genetics Flashcards
what is penetrance
the likelihood of having a disease if you have a gene mutation
what are mendelian disorders
a disease that is predominantly caused by a change in a single gene
are mendelian disorders high or low penetrance
high penetrance
autosomal dominant inheritance
one copy of the faulty allele is sufficient to cause the disease
what is the chance of an affected person passing on the pathogenic variant to a child in autosomal dominance
50%
who is more likely to be affected by autosomal dominant disorders
males and females are equally likely to be affected
autosomal recessive inheritance
affected person has 2 faulty alleles
what makes autosomal recessive inheritance more likely
consanguineous parents
risk of a child being affected by an autosomal recessive disorder
25%
risk of a child being a carrier of an autosomal recessive disorder
50%
x-linked inheritance
the pathogenic variant is found on the x chromosome
differences in gender in x-linked inheritance with one pathogenic allele
females don’t show major clinical features
males with a single faulty allele will be fully affected
outcomes for children of a female carrier of x-linked disorder
25%
- unaffected daughter
- carrier daughter
- unaffected son
- affected son
outcomes for children of a male carrier of x-linked disorder
all daughters will be carriers and all sons will be affected
what causes females to not be so affected by x-linked inheritance
x-inactivation
what are the 3 main types of chromosomes
submetacentric
metacentric
acrocentric
how do sister chromatids attach
at the centromere
describe a metacentric chromosome
telomere is close to the middle, with a shorter p arm and a longer q arm
describe an acrocentric chromosome
centromere at one end, with only satellite DNA on the short p arm
during what phase of the cell cycle are chromosomes visible
during metaphase in mitosis
what is aneuploidy
there is a whole extra or missing chromosome
what is translocation
rearrangement of chromosomes
chromosomal abnormality in down syndrome
47XY +21
chromosomal abnormality in edwards syndrome
47 XY +18
