A novel, putative gain-of-function haplotype at SLC6A4 associates with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a disabling neuropsychiatric illness with strong segregation data indicative of major genetic contributions. Association analyses of common functional variants of the serotonin transporter gene (SLC6A4), a long-standing OCD candidate, have so far been inconsistent. Here, we set out to investigate the role of additional functional SLC6A4 loci in OCD. We describe a common, functional C > T single nucleotide polymorphism, rs25532, located less than 150 nucleotides centromeric of the serotonin transporter-linked polymorphic region indel known as 5-HTTLPR. The minor allele of rs25532 significantly decreased luciferase reporter gene expression levels by 15-80%, depending on 5-HTTLPR allele background and cell type. Haplotype-based testing of rs25532 and all other known non-coding functional SLC6A4 variants revealed a highly significant omnibus association with OCD in a large case-control sample. Remarkably, the haplotype significantly overrepresented in probands contained the higher-expressing allele at each locus, supporting the notion of increased serotonin transporter functioning being pathogenetically involved in OCD. Conditional haplotype analyses with the software WHAP revealed that this association is primarily driven by 5-HTTLPR, rs25532 and rs16965628. Our results contribute to a better understanding of SLC6A4 expression genetics and provide a functional haplotype framework for future serotonin-related studies.     

Severe neurodevelopmental disorder with intractable seizures due to a novel SLC1A4 homozygous variant

IntroductionBiallelic variants in the SLC1A4 gene have been so far identified as a very rare cause of neurodevelopmental disorders with or without epilepsy and almost exclusively described in the Ashkenazi-Jewish population.Patients and methodsHere we present Czech patient with microcephaly, severe global developmental delay and intractable seizures whose condition remained undiagnosed despite access to clinical experience and standard diagnostic methods including examination with an epilepsy targeted NGS gene panel.ResultsWhole exome sequencing revealed a novel variant NM_003038.4:c.1370G > A p.(Arg457Gln) of the SLC1A4 gene in a homozygous state in the patient, and afterwards Sanger sequencing in both parents confirmed the biallelic origin of the variant. A variant in the same codon, but with a different amino acid exchange, was described previously in a patient that had a very similar phenotype, however, without epilepsy.ConclusionOur data suggest that the SLC1A4 gene should be considered in the diagnosis of patients with severe, early onset neurodevelopmental impairment with epilepsy and encourage the analysis of SLC1A4 gene variants via targeted NGS gene panel or whole exome sequencing.     

Acute onset of obsessive-compulsive disorder in males following childbirth.

Research on postpartum onset obsessive-compulsive disorder (OCD) has focused exclusively on females. However, the authors present four cases of males with OCD onset that coincide with a spouse's pregnancy or delivery. The rapid onset and content of obsessions and compulsions are remarkably similar to those reported in previous studies of postpartum OCD in females. Each patient also responded to cognitive-behavioral therapy using exposure procedures. The implications of these cases for etiological models of postpartum OCD and future research directions are discussed.     

Association of rare variation in the glutamate receptor gene SLC1A2 with susceptibility to bipolar disorder and schizophrenia

The SLC1A2 gene encodes the excitatory amino acid transporter 2 (EAAT2). Glutamate is the major mediator of excitatory neurotransmission and EAAT2 is responsible for clearing the neurotransmitter from the synaptic cleft. Genetic variation in SLC1A2 has been implicated in a range of neurological and neuropsychiatric conditions including schizophrenia (SZ), autism and in core phenotypes of bipolar disorder (BD). The coding and putative regulatory regions of SLC1A2 gene were screened for variants using high resolution melting or sequenced in 1099 or in 32 BD subjects. Thirty-two variants were detected in the SLC1A2 gene. Fifteen potentially etiological variants were selected for genotyping in 1099 BD and 1095 control samples. Five amino acid changing variants were also genotyped in 630 participants suffering from SZ. None of the variants were found to be associated with BD or SZ or with the two diseases combined. However, two recurrent missense variants (rs145827578:G>A, p.(G6S); rs199599866:G>A, p.(R31Q)) and one recurrent 5′-untranslated region (UTR) variant (ss825678885:G>T) were detected in cases only. Combined analysis of the recurrent-case-only missense variants and of the case-only missense and 5′-UTR variants showed nominal evidence for association with the combined diseases (Fisher''s P=0.019 and 0.0076). These findings are exploratory in nature and await replication in larger cohorts, however, they provide intriguing evidence that potentially functional rare variants in the SLC1A2 gene may confer susceptibility to psychotic disorders.     

