Annick Salzmann

Increased methylation of glucocorticoid receptor gene ( NR3C1 ) in adults with a history of childhood maltreatment: a link with the severity and type of trauma

Childhood maltreatment, through epigenetic modification of the glucocorticoid receptor gene (NR3C1), influences the hypothalamic–pituitary–adrenal axis (HPA axis). We investigated whether childhood maltreatment and its severity were associated with increased methylation of the exon 1F NR3C1 promoter, in 101 borderline personality disorder (BPD) and 99 major depressive disorder (MDD) subjects with, respectively, a high and low rate of childhood maltreatment, and 15 MDD subjects with comorbid post-traumatic stress disorder (PTSD). Childhood sexual abuse, its severity and the number of type of maltreatments positively correlated with NR3C1 methylation (P=6.16 × 10−8, 5.18 × 10−7 and 1.25 × 10−9, respectively). In BPD, repetition of abuses and sexual abuse with penetration correlated with a higher methylation percentage. Peripheral blood might therefore serve as a proxy for environmental effects on epigenetic processes. These findings suggest that early life events may permanently impact on the HPA axis though epigenetic modifications of the NR3C1. This is a mechanism by which childhood maltreatment may lead to adulthood psychopathology.

Response to psychotherapy in borderline personality disorder and methylation status of the BDNF gene

Downregulation of brain-derived neurotrophic factor (BDNF) gene expression with corresponding increased methylation at specific promoters has been associated with stressful experiences in early life and may explain later adulthood psychopathology. We measured the percentage of methylation at BDNF CpG exons I and IV as well as plasma BDNF protein levels in 115 subjects with borderline personality disorder (BPD) and 52 controls. BPD subjects then underwent a 4-week course of intensive dialectical behavior therapy (I-DBT). BDNF methylation status and protein levels were re-assessed at the end of treatment. BPD subjects had significantly higher methylation status in both CpG regions than controls. In addition, the higher the number of childhood trauma, the higher was the methylation status. In BPD subjects, BDNF methylation significantly increased after I-DBT. Nonresponders accounted for the majority of this increase, whereas responders showed a decrease in methylation status over time. Accordingly, the changes in methylation status over time were significantly associated with changes in depression scores, hopelessness scores and impulsivity. No association was found between protein levels and BDNF methylation status. We here found a relationship between child maltreatment and higher DNA methylation of BDNF. These results moreover support the idea that these epigenetic marks may be changed through psychotherapeutic approaches and that these changes underline changes in cognitive functions.

Rare Genotype Combination of the Serotonin Transporter Gene Associated With Treatment Response in Severe Personality Disorder

The insertion deletion (ins/del) polymorphism of the serotonin transporter gene (5‐HTTLPR) has been associated with several psychiatric phenotypes and antidepressants response. We investigated, in a large cohort of 5,608 controls and subjects suffering from various psychiatric disorders, the frequency of haplotypes and corresponding genotypes combining the 5‐HTTLPR and the other serotonin transporter promoter functional variant (rs25531). We showed that rs25531 lies 18 bp 5′ to the site where the 43 bp (and not 44 bp as previously described) ins/del defines the 14‐ and 16‐repeat alleles. These polymorphisms should therefore be considered as four alleles instead of a triallelic unique locus. The very rare G‐14/G‐16 genotype was carried on by only three subjects. These are women with a history of suicide attempt with a psychiatric history strongly suggesting a borderline personality disorder. Two of them have shown a non‐response to serotoninergic antidepressant. Interestingly, in one of them was observed a spectacular response after the introduction of bupropion. The genotyping droved our therapeutic approach, by preferring a dopaminergic over a serotoninergic agent. This study highlights the usefulness of studying very rare clinical cases as well as rare variants, in order to deal with the biological heterogeneity of spectral disorders.

