4. Karyotyping Flashcards
Citrullinaenemia
Molecular origin:
- single base pair substitution (CGA –> TGA(stop)) (1st position of 86th triplet)
- deficient in enzyme argininosuccinate synthase (ASS)
- Leads to a buildup of ammonia and citrulline
inheritance:
-no dominance (recessive) for ASS activity
recessive disease
symptoms:
- normal calves at birth with signs of depression within hours
- protruding tongue and unsteady gait after 1 day
- death after 3-5 days
overo lethal white syndrome
horses
pure white foals
inheritance:
- homozygous =death
- frame overo patterned parents
Molecular origin:
-single amino acid sub (118 on endothelin-B receptor gene)
Symptoms:
-underdeveloped and contracted intestines
congenital deafness
mode of inheritance
-dominant white gene in cats with blue eyes (usually long-haired)
Symptoms:
-deafness (unilateral or bilateral deafness)
-degeneration of cochlear blood supply after 3-4 weeks
inheritance not understood
grey collie syndrome
canine cyclic neutropenia
symptoms:
- light coat, light nose
- small puppies show signs after 8-12 weeks
- die within 12 months
- stem cell disorder
Mode of inheritance
- immunodeficiency (inherited)
- autosomal recessive
Henny feathering
mode of inheritance:
- sex-limited
- autosomal gene
- no dominance in aromatase activity
- complete dominance in henny feathering
symptoms/ molecular component:
- -hens are normal
- if expressed in males aromatase enzyme produces estrogen and results in cocks looking like females and are demasculinized
- reduces reproduction ability of males due to high estrogen
Phenocopy
phenotype of single-gene disorder due to E
normal genotype
a-mannosidosis
lysosomal storage disease
grazing on legume Darling-Pea inhibits the same enzyme as the genetic disorder
MHS
pigs
threshold disorder
happens when subjected to mild stress
symptoms:
- increase in body temp
- metabolic and respiratory acidosis
- death
inheritance:
- homozygous mis-sense mutation in gene for calcium-release
- single gene
- autosomal recessive
- incomplete penetrance
checking for heritability of disorders
Criteria
- Is the defect present in more than one season with different E
- does the pedigree records show a specific lineage show more frequency for the defect
- does the inbreeding frequency suggest the expression of recessive genes
- use DNA testing to check for genetic defects
what actions can be taken against defects
establish the cause (E or G)
gene frequency: high or low incidence
is the defect of economic importance
is there an implication for seed stock breeders
eliminate the animals with defects
define a Karyotype
a set of all chromosomes that exist in a particular cell
list 6 Characteristics of karyotypes
absolute size
relevant size of chromosomes
position of the centromeres
basic number of chromosomes
number and positions of satellites
degree and distribution of heterochromatic regions
what do the bands in G- banding show
light bands:
-GC rich areas
dark bands:
-AT rich areas
What is used to stain in Q-banding
Quinacrine (fluoresencet pattern becomes visible)
explain C-Banding
Giemsa binds to constitutive heterochroma
stains centromeres
