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Concept
The FMR1 gene is crucial for normal cognitive development and is associated with Fragile X syndrome, a leading cause of inherited intellectual disability. Mutations in this gene, particularly CGG trinucleotide repeat expansions, lead to the silencing of the gene and subsequent loss of the fragile X mental retardation protein (FMRP), which is essential for synaptic function and plasticity.
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X-linked inheritance refers to the transmission of genes located on the X chromosome, which can result in different patterns of inheritance and expression in males and females due to the presence of one X chromosome in males and two in females. This type of inheritance often leads to conditions that predominantly affect males, as they have only one X chromosome, making them more susceptible to recessive disorders carried on this chromosome.
CGG trinucleotide repeat expansion is a genetic mutation where the cytosine-guanine-guanine (CGG) sequence is abnormally repeated within the FMR1 gene, leading to disorders like Fragile X syndrome. This expansion can disrupt normal gene function and is often associated with neurological and developmental issues.
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Intellectual disability is characterized by significant limitations in both intellectual functioning and adaptive behavior, originating before the age of 18. It affects everyday social and practical skills, requiring tailored support for individuals to achieve their full potential in daily life.
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Autism spectrum disorders (ASD) are a group of neurodevelopmental conditions characterized by challenges in social interaction, communication, and the presence of repetitive behaviors or restricted interests. The spectrum nature of ASD means that symptoms and severity can vary widely among individuals, necessitating personalized approaches to support and intervention.
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Epigenetics refers to the study of heritable changes in gene expression that do not involve alterations to the underlying DNA sequence. These changes are influenced by various factors including environment, lifestyle, and disease, and can have significant implications for development, health, and evolution.
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Genetic counseling is a process that involves evaluating family history and genetic information to assess the risk of inherited conditions, providing individuals and families with guidance and support in understanding and making informed decisions about their genetic health. It plays a critical role in personalized medicine, helping to identify potential genetic disorders and offering options for management, prevention, and family planning.
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Molecular diagnosis involves the detection and analysis of nucleic acids, proteins, and other molecular markers to diagnose diseases, predict disease progression, and tailor individualized treatment plans. It leverages advanced technologies such as PCR, next-generation sequencing, and microarrays to provide precise and early disease detection, often before clinical symptoms appear.
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Neurodevelopmental disorders are a group of conditions that manifest early in development, often before a child enters grade school, and are characterized by developmental deficits that produce impairments of personal, social, academic, or occupational functioning. These disorders may involve dysfunction in the central nervous system, affecting cognitive, motor, and emotional skills, and can include conditions such as autism spectrum disorder, ADHD, and intellectual disabilities.
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Trinucleotide repeats are sequences of three nucleotides that are repeated consecutively in the genome, and their expansion beyond a normal range is associated with several genetic disorders. These expansions can lead to the disruption of normal gene function, resulting in diseases such as Huntington's disease and Fragile X syndrome.
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Premutation carriers are individuals who have a genetic alteration in the form of an increased number of CGG repeats in the FMR1 gene, which can lead to various health issues. While they do not exhibit the full mutation associated with Fragile X syndrome, they may experience related conditions such as Fragile X-associated tremor/ataxia syndrome (FXTAS) or primary ovarian insufficiency (FXPOI).
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Genetic anticipation is a phenomenon where certain genetic disorders manifest at an earlier age and with increased severity in successive generations. It is often associated with the expansion of unstable DNA repeat sequences, such as trinucleotide repeats, within specific genes.
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CGG repeat expansion is a genetic mutation where the trinucleotide sequence CGG is repeated excessively within a gene, often leading to disorders such as Fragile X syndrome. This expansion disrupts normal gene function, typically through mechanisms like gene silencing or altered protein production.
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The FMR1 gene premutation is a genetic alteration involving an increased number of CGG repeats in the FMR1 gene, which can lead to disorders such as Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) and primary ovarian insufficiency. Individuals with the premutation are at risk of passing on a full mutation to their offspring, which can result in Fragile X syndrome, a leading cause of inherited intellectual disability.
Trinucleotide repeat expansion is a genetic mutation where specific sequences of three nucleotides are repeated excessively, leading to various hereditary disorders. This phenomenon can cause diseases such as Huntington's disease and fragile X syndrome, where the number of repeats correlates with disease severity and onset.
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Repeat expansion refers to the phenomenon where certain DNA sequences, known as tandem repeats, become longer due to abnormal replication processes. This genetic mutation is associated with several hereditary disorders, including Huntington's disease and fragile X syndrome, where the length of the repeat correlates with disease severity and onset.
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder affecting older adult carriers of the FMR1 premutation, characterized by intention tremor and gait ataxia. It is caused by the expansion of CGG repeats in the FMR1 gene, leading to RNA toxicity and neuronal damage.
Trinucleotide repeat disorders are a group of genetic conditions caused by the abnormal expansion of repetitive DNA sequences, leading to a range of neurological and physical symptoms. These disorders are characterized by the anticipation phenomenon, where the severity of the condition increases and the age of onset decreases in successive generations.
Concept
DNA repeat expansion refers to the abnormal increase in the number of repeated sequences within the DNA, which can lead to genetic disorders by disrupting gene function or protein production. This phenomenon is particularly significant in the context of neurodegenerative diseases, where expanded repeats can cause proteins to misfold or aggregate, leading to cell death.
Concept
The FMR1 premutation involves having between 55 to 200 CGG repeats in the FMR1 gene on the X chromosome, which can lead to conditions like Fragile X-associated tremor/ataxia syndrome (FXTAS) and Fragile X-associated primary ovarian insufficiency (FXPOI). Carriers of the premutation may not have full Fragile X syndrome but can pass on the condition and may experience related health issues.
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