Disorders of Development Congenital – Birth Defects
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Disorders of Development Congenital – Birth Defects






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    Disorders of Development Congenital – Birth Defects Disorders of Development Congenital – Birth Defects Presentation Transcript

    • Disorders of Development Congenital – Birth Defects Congenital – Teratogenic Agents Trisomy Disorders William’s Syndrome Autism
      • Birth Defects occur during Critical Periods in Development
      • 1. Defects during Zygote are aborted;
      • 2. Defects in the remaining prenatal period are irreversible;
      • 3. Critical Periods: a time of rapid change in the development of the organism (i.e., system or structure) and if interrupted will result in permanent congenital abnormalities.
      • Sensitive periods in development
      • 1. Occur prenatally and less irreversible
      • 2. Interference will disrupt growth; may result in subtle dysfunctions
      • 3. Continues into post-natal period
      • Teratogens
      • - Agents that cause congenital malformations in critical periods, and subtle alterations in the brain during sensitive periods
    • Critical Period Defect: Cleft Palate
      • Irreversible congenital abnormality affecting a critical period (palate development) during the embryonic and early fetal stages
      • May affect pituitary growth as the palate and anterior pituitary are derived from the same embryonic tissue.
    • Critical Period Defect: Anencephaly (absence of brain) Failure for the brain to grow beyond the rhombencephalon. Neonate failed to survive.
    • Critical Period Defect: Schizencephaly Developmental of the brain affected during the fetal period (i.e., growth of the forebrain). Cells either failed to migrate or ventricular region failed to close.
    • Teratogens Agents that cause congenital malformations
    • Fetal Alcohol Syndrome Features : Growth retardation, neurodevelopmental abnormalities (fine motor skills, LD, behavior disorders, and mental retardation in 50%). Facial dysmorphia during embryonic period (week 4-8), CNS problems during the fetal period (migration problems, smaller dendrites, few neurons in brain regions)
    • Genetic Conditions: Chromosomal Abnormalities
      • Trisomy 21 (Down’s Syndrome)
      • Trisomy of other chromosomes
        • Edward’s Syndrome (Trisomy 18)
        • Patau’s Syndrome (Trisomy 13)
    • Trisomy 21: Down’s Syndrome Non-disjunction of the 21 st Chromosome
    • Anatomical Dysmorphia & Risk (Increase with Maternal Age) Just 1%-20% graphed here
    • How does Trisomy 21 happen? First, normal development… In normal development mitosis proceeds normally from the first cell division
    • In Down’s Syndrome, non-disjunction of the 21 st chromosome can happen at the first cell division
    • Non-disjunction of the 21 st chromosome cab occur after the first cell division resulting in a mosaic form of Down’s Syndrome
    • Faulty distribution can occur in the egg or sperm when the mother or father is a carrier.
    • Trisomy 18 – Edward’s Syndrome
    • Some Features of Edward’s Syndrome
      • Facial: microcephaly, low set malformed ears
      • Skeletal: webbed neck, overlapping of fingers and fixed flexion of fingers
      • CNS: severe mental retardation, neural tube defect, ocular abnormalities
      • Respiratory: apnea
      • Cardiovascular problems
      • Gastrointestinal and genitourinary problems
      • Life Span: death by 12-24 months (very few reach adulthood)
      • Incidence: 0.2/1000 births
    • Trisomy 13: Patau’s Syndrome
      • Features:
      • 0.1/1000 births
      • Spina bifida & cleft palate
      • CNS: underdevelopment of frontal lobe (fails to divide) and corpus callosum
      • Profound Mental Retardation
      • Extra fingers and toes, deaf
      • Life Span: 82% die in the first month, 5-10% die in first year.
    • Williams Syndrome – Partial Deletion of the 7 th Chromosome
      • Features:
      • 1 in 20,000 births
      • Neurodevelopmental delays, cognitive deficits, LD, ADHD
      • Overly friendly, social
      • Extremely empathic
      • Low muscle tone
      • Extremely sensitive hearing
    • Brain Areas Affected : Amygdala activates more for threatening scenes and very little for threatening faces. This accounts for absence of anxiety in interpersonal interactions (no fear, hence over friendliness). Also, abnormal activity in frontal lobe and a disconnect with the amygdala (except for medial-prefrontal which is linked to empathy and the only structure still connected to the amygdala) Normal Control Williams Syndrome Amygdala
    • Genetic Abnormality of Chromosome 7: 21 genes missing Elastin protein, made only during the prenatal period, is absent and causes vascular problems during life; the missing elastin gene is use to identify the 21 missing genes in Williams Syndrome.
