Part I: Lecture 24 Flashcards
AR inheritance: WT allele
A
AR inheritance: mutant allele
a
AR inheritance: a/a
affected
AR inheritance: A/a
carrier
AR inheritance: A/__
status unknown
How to know if it is AR inheritance
-appears in offspring of unaffected parents
-affects males and females
mendelian ratios in humans
1/4 chance of disease ≠ 1 in 4 children have disease
humans have small number of children
Phenylketonuria (PKU) gene affected
PAH gene
PAH gene makes ___ which does what?
phenylalanine hydrolase
turns Phe into Tyr
without PAH, PHE becomes ___ which does what?
phenylpyruvic acid
damages the CNS
result of PAH-/PAH- mutations
fetuses protect in utero – mother gets rid of excess Phe
infant has to live on low Phe diet for life
low Phe diet
vegetarian diet
no meat and some grains
disorders are recessive when ___
heterozygote has WT phenotype (50% of gene activity is sufficient)
most mutations in enzyme coding genes are ___ because __
recessive because 50% of enzyme activity is sufficient
some genes have many ___
mutant alleles
compound heterozygote (def.)
2 different mutant alleles
AD inheritance: WT allele
a
AD inheritance: mutant allele
A
AD inheritance: A/a
affected
AD inheritance: A/A
affected to the same or greater extent (often non-viable)
How to know if it is AD inheritance
-found in each generation
-affects males and female equally
-father-> son transmission is possible
Achndroplasia gene affected
FGFR3 gene
FGFR3 gene encodes a ___
receptor for a negative growth factor that prevents cell reproduction and prevent growth of limb bones in fetus
mutant allele of FGFR3 gene produces ___
overactive protein that switches immature bone cell to mature cell, preventing growth = short limbs
disorders are dominant when ___
heterozygote has mutant phenotype
AD disorders when homozygous mutant allele leads to non-viable fetus, the mutant allele is ____ to WT allele
incompletely dominant with (heterozygote phenotype is in between two homozygous phenotype)
