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Genetics & Prenatal Development

Genetics & Prenatal Development. 2/13/07. Prenatal Influences on Development. Both genetic and environmental factors influence prenatal development Emphasis on how biological factors affect social, emotional and cognitive development rather than physical development itself. Genetics.

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Genetics & Prenatal Development

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  1. Genetics & Prenatal Development 2/13/07

  2. Prenatal Influences on Development • Both genetic and environmental factors influence prenatal development • Emphasis on how biological factors affect social, emotional and cognitive development rather than physical development itself

  3. Genetics • Genotype refers to the genetic information that determines inherited characteristics • Phenotype refers to directly observable characteristics • more than one genotype can result in the same phenotype • Chromosomes are made up of DNA • 23 sets • 22 pairs of autosomes • 1 pair of sex chromosomes (XX or XY)

  4. Mechanisms of Inheritance • Polygenic • Single gene • Blended • Some characteristics, only phenotype matters; others, genotype as well • Sex-linked characteristics are on the X chromosome • Genes and environment combine to determine expression of some genes • Scarr-McCartney model of bidirectional influence

  5. Nature Vs. Nurture • Genes predict a possible range of outcomes, they do not dictate and exact outcome • Reaction Range • Canalization • Gene environment correlation (e.g., niche picking) • Twin studies: comparing MZ with DZ twins • Even MZ twins discordant for some behaviors • Genes help us “choose” environment • Adoption Studies • Compare whether child more like biological or adoptive family • Historically, self selection of who adopts

  6. Inherited Conditions Down Syndrome PKU Cystic Fibrosis Tay Sachs Disease Conditions presumed at least partly inherited Depression Diabetes Schizophrenia Obesity Common Inherited Disease of Childhood

  7. Behavioral Genetics studies contributions of both heredity & environment to diversity of human characteristics Environmental Effects The special case of maternal stress during pregnancy (or maternal genetic high anxiety) Hormonal changes change fetal environment Stress management or social support intervention with pregnant women improved birth weight of babies (22% control, 9% treatment group had low birth weight babies)

  8. Prenatal Development • Conception • Multiple births: maternal age, ethnic background, family history, environmental temperature, all increase likelihood • Germinal period (1-2 weeks) • Embryonic Stage (2-8 weeks) • Fetal Stage (3rd month until birth)

  9. Sex Differentiation • Sperm may be X or Y • All fetus’ initially develop gonad tissue (undifferentiated) • At about 7 weeks, if Y, testes develop and begin to secrete testosterone which inhibits development of female sex organs • 3 different genes identified • One switches on hormones • Two others drive organ development

  10. Brain Development • Around 5th month, sucking, blinking observed • About 6-7 months, fetus can feel pain (physiological changes, unclear if there is any perception) • 8th month, recognize different voices and after birth, respond to familiar vs. unfamiliar differently

  11. Protecting the developing human • Placenta • Vulnerable periods • Teratogens (agents that damage fetus) • Tobacco • Alcohol • Medications • Chemicals • Radiation

  12. High Risk Pregnancy • Teen Pregnancy • Older women • Medical conditions • Preterm delivery • Questions associated with prenatal diagnosis of specific conditions

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