    • Autism
      • A neurodegenerative disorder characterized by impairment in social interaction and communication.
      • Age of onset: typically between ages 2 and 4 (sometimes earlier)
    • Symptoms
    • Theories for Etiology and CNS Problems
      • Genetic alterations
      • Prenatal exposure to toxins and/or viruses
      • Maternal and fetal immune interactions
      • Vaccination with mercury base
      • Amygdala less active and area is smaller
      • Hippocampus is smaller
      • Frontal areas (medial prefrontal region) less active
      • Less activity in the superior temporal sulcus (involved in understanding others)
      • Larger & heavier brain suggests apoptosis failure
    • Microglia Activation in Autism (white matter of the cerebellum) Microglial cells
    • Brain Areas Affected in Autism: Fusiform Face Area (FFA), Amygdala, Left Frontal Lobe, Left Temporal Lobe, and Cerebellum
    • References for Photos (slides 5,6,9,11,16,18,19,22-25)
      • http://images.google.com/imgres?imgurl=http://www.hallym.or.kr/~kdcp/ cytogenetics / cytogen - ds .files/c6_cleft_lip. jpg &imgrefurl=http://www.hallym.or.kr/~kdcp/ cytogenetics / cytogen - ds . htm &h=483&w=316&sz=61&tbnid=9z1GFXy5kykJ:&tbnh=126&tbnw=82&hl=en&start=61&prev=/images%3Fq%3DWilliams%2BSyndrome%26start%3D60%26svnum%3D10%26hl%3Den%26lr%3D%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official_s%26sa%3DN
      • h ttp ://images.google.com/imgres?imgurl=http:// cas . bellarmine . edu / tietjen / HumanBioogy /Finished%2520Images/gen12.gif&imgrefurl=http:// cas . bellarmine . edu / tietjen / HumanBioogy /bills_developmental_abnormalities. htm &h=383&w=400&sz=117&tbnid=KbFuC4QsI4sJ:&tbnh=114&tbnw=120&hl=en&start=3&prev=/images%3Fq%3DEdward%2527s%2BSyndrome%26svnum%3D10%26hl%3Den%26lr%3D%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official_s%26sa%3DG
      • http://images.google.com/imgres?imgurl=http://www. cmu . edu / cmnews /extra/extra_art/Just_Fig1. jpg &imgrefurl=http://www. cmu . edu / cmnews /extra/extra_art/&h=421&w=150&sz=25&tbnid=0aXX65rnVysJ:&tbnh=122&tbnw=43&hl=en&start=189&prev=/images%3Fq%3Dautism%2Bbrain%26start%3D180%26svnum%3D10%26hl%3Den%26lr%3D%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN
      • http://www. altcorp .com/ DentalInformation / autismcytokines . htm
      • http://www. neuro . jhmi . edu / neuroimmunopath /Microglia%20pictures/5_lg. jpg
      http://images.google.com/imgres?imgurl=http://www. fetalalcohol .com/images/face- thm .gif&imgrefurl=http://www. fetalalcohol .com/what-is- fase . htm &h=260&w=304&sz=16&tbnid=RpmOv4g5G04J:&tbnh=95&tbnw=112&hl=en&start=6&prev=/images%3Fq%3DFetal%2BAlcohol%2BSyndrome%26svnum%3D10%26hl%3Den%26lr%3D%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official_s%26sa%3DG   http://images.google.com/imgres?imgurl=http://www.infobiogen.fr/services/chromcancer/IntroItems/Images/tri21FaceEng.gif&imgrefurl=http://www.infobiogen.fr/services/chromcancer/IntroItems/PolyTri21Eng.html&h=429&w=463&sz=50&tbnid=XGXbYU9uVcYJ:&tbnh=115&tbnw=125&hl=en&start=1&prev=/images%3Fq%3DTrisomy%2B21%2Bface%26svnum%3D10%26hl%3Den%26lr%3D%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official_s%26sa%3DG