Download Sex-Linked (AKA X-Linked) Disorders

PSY 202/Schaffer
Machida/Spring 2003
Chapter 3: Heredity Influences on Development
I.
Gene Express: Probability
A. Recessive Inheritance
PKU
Tay Sachs
B. Co-dominance: AB Blood Type
C. Incomplete: Sickle Cell Anemia
D. Sex-Linked Inheritance
Color Blindness
Fragile X Syndrome
-Most common inherited cause of mental
retardation
-Symptoms begin to surface in early
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childhood
-80% of males/sons are affected
-IQ declines over the first 10 years of
life
-Females/daughters have normal IQ or
some learning disabilities
-Common Features
*speech outbursts
*noticeable physical deformities
especially after puberty
*hyperactivity
*tantrums
*autistic like
*other physical features
big ears
large testicles
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II. Genetic Imprinting
One of the pair of alleles from a parent
Is expressed, but doesn’t follow the typical
Rules of expression.
A. Father’s allele – child develops diabetes
B. Mother’s allele – child develops
Angelman’s Disorder
III.
Detection:
A. Recessive Disorders: Tay Sachs
B. Various methods
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IV. Methods of Study Hereditary Influences
A. Behavioral Genetics
Degree of concordance between
Monozygotic vs. Dyzygotic Twins
Vs. Non-Twin Siblings
Heritability Estimates
Identical twins have higher heritability
Correlations than fraternal twins
Nonshared Environment = 1-identical twins
Reared together (high correlation)
IV. Hereditary and Environment
Contributions to Development
A. Canalization Principle
B. Range of Reaction Principle
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