The Brain Resource International Database and Brain Resource, Sydney, NSW, Australia and San Francisco, CA, USA Individual risk markers for depression and anxiety disorders have been identified but the explicit pathways that link genes and environment to these markers remain unknown. Here we examined the explicit interactions between the brain-derived neurotrophic factor (BDNF) Val66Met gene and early life stress (ELS) exposure in brain (amygdala-hippocampalprefrontal gray matter volume), body (heart rate), temperament and cognition in 374 healthy European volunteers assessed for depression and anxiety symptoms. Brain imaging data were based on a subset of 89 participants. Multiple regression analysis revealed main effects of ELS for body arousal (resting heart rate, P = 0.005) and symptoms (depression and anxiety, P < 0.001) in the absence of main effects for BDNF. In addition, significant BDNF-ELS interactions indicated that BDNF Met carriers exposed to greater ELS have smaller hippocampal and amygdala volumes (P = 0.013), heart rate elevations (P = 0.0002) and a decline in working memory (P = 0.022). Structural equation path modeling was used to determine if this interaction predicts anxiety and depression by mediating effects on the brain, body and cognitive measures. The combination of Met carrier status and exposure to ELS predicted reduced gray matter in hippocampus (P < 0.001), and associated lateral prefrontal cortex (P < 0.001) and, in turn, higher depression (P = 0.005). Higher depression was associated with poorer working memory (P = 0.005), and slowed response speed. The BDNF Met-ELS interaction also predicted elevated neuroticism and higher depression and anxiety by elevations in body arousal (P < 0.001). In contrast, the combination of BDNF V/V genotype and ELS predicted increases in gray matter of the amygdala (P = 0.003) and associated medial prefrontal cortex (P < 0.001), which in turn predicted startle-elicited heart rate variability (P = 0.026) and higher anxiety (P = 0.026). Higher anxiety was linked to verbal memory, and to impulsivity. These effects were specific to the BDNF gene and were not evident for the related 5HTT-LPR polymorphism. Overall, these findings are consistent with the correlation of depression and anxiety, yet suggest that partially differentiated gene-brain cognition pathways to these syndromes can be identified, even in a nonclinical sample. Such findings may aid establishing an evidence base for more tailored intervention strategies.
McLeod syndrome is caused by mutations of XK, an X-chromosomal gene of unknown function. Originally defined as a peculiar Kell blood group variant, the disease affects multiple organs, including the nervous system, but is certainly underdiagnosed. We analyzed the mutations and clinical findings of 22 affected men, aged 27 to 72 years. Fifteen different XK mutations were found, nine of which were novel, including the one of the eponymous case McLeod. Their common result is predicted absence or truncation of the XK protein. All patients showed elevated levels of muscle creatine phosphokinase, but clinical myopathy was less common. A peripheral neuropathy with areflexia was found in all but 2 patients. The central nervous system was affected in 15 patients, as obvious from the occurrence of seizures, cognitive impairment, psychopathology, and choreatic movements. Neuroimaging emphasized the particular involvement of the basal ganglia, which was also detected in 1 asymptomatic young patient. Most features develop with age, mainly after the fourth decade. The resemblance of McLeod syndrome with Huntington's disease and with autosomal recessive chorea-acanthocytosis suggests that the corresponding proteins--XK, huntingtin, and chorein--might belong to a common pathway, the dysfunction of which causes degeneration of the basal ganglia.
