Flashcards in Clinical genetics Deck (46):
the aetiology of disease rests on 3 conditions
deine multifactorial disorder
multiple genes (genetic predisposition) and environmental factor
define single gene disorder
a mutation in a single gene = Mendelian inheritance
define chromosomal disorder
an imbalance or rearrangement in chromosome structure eg aneuploidy, deletion, translocation
a mutation in mitochondrial DNA
define somatic mutation
mutation(s) within a gene(s) in a defined population of cells that results in disease
what are the 4 gene modes of inheritance
how many chromosomes do we have
do autosomal dominant conditions run from generation to generation.
Are males and females equally affected in autosomal dominant conditions
what % does offspring of an affected person have of inheriting the condition
what types of molecules do mutations of a autosomal dominate fashion affect.
structural proteins, receptors and transcriptional factors.
examples of conditions which are inherited in a autosomal dominant manner
Frequency of people with the genotype who express certain charcterisitics.
define full penetrance
mutation results in have the disease.
define incomplete penetrance
mutation is present but they may not have the disease.
variation in expression ( the extent to which a heritable trait is manifested by an individual)
symptoms more apparent at an earlier age as it is passed from one generation to the next.
define de novo mutations
new mutation that has occurred during gametogenesis or in early embryonic development.
Do autosomal recessive conditions pass from generation to generation
No- parents typically affected .
what types of relationship increase risk of recessive disorders.
do autosomal recessive conditions affect males and females equally
what % chance will the offspring of an affected person will get the condition
what % chance is there that a affected person will have a offspring who is a carrier
examples of autosomal recessive conditions
sickle cells disease
which gender is affected in X-linked conditions
(females can be mildly affected0
Can you have ale to male transmission of a X-linked condition
examples of X-linked conditions
duchenne's muscle dystrophy
fragile X syndrome
Red/green colur blindness
if the mother is a carrier of a X-linked condition then what are the chances that the male is affected.
If the mother is a carrier of a X-linked condition then what are the chances that the female is carrier
If the father is affected by a X-linked condition then how will this affect all daughter and son offspring
all daughters are carriers.
all sons are unaffected.
what are the 2 main factors which cause females to have such variable X-linked phenotypes
XL dominant vs XL recessive inheritance inheritance
X inactivation is aka
what happens in X-inactivation
The process of random inactivation of one of the X chromosomes in cells with more than one X chromosome.
Compensates for the presence of the double X gene dose.
what is the shut down X in lyonisation called
when does X inactivation take place
define skewed X-inactiavtion
random preference for “normal” X chromosome to be inactivated
define tissue variability (int terms of X inactivation)
random preference for the X chromosome with the mutation to be active in crucial tissue group
define X linked dominance
a dominant gene is only carried on the X chromosome (less common than recessive condition)
define X linked recessive
a recessive gene is only found on the X chromosome ( more common that dominant condition)
example of XL dominant
Fragile X syndrome
examples of XL recessive
Red-green colour blindness
Duchene Muscular dystrophy
is mitochondrial inheritance from the mother father or both.
All our mitochondria are inherited from our mother
how many genes have mitochondrial DNA
How will the children of a affected mother be affected
all have mutation