Neuroimaging studies of obsessive-compulsive disorder in adults and children

Obsessive-compulsive disorder (OCD) is a severe, highly prevalent and chronically disabling disorder that usually emerges during childhood or adolescence. Neuroimaging studies play an important role in advancing our understanding of the pathophysiology of OCD and in developing neurocircuitry models of this psychiatric illness. This paper provided an updated, comprehensive review and analysis of the relevant literature on baseline functional and structural neuroimaging studies of OCD in both paediatric and adult patients. The neuroanatomical findings were presented in the context of two models: executive dysfunction, which implicates the dorsolateral prefrontal cortex, caudate nucleus, thalamus, and striatum; and modulatory control, which implicates the orbitofrontal and medial prefrontal cortex and the cingulate gyrus. Neuroanatomical findings were not consistent across all studies, and limitations were examined. Recommendations for future research directions and the implications of the results for improved treatment were explored.     

Association between the COMT locus and obsessive-compulsive disorder in females but not males

A polymorphism in the coding region of catechol-O-methyltransferase gene (COMT) was previously reported to be associated with obsessive-compulsive disorder (OCD), particularly in male probands. We attempted to replicate the previous finding using a family-based genetic design in haplotype relative risk (HRR) and transmission disequilibrium (TDT) analyses. Fifty-six OCD probands and their parents were genotyped for the COMT locus using established methods. Analysis of allele and genotype frequencies between the proband genotypes and the control (parental nontransmitted) genotypes failed to replicate the previous finding of gender divergence, gave no evidence of overall association, nor was linkage detected by TDT. However, further analysis of the COMT allele frequencies by proband gender gave evidence of a mildly significant association with the low-activity COMT allele in female probands (P=0.049), but not in male probands. These findings indicate that COMT may be etiologically relevant to OCD in a gender-specific manner opposite to that shown in previous studies.     

A novel SLC5A6 homozygous variant in a family with multivitamin-dependent neurometabolic disorder: Phenotype expansion and long-term follow-up

The sodium-dependent multivitamin transporter (hSMVT) encoded by the SLC5A6 gene is required for the intestinal absorption of biotin, pantothenic acid and lipoate, three micronutrients essential for normal growth and development. Systemic deficiency of these elements, either occurring from nutritional causes or genetic defects, is associated with neurological disorders, growth delay, skin and hair changes, metabolic and immunological abnormalities. A few patients with biallelic variants of SLC5A6 have been reported, exhibiting a spectrum of neurological and systemic clinical features with variable severity. We describe three patients from a single family carrying a homozygous p.(Leu566Valfs*33) variant of SLC5A6 disrupting the frame of the C-terminal portion of the hSMVT. In these patients, we documented a severe disorder featuring developmental delay, sensory polyneuropathy, optic atrophy, recurrent infections, and repeated episodes of intestinal pseudo-obstruction. Two patients who did not receive multivitamin supplementation therapy died in early infancy. In a third patient, early supplementation of biotin and pantothenic acid stabilized the clinical picture changing the course of the disease. These findings extend genotype-phenotype correlations and show how a timely and lifelong multivitamin treatment may be crucial to reduce the risk of life-threatening events in patients with pathogenic variants of the SLC5A6 gene.     

