whole general disease summary Flashcards
Describe muscular dystrophies
A group of genetic disorders causing muscle weakness and wasting, categorized into congenital muscular dystrophies affecting molecules interacting with dystrophin and muscularrophies affecting dystin directly.
What are the two types of muscular dystrophies?
Congenital muscular dystrophies and muscular dystrophies
Define congenital muscular dystrophy and its association with laminin
Congenital muscular dystrophy is linked to laminin, a protein in the basement membrane of skeletal muscle cells that helps hold cells together and attached to surrounding structures.
How does absence or in-frame deletions of laminin α2 chains contribute to congenital muscular dystrophy?
Absence or in-frame deletions result in poor binding to dystroglycan and weak binding to integrins, affecting muscle stability.
Why is the disruption of integrins a problem in muscular dystrophies?
Disruption of integrins leads to loss of structural integrity, impaired cell signaling, muscle fiber instability, and compromised transmission of force at myotendinous junctions.
Describe the genetic mutations causing muscular dystrophies
Muscular dystrophies are caused by genetic mutations in the dystrophin gene, a large gene on the X chromosome with 79 exons and 2 million base pairs.
How does the absence of dystrophin in Duchenne muscular dystrophy differ from misshapen dystrophin in Becker muscular dystrophy?
Duchenne has no dystrophin due to nonsense or frame shift mutations, while Becker has misshapen dystrophin allowing some functional dystrophin production.
Why is the absence of dystrophin a problem in muscular dystrophies?
Absence of dystrophin leads to unstable sarcolemma, cell death, muscle fibrosis, and atrophy due to the loss of structural support and stability.
Describe the diagnostic methods for muscular dystrophies
Diagnosis involves clinical signs like waddling gait, blood tests for elevated creatine kinase, genetic testing for dystrophin and laminin genes, and muscle biopsy showing connective tissue changes and muscle degeneration.
What are the treatment options for muscular dystrophies?
Treatment includes physiotherapy for quality of life, glucocorticoids to slow degeneration, and potential therapies like gene therapy and exon skipping to introduce functional dystrophin genes.
Describe the strategy of using aminoglycosides to bypass premature stop codons in genetic disorders.
Aminoglycosides can help restore dystrophin in some cases by allowing the ribosome to read through premature stop codons.
Define stem cell therapy in the context of muscle tissue regeneration.
Stem cell therapy involves transplanting stem cells to regenerate damaged muscle tissue.
How is collagen synthesized in the body?
Collagen synthesis involves transcription and translation of collagen mRNA into pre-collagen, followed by post-translational modifications like hydroxylation, glycosylation, and formation of the triple helix.
Describe the characteristics of connective tissue disorders related to collagen types 1-5.
Connective tissue disorders involve collagen types 1-5, with specific roles in skin, tendons, organs, bones, cartilage, reticular fibers, basal lamina, cell surfaces, hair, and placenta.
What are the diagnostic methods and treatments for Ehlers-Danlos syndrome?
Diagnostic methods for Ehlers-Danlos syndrome include examining symptoms, joints, skin, and genetic testing. Treatments may involve supportive care like physiotherapy and orthopaedic instruments.
Explain the characteristics and genetic basis of Osteogenesis imperfecta.
Osteogenesis imperfecta is characterized by low bone mass, increased bone fragility, and mutations in COL1A1 or COL1A2 genes affecting collagen production. It is diagnosed through genetic testing and X-rays, with treatments focusing on bone health.
Describe the clinical features and genetic mutation associated with Marfan’s syndrome.
Marfan’s syndrome presents with tall stature, long limbs, heart, eye, lung, and skeletal issues due to a mutation in the FBN1 gene on chromosome 15, affecting fibrillin 1 production.
What are ion channels and their importance in physiological processes?
Ion channels are integral membrane proteins that allow ions to pass through cell membranes, influencing processes like muscle contraction and neuronal communication by maintaining membrane potentials.
How do ligand-gated ion channels function, and what neurotransmitter activates them?
Ligand-gated ion channels, like GABA receptors, are activated by neurotransmitters such as GABA, leading to the opening of chloride channels and an inhibitory effect.
Explain the role of voltage-gated ion channels and their activation mechanism.
Voltage-gated ion channels open in response to membrane potential depolarization, allowing ions like sodium to enter the cell. They are stimulated by neurotransmitter binding to receptors causing depolarization.
Describe how channelopathies arise.
Channelopathies arise mainly from genetic mutations affecting ion channels, which can lead to gain of function or loss of function mutations. These mutations can occur in the promoter region, coding sequence, ligands, or modulators of ion channels.
Define channelopathies.
Channelopathies are diseases of ion channels, most of which are monogenic diseases caused by mutations. They can result in various types of mutations that affect the function of channels.
How do skeletal muscle channelopathies like myasthenia gravis affect muscle contraction?
In myasthenia gravis, the immune system attacks nicotinic acetylcholine receptors on muscle cells, preventing them from binding acetylcholine and causing muscle weakness and fatigue from repetitive movements.
Explain myotonia congenita and how it affects muscle contraction.
Myotonia congenita is characterized by muscle contraction without the ability to relax. It can be caused by mutations in Na+ or Cl- channels, leading to delayed relaxation and sustained muscle contraction.
Describe how neuropathic pain is transmitted and perceived.
Neuropathic pain is transmitted through sensory neurons with cell bodies in the dorsal root ganglion. It is perceived due to changes in neurotransmitter release and receptor activity, leading to increased sensitivity to pain and abnormal pain responses.
How do Na+ ion channels, specifically NAV1.7, contribute to extreme pain disorders?
NAV1.7 channels, encoded by SCN9A, can mutate to cause gain of function, resulting in persistent ion currents and extreme pain disorders like erythromelalgia. Loss of function mutations in NAV1.7 can lead to insensitivity to pain.
