Genetic Disorders Flashcards
Autosomal recessive disorder examples
cystic fibrosis
anaemia / thalassaemias
dentinogenesis imperfecta
what gene is effected in cystic fibrosis
the CFTR gene
cystic fibrosis transmembrane conductance regulator gene
what is the function of CFTR
export cl- ions into the epithelial cells of the airways
what is the effect of genetic mutation on CFTR
build up of sticky mucous
what causes sickle cell anaemia and thalassaemias
- single base mutation in haemoglobin
how does selective pressure of endemic malaria, link with thalassaemieas
higher frequency of thalassaemias- balanced polymorphism.
the mutation in haemoglobin gives a selective advantage
what is the effect of dentinogenesis imperfecta
early tooth loss
what common genetic mutation causes dentinogenesis imperfecta
C to T substitution in DSPP gene
what does the DSPP gene affected in dentiogensis imperfecta stand for
Dentin sialo-phospho-protein
what chromosome is DSPP located
chromosome 4
give an example of an autosomal domininant disease
Huntington’s disease- depression, dementia, spasms
if one parent has mutated allele, what is the risk of offspring having Huntington’s disease
50%
what is the molecular basis of Huntington’s disease
increase in the number of repeats CAG
- normal= 15 copies of repeat sequence
- affected= 36+ copies
what is X-linked inheritance
females are carriers
only males affected
carried on X thus no evidence of father-son transmission
give examples of x-linked disorders
Haemophillia (blood clotting factors are affected)
amelogensis imperfecta (poorly formed tooth enamel)
amelogensis imperfecta is a multi- factoral genetic disease. what does this mean
many genes involved in disease process
severity is affected by genes and environmental conditions
what are some common genetic disorders with multi- factoral genetic component
congenital: spina bifida, cleft lip and palate, congenital heart disease
late onset: rheumatoid arthritis, MS, diabetes mellitus, epilepsy
psychiatric: manic depression, alcoholism, alzheimer’s disease, schizophrenia
what are some common genetic disorders with environmental component
neoplasias: oral cancer, breast cancer, congenital heart disease
cardiovascular diseases: hypertension, MS, epilepsy
neurodegenerative: diabetes, alcoholism, alzheimers disease
what is seen with patients who have amelogensis imperfecta
stripes of affected enamel
in females= mosaic expression of disease due to X-inactivation
what gene is mutated in amelogensis imperfecta
the tooth enamel matrix protein, amelogenin, AMELX
periodontal disease is multifactoral. which factors affect its severity?
disease initiating factors (dental plaque/ oral hygiene)= individual genetic response which determines the severity
