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Chromosomes - Coggle Diagram

- - - - Deletion, Duplication
      - Translocation (balanced/unbalanced)
      - Inversions, Ring chromosomes
    - - Triploidy (69)
      - Tetraploidy (92) – usually incompatible with life
    - - Aneuploidy (Trisomy, Monosomy, Nullisomy)
      - Examples: Trisomy 21 (Down), Trisomy 18 (Edwards), Trisomy 13 (Patau)
        
        Down Syndrome
        
        Discovered
        
        ohn Langdon Down, 1866
        
        Gene involvement
        
        300+ genes on Chr 21
        
        Definition
        
        genetic disorder, trisomy 21
        
        Global prevalence:
        
        1 in 700 births
        
        6 million worldwide
        
        3000–5000 annual US births
        
        Affects all populations
        
        Types of Down Syndrome
        
        Robertsonian Translocation (3–4%)
        
        Carrier parent = 45 chromosomes but normal phenotype
        
        Genetic counseling required
        
        Chr 21 attaches to 14 or 22
        
        Mosaicism (1–2%)
        
        From mitotic nondisjunction post-fertilization
        
        Milder phenotype, diagnosis harder
        
        Normal + trisomic cells
        
        Nondisjunction (95%)
        
        Meiosis II (25% of cases)
        
        Maternal origin ~90%
        
        Meiosis I (75% of cases)
        
        Risk ↑ with maternal age (25 yrs 1/1250 → 45 yrs 1/30)
        
        Clinical Features & Complications
        
        Gastrointestinal
        
        Duodenal atresia (5–7%)
        
        Hirschsprung disease (1%)
        
        Endocrine
        
        Hypothyroidism (15–20%)
        
        Type 1 diabetes (↑10-fold risk)
        
        Cardiac (50%)
        
        AVSD (43%)
        
        VSD (32%)
        
        Neurological & Sensory
        
        Hearing loss (75%)
        
        Vision disorders (refractive errors, cataracts, strabismus)
        
        intellectual disability (IQ 50–70)
        
        Intelligence Quotient. It's a score derived from a set of standardized tests designed to assess a person's human intelligence.
        
        4 more items...
        
        Medical Management (Across Lifespan)
        
        Infancy (1–12 mo):
        
        growth monitoring, immunizations, developmental intervention
        
        Childhood (1–12 yrs):
        
        thyroid yearly, hearing every 2 yrs, sleep study, education support
        
        Birth–1 month
        
        echo, thyroid test, CBC, vision, hearing
        
        Adolescence–Adult:
        
        transition plan, reproductive counseling, dementia screening, chronic disease management
        
        Longevity & Adult Health
        
        Reproductive health:
        
        Males: infertility
        
        Females: fertility possible but ↑ risk of affected offspring
        
        Alzheimer’s risk
        
        (APP gene, amyloid-β buildup by age 30–40)
        
        Social integration:
        
        nclusion, supported employment, independent living
        
        in Qatar
        
        2 more items...
        
        Life expectancy
        
        now into 60s with modern care
        
        Future & Research
        
        Gene therapy
        
        correcting gene imbalance
        
        Precision medicine
        
        genomic analysis for personalized care
        
        Anti-amyloid treatments
        
        for Alzheimer’s
        
        Early intervention
        
        developmental programs with lasting benefits
        
        Cognitive therapies
        
        EGCG, donepezil
    - - Turner (45,X)
      - Klinefelter (47,XXY)
      - Triple X (47,XXX)
  - - - 10-14 weeks
      - Maternal blood, ultrasound
      - What is tested?
        
        Nuchal translucency
        
        PAPP-A
        
        hCG
      - Tests for?
        
        T21,T18,T13
    - - 10 weeks onwards
      - Maternal blood test
        
        Traces of fatal DNA fragments
      - Tests for?
        
        T21,T18,T13
        
        Sex abnormalities
    - - 15-22 weeks
      - Maternal blood test
        
        AFP marker
        
        Low
        
        High
      - Tests for?
        
        T21,T18
        
        Neural tube defects
    - - Diagnostic
        
        Slight risk of miscarriage
        
        Definitive
        
        Invasive (fetal cells or tissue)
        
        Ex.
        
        Chorionic villus sampling
        
        Amniocentesis
      - Screening
        
        Safe
        
        Risk estimation
        
        Non-invasive (meternal blood)
        
        Ex.
    - - Genetic counseling
        
        Autonomy
        
        Adoption
        
        Ending the Pregnancy
        
        Continuing the Pregnancy
        
        Translate complex genetic information into clear, understandable language.
        
        Provide psychosocial support to help individuals and families cope with the emotional impact of a genetic diagnosis or risk.
        
        Petion's reaction
        
        Patients may experience sudden and intense emotions
        
        Some patients may deny the seriousness of the news
        
        fear of the unknown
        
        shut down,
        
        Determine the likelihood of inherited conditions
        
        Educate individuals and families about specific genetic conditions,
  - - - Mosaicism
      - De novo
      - Paternal age
      - Parental karyotype/carrier status
      - Maternal age (major)
      - all factor
    - - Cause of previous abnormality
        
        Sporadic
        
        1% higher risk
        
        Inherited
        
        Much higher risk
- - - - 1 sample preparation
      - 2 DNA denaturation
      - 3 Probe hybridization
      - 4 Wash away excess probe
      - 5 Microscopy
    - - 2 dots = normal (diploid)
      - 1 dot = deletion/monosomy
      - 3 dots = duplication/trisomy
      - Juxtaposed signals = translocation
  - - - 1 RNA or DNA extracted from cells/tissues
      - 2 For gene expression, RNA → cDNA via reverse transcription
      - 3 Sample is fluorescently labeled and applied to the microarray
      - 4 Hybridization occurs where the sample binds to complementary probes
  - - - Denaturation (≈95 °C): DNA strands separate
      - Annealing (≈55–65 °C): Primers bind to target
      - Extension (72 °C): Taq polymerase synthesizes DNA
  - - - procedure
        
        steps
        
        2 Cell culture
        
        3 Arrest in metaphase
        
        4 Hypotonic treatment
        
        5 Fixation
        
        6 Slide preparation
        
        7 Staining
        
        8 Microscopy & analysis
        
        1 Sample collection