mendelian Flashcards
exam 1
type of inheritance of achondroplasia
dominant inheritance
Achondroplasia
most common skeletal dysplasia
Male to male transmission is observed
dominant inheritance
features of a disorder vary between affected individuals, even in he same family
variable expressivity
Marfan syndrome is an example of variable ________
expressivity
what is marfan syndrome
systemic disorder of connective tissue
common characteristics of marfan
bone overgrowth, joint laxity, cardiovascular issues (dilated aorta)
not all individuals with a mutation have phenotypic effects
incomplete penetrance
example of incomplete penetrance
BRCA gene mutations
new gene mutations can occur and are often found at “ hot spot” in the genome
New (de novo)
80% cases are de novo
Achondroplasia
example of recessive inheritance
cystic fibrosis
what is cystic fribosis
multisystem disease, primarily involving pulmonary and digestive systems
1/25 Caucasians is a carrier
cystic fibrosis
usually only one generation is affected
autosomal recessive
less clinical variability than autosomal disorders
recessive inheritance
Sickle Cell Anemia has an
ethnic predisposition,
1/8 african americans are carriers
sickle cell anemia
sickle cell anemia is
characterized by intermittent pain crises and organ damage (due to vaso-occlusion) and chronic hemolytic anemia
Hemophilia occurs
internally, inot joints or muscles
bleeding disorder caused by deficiency in Factor VIII or Factor IX
hemophilia
male to male transmission is not observed
x-linked
“carrier” females may show mild expression of the trait
x-linked recessive
lyonization
x-inactivation
skewed X-inactivation may lead to ________ carriers
symptomatic
symptomatic females tend to be less severely affected than males due to skewed x-inactivation
x-linked recessive x inactivation
example of an x-inactivation affecting less in females
duchenne muscular dystrophy
Duchenne Muscular Dystrophy
progressive disease of the skeletal muscle results in delayed motor milestones
X-linked dominant inheritance
Incontinentia Pigmenti
incontinentia Pigmenti
disorder of the skin, hair, teeth, nails, eyes and central nervous system
_____ more likely than _______ to be affected in x- linked dominant
females are much more likely than males to be affected
all daughters of an affected male are affected
x-linked dominant
Major cause of mobility and mortality of cystic fibrosis
Pulmonary disease
Median life expectancy of cystic fibrosis
36.5 years
Two mutated gene copies are necessary for
expression of trait
Autosomal Recessive Inheritance
Males and females are (more/equally) likely to be affected in autosomal recessive inheritance
Equally
Ethnic predisposition may be noted
Autosomal Recessive Inheritance
Median life expectancy for those with sickle cell anemia
42-48 years
Life expectancy reduced
by ___ years due to hemophilia
10 years
Males are much more likely than females to
be affected
X-Linked Recessive Inheritance
All daughters of an affected male are carriers
X-Linked Recessive Inheritance
Due to Duchenne syndrome Dilated cardiomyopathy
typically occurs around ___ years
> 18 years
Life expectancy due to Duchenne
~27
Females may be affected by an X-linked Recessive Disorder in a few rare scenarios
– She has a 45,X karyotype
– She has an X chromosome rearrangement which results
in skewed X-inactivation
– She has an affected father and carrier mother (rare)
– Disorder is genetically heterogeneous (the condition may have non-X-linked recessive cause)
More physical symptoms from incontinentia pigment
Alopecia, hypodontia,
abnormal tooth shape,
and dystrophic nails are
observed
Male to male transmission is/is not observed in X-linked dominant diseases
is not
