Mendelian disorders and multifactorial disease Flashcards
def. single gene disorders (mendelian)
- single gene mutations
- follow specific pattern of inheritance that can be followed in pedigree
what does pattern depend on
- function of protein
2. how mutation affects the protein
3 ways mutatation affects function
- gain of function
- loss of function
- disruption of multiprotein complex
features of auto. dom.
- passed from generations
- male and female
- male to male transmission
4 reasons disease occurs in autosomal dominant despite one normal gene
- haploinsufficiency - more than 50% needed
- dominant negative effect - abnormal protein interferes with normal protein
- mutation may enhance function of protein
- random somatic loss/mutation of other gene may occur
def. penetrance
proportion of indivs. with a mutation causing a disorder that show clinical signs of the disorder
how does penetrance work
- all or nothing
- may be explained by modifier genes in the individual
def. variable expressivity
example of ADs
FAP, marfans, polycystic kidney, achondroplasia
example of a reccesive
CF
features of recessive
- tend to be single sibship
- not usually in multiple generations
- both males and females
- both parents not usually affectes
why are heterosygotes normal when they have one abnormal gene in recessive dis. (2)
- half normal amount of product is enough
2. often enzymes, structural proteins without critical thresholds
X linked to know
duschenne muscular dystrphy
- muscle weakness
- calf hypertrophy
patho. of DMD
- gene encodes dystropin - role in maintenance of muscle membrane integrity
what will be seen in mother with germ cell mutation of DMD
germ-line mutation in all their cells
50% risk of son having
