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Mutation, Gene Flow, and Genetic Drift

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).

Genetic Variation

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Genetic variation is the diversity in DNA sequences found among individuals of the same species. This diversity is crucial for a species' survival because it helps organisms adapt to environmental changes. Genetic variation begins with fertilization, where an egg and sperm cell merge. Each of these cells carries 23 chromosomes, up to 46 in the fertilized egg. Chromosomes are long DNA strands that contain genes, the basic units of heredity.
Genes exist in different versions called alleles,...

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Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.

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A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia

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Genetic Variation and Stroke Recovery: The STRONG Study.

Steven C Cramer^1,2, Livia Parodi³, Zahra Moslemi⁴

¹Department of Neurology, UCLA, Los Angeles, CA (S.C.C.).

|July 9, 2024

Summary

This summary is machine-generated.

Genetic variants influence stroke recovery, impacting cognition, depression, and PTSD. Post-stroke stress levels modify genetic susceptibility to these outcomes, highlighting the interplay between genes and environment in recovery.

Keywords:

depression genetic polymorphism genetics hand strength paresis posttraumatic stress disorder stroke

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Area of Science:

Neuroscience
Genetics
Psychiatry

Background:

Genetic association studies are crucial for understanding stroke recovery mechanisms and identifying therapeutic targets.
The STRONG study investigated genetic associations with motor, functional, and stress-related outcomes in stroke survivors.
Limited research has focused on the genetic underpinnings of stroke recovery and its associated psychological sequelae.

Purpose of the Study:

To examine the association between candidate genetic variants and motor/functional outcomes post-stroke.
To investigate the relationship between genetic variants and stress-related outcomes, including depression and PTSD, after stroke.
To explore how post-stroke stress levels modulate genetic susceptibility to psychological outcomes.

Main Methods:

Prospective, longitudinal genetic study (STRONG) involving 763 adult stroke survivors across 28 US centers.
Analysis of candidate gene variants (e.g., BDNF, ACE, COMT) for associations with cognitive, functional, mood, depression, and PTSD outcomes.
Statistical modeling using regression analyses, controlling for covariates, with Holm-Bonferroni correction for multiple comparisons.

Main Results:

The BDNF gene variant (rs6265) was associated with poorer cognitive function one year post-stroke.
Specific genetic variants (ACE, FAAH, COMT) influenced the relationship between post-stroke stress and the development of depression and PTSD symptoms.
The study successfully replicated findings from the GISCOME study regarding a specific polymorphism and functional recovery.

Conclusions:

Genetic factors play a significant role in cognitive function, depression, and PTSD development following stroke.
The impact of genetic susceptibility on PTSD and depressive symptoms is moderated by the level of post-stroke stress.
Genetic association studies offer valuable insights into the biological mechanisms underlying human stroke recovery.