The genetic studies of obsessive-compulsive disorder and its future directions

Obsessive-compulsive disorder (OCD) is characterized by recurrent and persistent thoughts (obsessions), and repetitive behaviors or mental acts (compulsions). In Korea, an epidemiological study reported that the lifetime prevalence of OCD in the population was greater than two percent. The exact cause of OCD is still unknown. Evidence from familial, twin and segregation studies supports the role of a genetic component in the etiology of OCD. In addition, there is growing evidence that OCD has a specific neurochemical and neuroanatomical basis. According to this evidence, researchers have selected various candidate genes which have been implicated in the neurophysiology of OCD, and differences of allelic variants in OCD patients and controls have been analyzed. In this review we will introduce the results of previous genetic studies of OCD which have been performed in other populations, including twin studies, family studies, segregation analyses, linkage analyses, and association studies. In addition to these studies, we will present the results of our genetic studies of OCD performed in Korea.     

Complex segregation analysis of obsessive-compulsive disorder in 141 families of eating disorder probands, with and without obsessive-compulsive disorder

Probands affected with eating disorders (ED) present a higher number of relatives affected with obsessive-compulsive disorders/tic disorders than a comparison population. Therefore, we hypothesized that ED and obsessive-compulsive disorder (OCD) might share the same biological liability, and that a single major gene might account for that liability. We tested this hypothesis by applying a complex segregation analysis to 141 families of probands affected with ED (89 with anorexia nervosa, restricting and binge-eating types, 52 with bulimia nervosa). Given the hypothesized relationship between OCD and genetic spectrum disorders, we considered these diagnoses as affected phenotype in relatives. In Italian ED families, ED and OCD followed a Mendelian dominant model of transmission. When probands were divided according to co-diagnosis of OCD, best fit in the subgroup of families of 114 probands without OCD co-diagnosis was for a Mendelian dominant model of transmission whereas a Mendelian additive model of transmission represented best fit in the subgroup of families of 27 probands with an OCD co-diagnosis. Genetic transmission was not shown in those families where the only affected phenotype was ED. The existence of a Mendelian mode of genetic transmission within ED families supports the hypothesis that a common genetic liability could account for both ED and OCD.     

A non-synonymous variant in SLC30A8 is not associated with type 1 diabetes in the Danish population

Genome-wide association scans in type 2 diabetes (T2D) have identified a risk variant, rs13266634 (Arg325Trp), in SLC30A8 on chromosome 8. SLC30A8 encodes a β-cell specific zinc-ion transporter and rs13266634 has been shown to affect insulin secretion. Recently, autoantibodies for Slc30A8 with high predictive value were demonstrated in individuals with type 1 diabetes (T1D), making this gene an interesting T1D candidate gene. We genotyped rs13266634 in 3008 cases and controls and 246 families from Denmark. Association to T1D could not be demonstrated.     

A family study of obsessive-compulsive disorder with pediatric probands.

Obsessive-compulsive disorder (OCD) is a heterogeneous disorder of unknown etiology. We examined the lifetime history of obsessions, compulsions, and OCD in the first- and second-degree relatives of 35 pediatric probands with OCD and 17 controls with no psychiatric diagnosis. All available first-degree relatives were directly interviewed blind to proband status with two semi-structured interviews. Parents were also interviewed to systematically assess the family psychiatric history of first- and second-degree relatives. Best-estimate lifetime diagnoses were made using all available sources of information. Data were analyzed with logistic regression by the generalized estimating equation method and with robust Cox regression models. The lifetime prevalence of definite OCD was significantly higher in case than control first-degree relatives (22.5% vs. 2.6%, P < 0.05). Compared to controls, case first-degree relatives also had significantly higher lifetime rates of obsessions and compulsions (both P < 0.05). There was no significant difference between case and control second-degree relatives in lifetime rates of OCD. First-degree relatives of case probands with ordering compulsions had a significantly higher lifetime rate of definite and subthreshold OCD than relatives of case probands without ordering compulsions (45.4% vs. 18.8%, P < 0.05). The lifetime prevalence of definite OCD was significantly higher in case first-degree relatives with a history of tics than in case first-degree relatives without a tic history (57.1% vs. 20.9%, P < 0.01). The results provide further evidence that early-onset OCD is highly familial and suggest that two clinical variables are associated with its familial aggregation.     

