polygenic
influenced by multiple genes (height, weight, IQ, personality)
A dominant trait can be due to ____ or ____
HOMOzygous: both are the same (HH, hh)
—OR—
HETEROzygous: both different (Hh)
examples of homozygous traits due one single dominant gene (Hh)
brown eyes, dark hair, farsightedness
most common
examples of homozygous traits due to 2 recessive genes (hh)
green/hazel/blue eyes, blonde hair, nearsightedness
an alternative form of a gene is called ______
an allele
Rutter’s family risk factors for child psychopathology
severe marital discord low SES overcrowding/large family size parent criminality MATERNAL psychopathology child placed outside home
Kauai study (Werner) positive outcomes for high risk infants due to:
canalization
genotype restricts phenotype to small number of outcomes
think “canal”
reaction range
status within the range depends on environmental factors
width of the range depends on genetic factors
genotype-environment correlations
critical periods vs sensitive periods
critical = specific and predetermined (e.g., imprinting goslings) sensitive = longer, more flexible; not closely tied to age or maturation stage
prenatal development
0-2 weeks: germinal stage (zygote)
3-8 weeks: embryonic stage (major structural damage if exposed to teratogens)
9 weeks-birth: fetal stage
Dominant gene disorders
single dominant gene from one parent
Huntington’s
Recessive gene disorders
2 recessive genes PKU cystic fibrosis Tay-Sachs sickle-cell
chromosomal disorders
variation in number or structure of chromosomes
aneuploidy
not correct number of chromosomes
Down = extra 21st
Klinefelter = 2 or more X with single Y (XXY, XXXY, etc)
Turner = female with single X
chromosomal deletion
part of chromosome missing
Prader-Willi
translocation
segment of chromosome transfers to another chromosome
sometimes in Down extra 21 is elsewhere
inversion
segment of chromosome breaks in 2 places, inverts and reattaches
Fetal Alcohol Spectrum Disorder (FASD)
FAS: most severe form
less severe:
*ARND: neuro disorder (no physical signs)
*ARBD: physical signs only (birth defects)
maternal conditions affecting baby
Rubella: heart defects, blind, deaf, ID
CMV: ID, hearing/visual impairments
HIV/AIDS: 20-30% transmission at birth; >1% if antiretrovial Rx used (50% survive to age 10)
malnutrition: low folic acid = neural tube defects
age of prematurity
less than 37 weeks
birthweight survivability
3.3 lbs (1500g)
SGA (small for gestational age)
below 10 %ile
develops less than normal rate
increased risk for asphyxia at birth, respiratory disease, hypoglycemia, LD, ADHD