Principles of Genetic Disease Flashcards
Hereditary factor that determines a particular trait. Found on a specific region on a chromosome:
Gene
A variety of a gene (i.e. homozygous or heterozygous)
Allele
A structure made up of proteins and DNA and organized into genes
chromosomes
The genetic makeup of an indiviual consisting of the genes on all 46 chromosomes
genotype
observable characteristics or traits of an individual resulting from the genotype:
phenotype
One variant of a gene on a chromosome overrides the effect of a different variant of the same:
autosomal dominant
Two copies of an abnormal gene must be present for the disease or trait to develop
autosomal recessive
Structure of DNA:
double helix
DNA winds around ____ to form ____
histones; core particles
____ folds into a thicker zigzag fiber
chromatin
In dividing cells ___ forms into thick ____ visible to light microscope
chromatin; chromatids
Midpoint of cell division:
metaphase
Core particle=
nucleosome
Sister chromatids are connected by:
kinetochore
Shot arm =
p
long arm =
q
An individuals complete set of chromosomes:
karyotype
In a karyotype, chromosomes are arranged according to:
size and banding patterns
Same version of a gene is inherited from each parent
homozygous
different versions of a gene inherited from each parent
heterozygous
Single set of chromosomes in an organism
haploid
Two copies of each chromosome
diploid
genetic disease of familial inheritance, transmitted through generations
hereditary disorders
genetic disease present at birth:
congenital disorder
result from mutations in single genes:
mendelian disorders
Involve multiple genes, also including environmental influence
complex disorders
Change in # or structure of chromosomes
chromosomal abnormalities
Single gene hereditary mutation:
mendelian disorder
The three patterns of inheritance of mendelian disorders include:
- autosomal dominant
- autosomal recessive
- x-linked
Mendelian disorders are associated with a ___ of phenotypic effects
wide range
In mendelian disorders, the mutated gene can be influenced by:
modifier genes
In this type of inheritance, usually one parent is affected, and it is NOT sex dependent
autosomal dominant inheritance
Autosomal dominant inheritance may also occur due to new mutations within:
the sperm or egg
In Autosomal dominant inheritance, clinical features are modified by:
reduced penetrance and variable expressivity
in Autosomal dominant inheritance, the age of onset may be delayed from childhood, such as in:
Huntington disease
____ inheritance is manifested in the homozygous state
autosomal recessive
In autosomal recessive inheritance to occur, how many parents must be carriers?
both
Autosomal recessive inheritance onset:
usually early in life
Complete penetrance is common with ___ type of inheritence
autosomal recessive
With what type of inheritance are new mutations rarely detected clinically?
autosomal recessive
One copy of the x-chromosome is inactivated
lyonization
Inactivated x-chromosome observed in nucleus
barr body
The process of lyonization is considered:
random
Almost all sex-linked disorders are:
x-linked
Most x-linked disorders are:
recessive
Female carriers transmit only to sons (50%)
recessive transmission
Affected males do not transmit disorders to sons but all daughters are carriers:
x-linked disorder
Familial hypercholesterolemia has an AD prevalence of:
1/500
Disease characterized by loss of function mutations in gene encoding LDL receptor:
familial hypercholesterolemia
LDL receptor is involved in:
transport and metabolism in cholesterol
Familial hypercholesterolemia results in elevated levels of _____ —-> _____ —-> ____
cholesterol; premature atherosclerosis; MI risk
Clinical feature of familial hypercholesterolemia involving the skin:
skin xanthomas