Functional and structural analysis of rare SLC2A2 variants associated with Fanconi‐Bickel syndrome and metabolic traits

Deleterious variants in SLC2A2 cause Fanconi‐Bickel Syndrome (FBS), a glycogen storage disorder, whereas less common variants in SLC2A2 associate with numerous metabolic diseases. Phenotypic heterogeneity in FBS has been observed, but its causes remain unknown. Our goal was to functionally characterize rare SLC2A2 variants found in FBS and metabolic disease‐associated variants to understand the impact of these variants on GLUT2 activity and expression and establish genotype‐phenotype correlations. Complementary RNA‐injected Xenopus laevis oocytes were used to study mutant transporter activity and membrane expression. GLUT2 homology models were constructed for mutation analysis using GLUT1, GLUT3, and XylE as templates. Seventeen FBS variants were characterized. Only c.457_462delCTTATA (p.Leu153_Ile154del) exhibited residual glucose uptake. Functional characterization revealed that only half of the variants were expressed on the plasma membrane. Most less common variants (except c.593 C>A (p.Thr198Lys) and c.1087 G>T (p.Ala363Ser)) exhibited similar GLUT2 transport activity as the wild type. Structural analysis of GLUT2 revealed that variants affect substrate‐binding, steric hindrance, or overall transporter structure. The mutant transporter that is associated with a milder FBS phenotype, p.Leu153_Ile154del, retained transport activity. These results improve our overall understanding of the underlying causes of FBS and impact of GLUT2 function on various clinical phenotypes ranging from rare to common disease.     

Interaction between genetic variants of DLGAP3 and SLC1A1 affecting the risk of atypical antipsychotics-induced obsessive-compulsive symptoms

Adverse effects of atypical antipsychotics (AAP) can include obsessive-compulsive (OC) symptoms. Based on biological evidence of the relationship between the glutamatergic system and both OC disorder and AAP, this study aimed to determine whether DLGAP3, coding a post-synaptic scaffolding protein of glutamatergic synapses, is associated with AAP-induced OC symptoms. Furthermore, we explored the interactions between DLGAP3 and a previously reported susceptibility gene, the glutamate transporter gene SLC1A1, regarding this phenotype. Subjects were clinically stable schizophrenia patients receiving AAP treatment (n = 94), and they comprised an OC group (n = 40) and a non-OC group (n = 54) (patients with and without AAP-induced OC symptoms, respectively). We performed allelic/genotypic/haplotype association analyses for seven tag single-nucleotide polymorphisms of DLGAP3 and gene-gene interaction analyses with rs2228622 of SLC1A1, observing a nominally significant association between AAP-induced OC symptoms and rs7525948 in both simple chi-square tests and the regression analyses (nominal P < 0.05). In the logistic regression analysis of gene-gene interaction, we found a significant interaction effect of rs7525948 of DLGAP3 and rs2228622 of SLC1A1 (permutation P = 0.036) on AAP-induced OC symptoms, with a 30.2 times higher odds for individuals carrying risk genotypes at both loci in comparison with the reference group, which had no risk genotypes. This study provides suggestive evidence that DLGAP3 and its interactive effect with SLC1A1 might be involved in susceptibility to developing OC symptoms in schizophrenia patients receiving AAP treatment.     