Carboxypeptidase A6 gene (CPA6) mutations in a recessive familial form of febrile seizures and temporal lobe epilepsy and in sporadic temporal lobe epilepsy

Febrile seizures (FS) and temporal lobe epilepsy (TLE) were found in four of the seven siblings born to healthy Moroccan consanguineous parents. We hypothesized autosomal recessive (AR) inheritance. Combined linkage analysis and autozygosity mapping of a genome‐wide single nucleotide polymorphism genotyping identified a unique identical by descent (IBD) locus of 9.6 Mb on human chromosome 8q12.1‐q13.2. Sequencing of the 38 genes mapped within the linked interval revealed a homozygous missense mutation c.809C>T (p.Ala270Val) in the carboxypeptidase A6 gene (CPA6). Screening all exons of CPA6 in unrelated patients with partial epilepsy (n = 195) and FS (n = 145) revealed a new heterozygous missense mutation c.799G>A (p.Gly267Arg) in three TLE patients. Structural modeling of CPA6 indicated that both mutations are located near the enzymes active site. In contrast to wild‐type CPA6, which is secreted and binds to the extracellular matrix where it is enzymatically active, Ala270Val CPA6 was secreted at about 40% of the level of the wild‐type CPA6 and was fully active, while Gly267Arg CPA6 was not detected in the medium or extracellular matrix. This study suggests that CPA6 is genetically linked to an AR familial form of FS and TLE, and is associated with sporadic TLE cases. Hum Mutat 33:124–135, 2012.

Functional variant in complement C3 gene promoter and genetic susceptibility to temporal lobe epilepsy and febrile seizures.

Background Human mesial temporal lobe epilepsies (MTLE) represent the most frequent form of partial epilepsies and are frequently preceded by febrile seizures (FS) in infancy and early childhood. Genetic associations of several complement genes including its central component C3 with disorders of the central nervous system, and the existence of C3 dysregulation in the epilepsies and in the MTLE particularly, make it the C3 gene a good candidate for human MTLE. Methodology/Principal Findings A case-control association study of the C3 gene was performed in a first series of 122 patients with MTLE and 196 controls. Four haplotypes (HAP1 to 4) comprising GF100472, a newly discovered dinucleotide repeat polymorphism [(CA)8 to (CA)15] in the C3 promoter region showed significant association after Bonferroni correction, in the subgroup of MTLE patients having a personal history of FS (MTLE-FS+). Replication analysis in independent patients and controls confirmed that the rare HAP4 haplotype comprising the minimal length allele of GF100472 [(CA)8], protected against MTLE-FS+. A fifth haplotype (HAP5) with medium-size (CA)11 allele of GF100472 displayed four times higher frequency in controls than in the first cohort of MTLE-FS+ and showed a protective effect against FS through a high statistical significance in an independent population of 97 pure FS. Consistently, (CA)11 allele by its own protected against pure FS in a second group of 148 FS patients. Reporter gene assays showed that GF100472 significantly influenced C3 promoter activity (the higher the number of repeats, the lower the transcriptional activity). Taken together, the consistent genetic data and the functional analysis presented here indicate that a newly-identified and functional polymorphism in the promoter of the complement C3 gene might participate in the genetic susceptibility to human MTLE with a history of FS, and to pure FS. Conclusions/Significance The present study provides important data suggesting for the first time the involvement of the complement system in the genetic susceptibility to epileptic seizures and to epilepsy.

Candidate genes for temporal lobe epilepsy: a replication study

The objective of this study is to replicate previously published results regarding the involvement of several susceptibility genes in temporal lobe epilepsy (TLE): interleukin 1β (IL-1β), interleukin 1β (IL-1α), interleukin 1RA (IL-1RA), apolipoprotein E (ApoE) and prodynorphin (PDYN). We used a case-control approach comparing several polymorphisms within these candidate genes between unrelated TLE patients and matched controls. We were thus able to confirm the role of ApoE, IL-1α and IL-1RA genes in TLE disease, but failed to confirm the involvement of IL-1β and PDYN. This failure should be interpreted with caution, as this may be due to the small size of our study groups and the resultant lack of statistical power.

