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Flashcards in Genetics of Schizophrenia Deck (26)
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When is the typical onset of schizophrenia?

Late adolescence or early adulthood


State the 3 main symptom domains of schizophrenia

Positive symptoms, negative symptoms, cognitive problems


State some positive symptoms of schizophrenia

Delusions, hallucinations, disorganised speech


State some negative symptoms of schizophrenia

Social withdrawal, apathy, emotional blunting


State some cognitive problems of schizophrenia

Difficulties with memory, attention, and processing speed


Give at least 5 risk factors implicated in schizophrenia

Genetics, paternal age, maternal famine, infection while pregnant, season of birth, hypoxia at birth, urban dwelling, adolescent cannabis use, migration


State the monozygotic twin concordance of schizophrenia



What is a linkage study?

A study looking at the co-inheritance of genetic markers on chromosomes in families with high incidence of a disease to try and identify markers linked to that disease


Why are dopamine receptor D2 genes or associated genes candidate genes in schizophrenia?

Most drugs for schizophrenia target dopamine receptor D2


What is the aim of genome wide association studies (GWAS)?

To identify single base variants (SNPs) associated with a clinical condition


Which main gene areas have been implicated in schizophrenia by genome wide association studies?

Genes involved in glutamate neurotransmission, synaptic plasticity, and voltage-gated calcium channel subunits


Where are most SNPs implicated in schizophrenia expressed?

The brain and immune tissues, particularly the MHC locus


Name 2 rare schizophrenia alleles

Disrupted in schizophrenia 1 (DISC1) and 22q11 deletion syndrome


Which mental disorders does disrupted in schizophrenia 1 (DISC1) predispose to?

Schizophrenia, bipolar disorder, recurrent major depression, adolescent conduct disorder, anxiety disorder, alcohol abuse


What is disrupted in schizophrenia 1 (DISC1)?

A translocation between chromosome 1 and chromosome 11


What does 22q11 deletion syndrome cause?

Velo-cardial facial syndrome, characterised by hypoparathyroidism, and underdeveloped or absent thymus (and consequent immune problems), heart defecrs, and a cleft lip or palate - as well as schizophrenia in 1/3 of patients


What type of study identifies deletion syndromes?

Copy number variant studies


Which disorders is 15q11 deletion associated with?

Autism spectrum disorder, Angelmann syndrome, Prader-Willi syndrome


What is next generation sequencing used to identify?

De novo mutations - those found in the child but not either parent


Describe the results of Fromer et al & Purcell et al's 2014 studies into de novo mutations in schizophrenia

De novo mutations were not more common in schizophrenics, but mutations were more commonly located in the ARC, MNDAr, and FMRP pathways (synaptic pathways)


What does transcriptomics look at?

All the genes present in and expressed by a tissue


State the brain regions implicated in schizophrenia

Frontal and temporal cortices


Name a candidate gene in schizophrenia identified from expression profiling studies

Zinc transporter ZnT3


Describe the relationship between zinc and brain function

Suboptimal zinc nutrition during gestation in rats causes long-term effects on brain function (Aimo et al, 2010), and zinc supplementation is beneficial in major depression (Nowak et al, 2011)


Describe the relationship between ZnT3 and schizophrenia

ZnT3 has been identified as a candidate gene in expression profiling, and there are four SNPs associated with ZnT3 and schizophrenia - all of which are consistent with a dominant model for disease penetrance


Where do the candidate differentially expressed genes implicated in schizophrenia appear to localise to? (Maycox et al, 2009)

The synaptome