receptor, brain-derived neurotrophic factor (BDNF), neuropeptide Y (NPY), neuregulin 1, reelin and synapsin 3 showed association with schizophrenia, although few subjects were found in the minority allele for the two latter variants. The six gene variants, all with suspected connection to schizophrenia, were found to be risk factors when considered in combination, but not separately. The results indicate that the Bayesian statistical method gives additional possibilities in the search for risk factors for schizophrenia or other complex disorders.

Reelin gene polymorphisms in the Indian population: a possible paternal 5'UTR-CGG-repeat-allele effect on autism

Autism is a neurodevelopmental disorder with high heritability factor and the reelin gene, which codes for an extracellular matrix protein involved with neuronal migration and lamination is being investigated as a positional and functional candidate gene for autism. It is located on chromosome 7q22 within the autism susceptible locus (AUTS1); identified in earlier genome scans and several investigations have been carried out on various ethnic groups to assess possible association and linkage of the gene with autism. However, the findings are still inconclusive. In the present study which represents the first report of such a study on the Indian population, genotyping analyses of CGG repeat polymorphism at 5'UTR, two single nucleotide polymorphisms (SNP) at exon 6 and exon 50 were performed in 73 autistic subjects, 129 parents, and 80 controls. The allelic distributions of the repeat polymorphism and exon 50 T/C SNP were quite different from earlier reports in other populations. Allelic and genotypic distribution of the markers did not show any differences between the cases and controls. While our preliminary data on family-based association studies on 58 trios showed no preferential transmission of any allele from the parents to the affected offspring, TDT and HHRR analyses revealed significant paternal transmission distortions for 10- and > or =11-repeat alleles of CGG repeat polymorphism. Thus, the present study suggests that 5'UTR of reelin gene may have a role in the susceptibility towards autism with the paternal transmission and non-transmission respectively of 10- and > or =11-repeat alleles, to the affected offspring.

Genetic mouse models of schizophrenia: from hypothesis-based to susceptibility gene-based models

Translation of human genetic mutations into genetic mouse models is an important strategy to study the pathogenesis of schizophrenia, identify potential drug targets, and test new drugs for new antipsychotic treatments. Although it is impossible to recapitulate the full spectrum of schizophrenia symptoms in animal models, hypothesis-driven genetic mouse models have been successful in reproducing several schizophrenia-like behaviors and uncovering the roles of specific genes in dopamine and glutamine neurotransmission systems in mediating schizophrenia-like behaviors. Recent discoveries of susceptibility genes for schizophrenia and recognition of cognitive dysfunction as a core feature of schizophrenia and a phenotype of susceptibility for schizophrenia offer opportunities to develop newer genetic mouse models based on susceptibility. This new generation of genetic mouse models could shed light on the etiology of schizophrenia and lead us to new hypotheses, novel diagnostic tools, and more effective therapy.

Absence of association of a polymorphic GGC repeat at the 5' untranslated region of the reelin gene with schizophrenia

Reelin is an extracellular matrix glycoprotein that plays an important role in guiding neuronal migration, lamination and connection during embryonic brain development. Several reports suggest that reduced reelin expression is associated with human mental illnesses such as schizophrenia, mood disorders and autism. Human reelin cDNA has been cloned and contains a polymorphic GGC repeat at the 5' untranslated region. In view of the possible regulation of reelin gene expression by this GGC polymorphism, we investigated the association of the polymorphic GGC repeat with schizophrenia in a Chinese Han population from Taiwan. We found no differences of allelic and genotypic distributions of the polymorphic GGC triplets between 162 schizophrenic patients and 176 controls in this study. Our findings do not support the involvement of the polymorphic GGC triplets of the reelin gene in the pathogenesis of schizophrenia in the population studied.

Population-based and family-based association study of 5'UTR polymorphism of the reelin gene and schizophrenia

Reelin is a glycoprotein involved in the migration and positioning of proliferating neurons and synaptic connectivity during neurodevelopment. It may also modulate neuronal plasticity throughout life. Therefore, the reelin gene is a candidate gene for schizophrenia. We examined the association of the CGG repeat polymorphism in the 5'-untranslated region of the reelin gene with schizophrenia in 266 unrelated French Caucasian patients, 156 of their parents, and 103 controls. We found no difference in the allele distribution between patients and controls although there was a significant higher prevalence of the genotype 8-8 in controls (CLUMP T3: chi(2) = 6.3, P = 0.035). There was no significant transmission disequilibrium in intrafamilial analysis. To refine our phenotypic characterization and in accordance with converging evidence suggesting that treatment resistance is associated with indices of abnormal neurodevelopment, we studied the association between reelin gene polymorphism and response to antipsychotics. Patients who responded to antipsychotics had a higher frequency of both the (CGG)(10) allele and (CGG)(10)-containing genotypes (P = 0.02; P = 0.006, respectively), with an odd ratio for genotypes of 4.2 (CI = [1.4;12.4]). Our results weakly support an association of reelin gene variants with schizophrenia as a whole, yet suggest that reelin could be associated with treatment-resistant schizophrenia.