强迫性障碍完美主义心理及防御方式的病例对照研究

目的:探讨强迫性障碍患者的完美主义心理特点及其与心理防御机制之间的关系。方法:在本病例对照研究中,选取71名符合ICD-10精神与行为障碍分类中强迫性障碍诊断标准的门诊或住院患者(病例组),及71名按照性别、年龄(±5岁)、受教育程度进行配比的无精神障碍的志愿者(对照组),用中文Frost多维度完美主义问卷(Chinese Frost Multidimensional Perfectionism Scale,CFMPS)、防御方式问卷(Defense Styles Questionnaire,DSQ)进行调查。结果:病例组的CFMPS总分[(88.5±16.2)vs.(63.0±10.7)]和担心错误[(16.4±6.4)vs.(11.6±4.0)]、行动的疑虑[(14.6±3.6)vs.(8.8±2.7)]、条理性[(23.4±5.3)vs.(17.2±4.1)]、个人标准[(19.6±5.1)vs.(14.8±3.7)]、父母期望[(14.5±5.0)vs.(10.7±3.5)]维度分,及DSQ的不成熟防御机制[(4.8±0.6)vs.(3.7±0.6)]、中间型防御机制[(4.9±0.5)vs.(4.2±0.6)]因子分均高于对照组,而DSQ的成熟防御机制因子分低于对照组[(3.8±0.6)vs.(5.7±0.8),P0.05]。完美主义总分与不成熟防御机制、中间型防御机制正相关(r=0.58,0.44,P0.01),与成熟防御机制负相关(r=-0.58,P0.01)。Logistic回归分析显示行动的疑虑是强迫性障碍的危险因素(OR=1.46;95%CI=1.09~1.94)。结论:强迫性障碍患者可能比正常人更追求完美,更多使用不成熟和中间型防御机制。     

Adenosine A1 receptor and bipolar affective disorder: systematic screening of the gene and association studies

In the present study we sought to identify genetic variation in the adenosine A₁ receptor (A₁AR) gene on chromosome 1q31-32.1, which through alteration of protein function or level of expression might contribute to the genetic predisposition to bipolar affective disorder. We performed a systematic mutation scan of the whole coding sequence as well as 5′ and 3′ untranslated regions by means of single-strand conformation analysis. The region upstream to the coding sequence we investigated contains two functional promoters. Screening 42 patients with bipolar affective disorder, we detected 11 DNA sequence variants (48T/A, 267 + 275C/T, 805T/G, 1777C/A, 1827C/T, 1904C/T, 2126G/T, 2294insT, 2776C/T, 2777del36, 2819T/G). Determining the frequency of these variants in 42 anonymous blood donors, we observed a non-significant (P < 0.06) trend towards an underrepresentation of the 2126T variant in patients when compared to controls. On the other hand, the 2777del36 and the 2819G variant were not found among the controls. These findings were followed up in a large independent replication sample. However, we were not able to confirm the initial findings in the second sample. Our data suggest that genetically determined variation of the A₁AR and its two promoters do not play a major role in the development of bipolar affective disorder. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 81:18–23, 1998. © 1998 Wiley-Liss, Inc.     

A rare variant in CYP27A1 and its association with atopic dermatitis with high serum total IgE

This study investigated rare variants associated with atopic dermatitis. We performed exome analyses on 37 patients who were diagnosed with atopic dermatitis by board‐certified dermatologists and had total serum IgE levels greater than 1000 IU/ml. The exome analysis identified seven variants with <1% allele frequency in Asian (ASN) population of 1000 Genomes Project phase 1 data and >5% allele frequency in the atopic dermatitis exome samples. We then conducted a replication study using 469 atopic dermatitis patients with total serum IgE ≥1000 IU/ml and 935 Japanese controls to assess the presence of these 7 candidate variants. The replication study confirmed that CYP27A1 rs199691576 (A/G) was associated with atopic dermatitis with high serum IgE levels (P = 0.012, odds ratio = 2.1). CYP27A1 is involved in the metabolism of vitamin D3, which plays important roles in modulating immune function. Previous studies have reported polymorphisms in vitamin D pathway genes that are associated with allergy‐related phenotypes. Our data confirm the importance of genes regulating the vitamin D pathway in the development of atopic dermatitis.