genetic disorders Flashcards
huntingtons
it is an autosomal dominant disease that affects the brain cells –> causes cell death in the brain
huntington’s disease causes too many repetitions of CAG, more than or equal to 40 repetions
cystic fibrosis
autosomal recessive disease in the lungs
a defect in the gene (= cystic fibrosis transmembrane conductance regulator CFTR)
–> affects chloride ions
diseased individuals will either lack or have defective gene and then cause sticky and thick mucus
(chloride ions usually causes entry of water, with no chloride ions, the mucus is not diluted and gets extra sticky)
sickle cell disease
autosomal recessive disorder
mutation in the HBB gene which produces haemoglobin S (HbS) instead (HbA)
heterozygous individuals show sickle cell trait
half of haemoglobin is normal
incomplete dominance phenotype
sickle shaped cells
sex chromosomes
present in somatic cells
males have one X and one Y
females have two X
x-linked dominant
affected females X^H X^H or X^H X^h (homo or heterozygous)
affected males X^H Y (hemizygous, definitely gonna get affected, one allele is sufficient to cause the disease)
x-linked recessive
affected females X^h X^h
affected males X^h Y hemizygous
mostly likely to occur
rare to have homozygous recessive, females usually just carriers X^H X^h
y-linked
abnormal allele only passed on from father to son
haemophilia general
x-linked recessive disorder
clotting deficiency
mutation genes in the protein that code for the coagulators, can’t properly blood clot
haemophilia A
deficiency of clotting factor VIII
haemophilia B
deficiency of clotting factor IX
red green colour blindess
x-linked recessive disorder
mutations in the OPN1LW or OPN1MW gene which makes abnormal opsin pigments in cone cells of retina
opsin pigments are affected, reduced senstivity to green
can’t distinguish green, red and yellow
pedigrees
filled sqaure : affected male
empty sqaure : normal male
filled circle : affected female
empty circle : normal female
