2 Mendelian and Mitochondrial Inheritance Flashcards
what is unit inheritance?
parental phenotypes do not blend
segregation?
only one copy of each pair of genes is passed on
achondroplasia:
-inheritance?
-symptoms
-
- dominant
- short arms, legs, large head
- intelligence and life span normal
what is a tell tale sign of daminant inheritance on a pedigree?
every generation effected
what is variable expressivity?
the disease or condition can present with different or varying phenotypes (Marfans)
Marfans:
- inheritance
- physiology
- mortality
- mendel dominant
- connective tissue disorder, bone overgrowth and join laxity
- ruptured aorta
what is incomplete penetrance?
not everyone with the mutation will produce the phenotype (BRCA, and many other cancer mutations)
when are new (de novo) mutations common?
- occur at hot spots in the genome
- more common when the father is older, his sperm will begin to acrew more mutations
cystic fibrosis: -inheritance? -systems effected? -reproductive issues? -
- recessive
- primarily lung and GI
- 95% of males are infertile due to flagella not functioning (Cl channel required)
if only one generation is affected on the pedigree, what could this mean?
recessive inheritance
recessive traits have less variability than dominant traits T/F
True, and penetrance is usually complete
Sickle Cell Anemia:
- inheritance
- ethnic predis
- clinical manifestation
- autosomal recessive
- prominent in african americans
- pain crises, organ damage
hemophilia: -inheritance -deficiency in what protein -where does bleeding occur -
- X linked recessive
- def in factor 8 or 9 depending on type
- internally, in joints or muscles
are females or males more likely to be affected by x linked recessive disorders?
males
what transmission is not possible in x linked recessive disorders?
male to male
what is lyonization?
the inactivation of one x chromosome in female cells
-this could be random (50/50) or skewed, leading to a phenotype in carriers of an x linked recessive condition
Duchenne muscular dystrophy:
- inheritance
- symptoms
- x linked recessive
- progressive degen of skeletal muscle, seemingly hypertrophic
would a female karyotype of 45, X leave this woman more susceptible to x linked recessive diseases?
yes
in what scenarios are females affected by X linked recessive traits?
- has a 45, X karyotype
- skewed X inactivation
- affected father and carrier mother (rare)
- the condition may also have a non-x-linked cause
incontinentia pigmenti:
- inheritance
- systems effected
- symptoms
- x linked dominant
- skin, hair, nails, eyes, and CNS. Skin lesions, alopecia, hypodontia, cognitive delays/disabilities
are males or females more likely to be affected by x linked dominant inheritance?
Females
-often lethal in males
where are the genes for ox phos found?
nuceleus, not the mitochondria
where do the mitochondrial genes come from
mother’s oocyte, not father’s sperm
what is MELAS?
- inheritance
- features
- mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes
- hearing loss, diabetes, seizures, intellectual disability
what is heteroplasmy?
a mixture of normal and abnormal mitochondria in the cytoplasm
what is homoplasmy?
all mtDNa is the same (abnormal or normal)
how are mitochondria segregated during mitosis?
randomly
what is the threshold effect with regard to mitochondrial disorders?
you need a certain number of malfunctioning mitochondria to express a phenotype. this phenotype may also vary depending on the % of abnormal mtDNA
how can the percentage of abnormal mtDNA change over time in different tissues?
- random genetic drift
- selective (replicative) advantage
how does age affect mitochondria?
- decreases with age thought is that there is oxidative damage from ox phos or an increased mutation rate
- if you have a mitochondrial disease it gets worse with age
- mitochondria might have a large effect on age in general
what tissues are effected most by mitochondrial diseases?
- tissues that require a lot of energy
- brain and muscle
what might be necessary in order to diagnose mitochondrial disorders?
muscle biopsy
if a diagnosis is made prenatally, what is the difficulty with determining prognosis?
heteroplasmy
what is nuclear transfrer?
a nucleus is removed from an oocyte with healthy mitochondria and discarded and then the nucleus is removed from an oocyte with abnormal mitochondria and placed inside the oocyte with abnormal mitochondria