Summary Background Frontotemporal dementia (FTD) is a complex disorder characterised by a broad range of clinical manifestations, differential pathological signatures, and genetic variability. Mutations in three genes—MAPT, GRN, and C9orf72—have been associated with FTD. We sought to identify novel genetic risk loci associated with the disorder. Methods We did a two-stage genome-wide association study on clinical FTD, analysing samples from 3526 patients with FTD and 9402 healthy controls. All participants had European ancestry. In the discovery phase (samples from 2154 patients with FTD and 4308 controls), we did separate association analyses for each FTD subtype (behavioural variant FTD, semantic dementia, progressive non-fluent aphasia, and FTD overlapping with motor neuron disease [FTD-MND]), followed by a meta-analysis of the entire dataset. We carried forward replication of the novel suggestive loci in an independent sample series (samples from 1372 patients and 5094 controls) and then did joint phase and brain expression and methylation quantitative trait loci analyses for the associated (p<5 × 10−8) and suggestive single-nucleotide polymorphisms. Findings We identified novel associations exceeding the genome-wide significance threshold (p<5 × 10−8) that encompassed the HLA locus at 6p21.3 in the entire cohort. We also identified a potential novel locus at 11q14, encompassing RAB38/CTSC, for the behavioural FTD subtype. Analysis of expression and methylation quantitative trait loci data suggested that these loci might affect expression and methylation incis. Interpretation Our findings suggest that immune system processes (link to 6p21.3) and possibly lysosomal and autophagy pathways (link to 11q14) are potentially involved in FTD. Our findings need to be replicated to better define the association of the newly identified loci with disease and possibly to shed light on the pathomechanisms contributing to FTD. Funding The National Institute of Neurological Disorders and Stroke and National Institute on Aging, the Wellcome/ MRC Centre on Parkinson’s disease, Alzheimer’s Research UK, and Texas Tech University Health Sciences Center.
Hailey-Hailey disease (HHD) is an autosomal dominant skin disorder characterized by suprabasal cell separation (acantholysis) of the epidermis. Previous genetic linkage studies localized the gene to a 5 cM interval on human chromosome 3q21. After reducing the disease critical region to <1 cM, we used a positional cloning strategy to identify the gene ATP2C1, which is mutated in HHD. ATP2C1 encodes a new class of P-type Ca(2+)-transport ATPase, which is the homologue for the rat SPLA and the yeast PMR1 medial Golgi Ca(2+)pumps and is related to the sarco(endo)plasmic calcium ATPase (SERCA) and plasma membrane calcium ATPase (PCMA) families of Ca(2+)pumps. The predicted protein has the same apparent transmembrane organization and contains all of the conserved domains present in other P-type ATPases. ATP2C1 produces two alternative splice variants of approximately 4.5 kb encoding predicted proteins of 903 and 923 amino acids. We identified 13 different mutations, including nonsense, frameshift insertion and deletions, splice-site mutations, and non-conservative missense mutations. This study demonstrates that defects in ATP2C1 cause HHD and together with the recent identification of ATP2A2 as the defective gene in Darier's disease, provide further evidence of the critical role of Ca(2+)signaling in maintaining epidermal integrity.
Chorea-acanthocytosis (CHAC, MIM 200150) is an autosomal recessive neurodegenerative disorder characterized by the gradual onset of hyperkinetic movements and abnormal erythrocyte morphology (acanthocytosis). Neurological findings closely resemble those observed in Huntington disease. We identified a gene in the CHAC critical region and found 16 different mutations in individuals with chorea-acanthocytosis. CHAC encodes an evolutionarily conserved protein that is probably involved in protein sorting.
SIGMAR1 is a causative gene for familial FTLD-MND with a unique neuropathology that differs from other FTLD and MND cases. Our findings also suggest Sigma-1 drugs as potential treatments for the TDP-43/FUS proteinopathies.
We performed a prospective genotype-phenotype study using molecular screening and clinical assessment to compare the severity of disease and the risk of sarcoma in 172 individuals (78 families) with hereditary multiple exostoses. We calculated the severity of disease including stature, number of exostoses, number of surgical procedures that were necessary, deformity and functional parameters and used molecular techniques to identify the genetic mutations in affected individuals. Each arm of the genotype-phenotype study was blind to the outcome of the other. Mutations EXT1 and EXT2 were almost equally common, and were identified in 83% of individuals. Non-parametric statistical tests were used. There was a wide variation in the severity of disease. Children under ten years of age had fewer exostoses, consistent with the known age-related penetrance of this condition. The severity of the disease did not differ significantly with gender and was very variable within any given family. The sites of mutation affected the severity of disease with patients with EXT1 mutations having a significantly worse condition than those with EXT2 mutations in three of five parameters of severity (stature, deformity and functional parameters). A single sarcoma developed in an EXT2 mutation carrier, compared with seven in EXT1 mutation carriers. There was no evidence that sarcomas arose more commonly in families in whom the disease was more severe. The sarcoma risk in EXT1 carriers is similar to the risk of breast cancer in an older population subjected to breast-screening, suggesting that a role for regular screening in patients with hereditary multiple exostoses is justifiable.
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