International Genetics and Genomics of Diseases

 DNA Repair Pathways DNA repair pathways are a collection of cellular mechanisms that detect and correct damage in DNA to maintain genome integrity and ensure proper cellular function. DNA damage can arise from internal processes such as replication errors and oxidative stress, or external factors like radiation and chemical exposure. To counteract this, cells employ several highly coordinated repair systems, including base excision repair (BER) for small base lesions, nucleotide excision repair (NER) for bulky DNA damage, mismatch repair (MMR) for replication errors, and double-strand break repair pathways such as homologous recombination (HR) and non-homologous end joining (NHEJ) . These pathways play a critical role in preventing mutations, maintaining genomic stability, and reducing the risk of diseases such as cancer. DNA Repair Pathways DNA Damage Repair Base Excision Repair (BER) Nucleotide Excision Repair (NER) Mismatch Repair (MMR) Homologous Recombination (HR) Non...

 Genetic Transformation in Plants Genetic Transformation in Plants is a biotechnology process where foreign DNA is deliberately introduced into a plant’s genome to modify its characteristics. This is commonly achieved using methods such as Agrobacterium-mediated transformation or biolistic (gene gun) delivery . The inserted genes can confer beneficial traits like pest resistance, herbicide tolerance, improved nutritional value, and enhanced stress tolerance (drought, salinity, etc.). This technology is widely used in crop improvement, functional genomics, and sustainable agriculture, leading to the development of genetically modified (GM) crops that contribute to food security and agricultural efficiency. Plant genetic engineering Transgenic plants Agrobacterium tumefaciens Gene gun (biolistics) Recombinant DNA technology Crop improvement Trait enhancement Gene expression Transformation efficiency Selectable markers Tissue culture Plant biotechnology #PlantTransformation#Genet...

Autosomal Dominant Inheritance Autosomal Dominant Inheritance is a genetic inheritance pattern in which a single copy of a mutated gene located on one of the autosomes ( non-sex chromosomes ) is sufficient to cause a trait or genetic disorder . In this pattern, an affected individual usually has one affected parent , and each child of an affected parent has a 50% chance of inheriting the mutation and expressing the condition. Because the gene is located on an autosome, the disorder affects males and females equally and can appear in every generation of a family. Autosomal dominant conditions often show a vertical transmission pattern in pedigrees, meaning the trait is passed from parent to child across successive generations. Examples of disorders that follow this inheritance pattern include Huntington's disease , Marfan syndrome , and Achondroplasia . Understanding autosomal dominant inheritance is important for genetic counseling, disease prediction, and family risk assessm...

 Non-Homologous End Joining (NHEJ) Non-Homologous End Joining (NHEJ) is a major DNA repair pathway responsible for repairing double-strand breaks (DSBs) in DNA. Unlike homologous recombination, NHEJ does not require a homologous DNA template. Instead, it directly joins the broken DNA ends together through a series of enzymatic steps involving end recognition, processing, and ligation. Key proteins involved in this pathway include the Ku70/Ku80 complex , DNA-PKcs , Artemis , and DNA ligase IV . NHEJ is active throughout the cell cycle and is particularly important in rapidly dividing cells . While it efficiently restores DNA integrity , it is considered an error-prone mechanism because small insertions or deletions may occur at the repair site. NHEJ also plays an essential role in immune system development through V(D)J recombination . Non-Homologous End Joining (NHEJ) DNA Double-Strand Break Repair DNA Damage Response Ku70/Ku80 Complex DNA-PKcs DNA Ligase IV Artemis Protein Genom...

 DNA Repair Mechanisms Diagram A DNA Repair Mechanisms Diagram visually illustrates the cellular pathways that detect and repair damage in DNA to maintain genome stability and prevent mutations. Cells are constantly exposed to DNA damage from environmental factors such as radiation, chemicals, and oxidative stress, as well as normal cellular processes like DNA replication . The diagram typically highlights the major repair pathways, including base excision repair (BER) for small base lesions, nucleotide excision repair (NER) for bulky DNA damage, mismatch repair (MMR) for replication errors, and double-strand break repair mechanisms such as homologous recombination (HR) and non-homologous end joining (NHEJ) . These pathways work together to preserve genetic integrity, reduce mutation rates, and prevent diseases such as cancer. DNA Repair Mechanisms DNA Damage Repair Base Excision Repair (BER) Nucleotide Excision Repair (NER) Mismatch Repair (MMR) Homologous Recombination (...

Microsatellite Instability Testing Genomic instability in cancer cells refers to the increased frequency of genetic alterations that occur during tumor development and progression. Unlike normal cells, cancer cells accumulate mutations, chromosomal rearrangements, copy number alterations, and aneuploidy at a significantly higher rate. This instability arises from defects in DNA repair pathways, replication stress, telomere dysfunction, and impaired cell cycle checkpoints. Genomic instability is a key driver of tumor heterogeneity, enabling cancer cells to adapt, evolve, and develop resistance to therapy. It contributes to the activation of oncogenes, inactivation of tumor suppressor genes, and the emergence of aggressive cancer phenotypes. Clinically, understanding genomic instability helps guide targeted therapies, immunotherapy decisions, and precision oncology strategies. Genomic Instability Cancer Cells Chromosomal Instability (CIN) Microsatellite Instability (MSI) DNA Damage D...