Reelin glycoprotein: structure, biology and roles in health and disease

Reelin glycoprotein is a secretory serine protease with dual roles in mammalian brain: embryologically, it guides neurons and radial glial cells to their corrected positions in the developing brain; in adult brain, Reelin is involved in a signaling pathway which underlies neurotransmission, memory formation and synaptic plasticity. Disruption of Reelin signaling pathway by mutations and selective hypermethylation of the Reln gene promoter or following various pre- or postnatal insults may lead to cognitive deficits present in neuropsychiatric disorders like autism or schizophrenia.

The GABA-glutamate connection in schizophrenia: which is the proximate cause?

Schizophrenia is a chronic, disabling psychiatric disorder that genetic studies have shown to be highly heritable. Although the dopamine hypothesis has dominated the thinking about the cause of schizophrenia for 40 years, post-mortem and genetic studies have provided little support for it. Rather, post-mortem studies point to hypofunction of subsets of GABAergic interneurons in the prefrontal cortex and the hippocampus. Furthermore, clinical pharmacologic, post-mortem and genetic studies have provided compelling evidence of hypofunction of a subpopulation of NMDA receptors in schizophrenia. In support of this inference, agents that directly or indirectly activate the glycine modulatory site on the NMDA receptor (the Glycine B receptor) reduce symptoms in chronic schizophrenia, especially negative symptoms and cognitive impairments. Electrophysiologic and pharmacologic studies suggest that the vulnerable NMDA receptors in schizophrenia may be concentrated on cortico-limbic GABAergic interneurons, thereby linking these two neuropathologic features of the disorder.

Molecular abnormalities of the hippocampus in severe psychiatric illness: postmortem findings from the Stanley Neuropathology Consortium

Between 1997 and 2002, 48 data sets from the hippocampus were produced on samples from the Stanley Neuropathology Consortium. From these data sets, 224 total measures were available from the various subdivisions of the hippocampus. An integrative analysis of these measures was performed using a multivariate, nonparametric analysis of variance (ANOVA). ANOVA with correction for multiple comparisons indicated that parvalbumin-containing cells in CA2 were reduced in schizophrenia and bipolar disorder. In addition, reelin protein in the molecular layer of the dentate gyrus was decreased in schizophrenia, bipolar disorder, and depression at the trend level of statistical significance (P=0.065). These results strongly suggest a dysfunction of inhibitory GABA-ergic interneurons in severe mental illness. Without correction for multiple comparisons, 31 measures were abnormal in at least one disease, whereas 11 measures would be expected to appear abnormal by chance. Abnormal molecules included measures of synaptic density or neuronal plasticity (reelin, SNAP-25, BDNF, Complexin I and II), as well as parvalbumin, tyrosine receptor kinase A, glucocorticoid receptors, glutamate NR1 receptor subunits, serotonin 5HT2(A) and 5HT1(B) receptors, and dopamine D(5) receptors.

Behavioral phenotype of the reeler mutant mouse: effects of RELN gene dosage and social isolation

Reeler (rl/rl) and reeler/wild-type (+/rl) mice synthesize Reln at subnormal rates, as do patients with schizophrenia, bipolar disorder, and autism, thereby forming the basis for a Reln hypothesis for vulnerability to these psychopathologies and justifying attention to the behavioral phenotypes of Reln-deficient mice. Tests of gait, emotionality, social aggression, spatial working memory, novel-object detection, fear conditioning, and sensorimotor reflex modulation revealed the behavioral phenotype of rl/rl, but not +/rl, mice to be different from that of wild-type (+/+) mice. These results reveal no effect of Reln gene dosage and provide significant challenges to both the Reln and the neurodevelopmental hypotheses of the etiology of major psychopathologies.

Methodological factors influencing measurement and processing of plasma reelin in humans

BACKGROUND

Reelin, intensively studied as an extracellular protein that regulates brain development, is also expressed in a variety of tissues and a circulating pool of reelin exists in adult mammals. Here we describe the methodological and biological foundation for carrying out and interpreting clinical studies of plasma reelin.

RESULTS

Reelin in human plasma was sensitive to proteolysis, freeze-thawing and heating during long-term storage, sample preparation and electrophoresis. Reelin in plasma was a dimer under denaturing conditions. Boiling of samples resulted in laddering, suggesting that each of the 8 repeats expressed in reelin contains a heat-labile covalent bond susceptible to breakage. Urinary-type and tissue-type plasminogen activator converted reelin to a discrete 310 kDa fragment co-migrating with the major immunoreactive reelin fragment seen in plasma and also detected in brain. (In contrast, plasmin produced a spectrum of smaller unstable reelin fragments.) We examined archival plasma of 10 pairs of age-matched male individuals differing in repeat length of a CGG repeat polymorphism of the 5'-untranslated region of the reelin gene (both alleles < 11 repeats vs. one allele having >11 repeats). Reelin 310 kDa band content was lower in subjects having the long repeats in all 10 pairs, by 25% on average (p < 0.001). In contrast, no difference was noted for amyloid precursor protein.

CONCLUSIONS

Our studies indicate the need for caution in measuring reelin in archival blood samples, and suggest that assays of plasma reelin should take into account three dimensions that might vary independently: a) the total amount of reelin protein; b) the relative amounts of reelin vs. its proteolytic processing products; and c) the aggregation state of the native protein. Reelin-plasminogen activator interactions may affect their roles in synaptic plasticity. Our results also suggest that the human CGG repeat polymorphism affects reelin gene expression, and may affect susceptibility to human disease.