biology

Rs6265

Rs6265 is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rs6265 rather than just read about it. In short: Rs6265, also called Val66Met or G196A, is a gene variation, a single nucleotide polymorphism (SNP) in the BDNF gene that codes for brain-derived neurotrophic factor. Well over a hundred research studies have examined the polymorphism.

Key takeaways

Rs6265 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Rs6265 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Rs6265 from memory before moving on to harder problems.

Reference excerpt

Rs6265, also called Val66Met or G196A, is a gene variation, a single nucleotide polymorphism (SNP) in the BDNF gene that codes for brain-derived neurotrophic factor. Well over a hundred research studies have examined the polymorphism.

Association with neuropsychiatric disorders Numerous studies have examined the role of this polymorphism in risk of neuropsychiatric disorders, including (but not limited to) schizophrenia and depression. It is generally thought that some variants of the polymorphism lead to memory impairment and susceptibility to neuropsychiatric disorders, and a 2007 meta-analysis of case-control studies found a relationship between the SNP and substance-related disorders, eating disorders, and schizophrenia. Another 2007 meta-analysis could, however, find no association between the SNP and schizophrenia or bipolar disorder. Meta-analyses of Alzheimer's disease and Parkinson's disease also indicate that the SNP has little or no association with these diseases. Also inconsistencies in association studies with depression have been noted. The reason for these inconsistent results have been suggested to stem from several sources, with one recent review arguing that statistical artefact, sampling bias, population stratification and uncontrolled gene-environment interactions are likely to underscore this effect. These same authors recently published a report which found that transgenic mice engineered to express human BDNF as well as carry the Val66Met permutation are selectively sensitive to the glucocorticoid stress hormone corticosterone (rodent equivalent of cortisol), which in turn primes the fear circuitry and hippocampus-dependent memory function of Met/Met homozygous mice. As hippocampal function is a core component of several psychiatric conditions, and stress is a non-specific but substantial risk factor for affective, anxiety, eating and psychotic disorders, Notaras et al. argue that "there is a long-term effect of glucocorticoids in 66Met carriers that potentiates the fear circuitry into adulthood, which may increase susceptibility to trauma, events with negative emotional valence and related psychopathology". This interpretation is consistent with a suggested role of BDNF and the Val66Met polymorphism in post-traumatic stress disorder, where it has been shown that 66Met variant perturbs extinction learning in both man and mouse. The Val66Met polymorphism alters vulnerability to stress in mice and humans, which likely contributes to PTSD risk. In treatment response studies val/val homozygotes may respond better than met allele carriers with drug resistant depression treated with repetitive transcranial magnetic stimulation.

Subject variables in healthy humans One study has reported that met/met carriers tend to have lower body mass index compared to the two other genotypes. Another study showed that subjects with the val/val genotype had higher mean intelligence. The same study found no association with personality traits as measured with the Tridimensional Personality Questionnaire. Also a Polish 2007 study observed no significant relationship between the polymorphism and personality in healthy females. A German 2005 study could though find an association with personality traits measured with NEO-Five Factor Inventory, with val/val subjects scoring higher on anxiety and neuroticism dimensions. Large studies and a meta-analysis inclusive of over 15,000 subjects, however, found no association between the Val66Met and Neuroticism.

Other studies A study in transgenic mice has found that met/met mice exhibits increased anxiety-related behaviors.

References

Worked examples

Example 1 — a first encounter with Rs6265

Start with the simplest possible case. Write down what Rs6265 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rs6265 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rs6265 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rs6265

In research: Rs6265 appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Rs6265 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Rs6265 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Biology of bipolar disorder, SNPs on chromosome 11, so understanding it makes those chapters shorter.
In everyday life: Look for Rs6265 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Rs6265 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Rs6265 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Rs6265 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rs6265 in simple terms?

Why does Rs6265 matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rs6265?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rs6265.