Increased CPA6 promoter methylation in focal epilepsy and in febrile seizures

Focal epilepsy (FE) is one of the most common forms of adult epilepsy and is usually regarded as a multifactorial disorder. Febrile seizures (FS) often appear during childhood in a subtype of FE patients, i.e. with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). FS are the most common human convulsive event associated with fever. Genetic evidences for FS have suggested a complex mode of inheritance. Until now, to investigate genes at the genomic level, linkage analysis of familial forms and association studies have been performed, but nothing conclusive has been clearly related to FE and FS. As complex disorders, environmental factors might play a crucial role through epigenetic modification of key candidate genes such as CPA6, which encodes Carboxypeptidase A6, an extracellular protein. Therefore, we assessed DNA methylation in promoter of CPA6. In 186 FE patients and 92 FS patients compared to 93 healthy controls and 42 treated controls with antiepileptic drugs (AEDs), we found significant higher levels of methylation for epileptic patients. Methylation status were 3.4% (±3.2%) for FE cases and 4.3% (±3.5%) for FS cases, whereas healthy individuals and treated controls with AEDs showed a level of 0.8% (±2.9%) and 1.5% (±3.9%), respectively (p≤0.001 for all comparisons). These results let growing evidence for DNA methylation involvment in FE and FS.

Genetic association of the Phosphoinositide‐3 kinase in schizophrenia and bipolar disorder and interaction with a BDNF gene polymorphism

Phosphoinositide‐3‐kinase, class III (PIK3C3) is a member of the phosphoinosite‐3‐kinases family, involved in cell signaling, membrane trafficking, and neurodevelopment. Previous studies have indeed shown an association between PIK3C3 gene variants and both bipolar disorder (BD) and schizophrenia (SZ). Brain‐derived neurotrophic factor (BDNF) is a neurodevelopmental factor, which can regulate the PI3K signaling pathway. Associations have been reported between BDNF gene polymorphisms and affective and psychotic disorders. The aim of the present study was to replicate an association between PIK3C3 and BDNF gene variants in SZ and BD and a putative epistasis between the two genes. Patients meeting the DSM‐IV criteria of BD and SZ were included in this study (98 BD and 79 SZ) as well as 158 healthy controls. Blood DNA was extracted and genotyping was performed either by the polymerase chain reaction (PCR) technique followed by enzymatic digestion or by the high‐resolution melt (HRM) method. Genotype and haplotype association was assessed with the UNPHASED statistical program.The results showed one nominal association with BD (P < 0.02) and two risk haplotypes in both SZ (P < 0.001) and BP (P < 0.0005), which survived multiple testing correction. A modest interaction between a BDNF variant and PI3KC3 polymorphism was observed (P < 0.04).These preliminary results confirm the genetic association of PI3K gene variants with both SZ and BD, and support the hypothesis that SZ and BD share a genetic background.

GABAB Receptor 1 Polymorphism (G1465A) and Temporal Lobe Epilepsy

Summary:  Purpose: To reevaluate the genetic contribution of the polymorphism G1465A of the gene coding for γ‐aminobutyric acid (GABA)B receptor 1 subunit [GABAB(1)] in a sample of French patients with temporal lobe epilepsy (TLE) and to perform an exploratory analysis in other phenotypic subgroups.

Replication of association between a SCN1A splice variant and febrile seizures.

In the present study, we assessed a SCN1A single nucleotide polymorphism (SNP) (rs3812718, IVS5N+5 G>A), first analyzed by Schlachter et al. We genotyped 164 patients with febrile seizures (FS) [of those 62 adults with focal epilepsy (FEFS+) and 102 children with pure FS (Pure FS)] and 199 matched controls. Moreover, we also tested a third subgroup of 113 patients with focal epilepsy syndromes without a history of FS (FEFS−); they all were Caucasian. Our results, as in the initial study of Schlachter et al., showed an increase in the A‐allele and AA‐genotype frequencies in patients with FS compared to the controls, but these current differences did not reach statistical significance. Subsequently, we pooled our data with previously published Caucasian groups. No statistically significant difference was found for the FEFS−, but analyses for FEFS+ and Pure FS are significantly different compared to controls (p = 8.08 e−6 and p = 3.56 e−4, respectively). Furthermore, pooled patients with FS (FS + FEFS+) tested against those without FS (Controls + FEFS−) showed an even greater statistical significance (p = 4.82 e−8). These results reinforced rs3812718 involvement in FS vulnerability.