Genetic Disorders

Question 1

Autosomal recessive disorder examples

Answer 1

cystic fibrosis
anaemia / thalassaemias
dentinogenesis imperfecta

Question 2

what gene is effected in cystic fibrosis

Answer 2

the CFTR gene

cystic fibrosis transmembrane conductance regulator gene

Question 3

what is the function of CFTR

Answer 3

export cl- ions into the epithelial cells of the airways

Question 4

what is the effect of genetic mutation on CFTR

Answer 4

build up of sticky mucous

Question 5

what causes sickle cell anaemia and thalassaemias

Answer 5

1. single base mutation in haemoglobin

Question 6

how does selective pressure of endemic malaria, link with thalassaemieas

Answer 6

higher frequency of thalassaemias- balanced polymorphism.

the mutation in haemoglobin gives a selective advantage

Question 7

what is the effect of dentinogenesis imperfecta

Answer 7

early tooth loss

Question 8

what common genetic mutation causes dentinogenesis imperfecta

Answer 8

C to T substitution in DSPP gene

Question 9

what does the DSPP gene affected in dentiogensis imperfecta stand for

Answer 9

Dentin sialo-phospho-protein

Question 10

what chromosome is DSPP located

Answer 10

chromosome 4

Question 11

give an example of an autosomal domininant disease

Answer 11

Huntington’s disease- depression, dementia, spasms

Question 12

if one parent has mutated allele, what is the risk of offspring having Huntington’s disease

Answer 12

50%

Question 13

what is the molecular basis of Huntington’s disease

Answer 13

increase in the number of repeats CAG

• normal= 15 copies of repeat sequence
• affected= 36+ copies

Question 14

what is X-linked inheritance

Answer 14

females are carriers
only males affected
carried on X thus no evidence of father-son transmission

Question 15

give examples of x-linked disorders

Answer 15

Haemophillia (blood clotting factors are affected)

amelogensis imperfecta (poorly formed tooth enamel)

Question 16

amelogensis imperfecta is a multi- factoral genetic disease. what does this mean

Answer 16

many genes involved in disease process

severity is affected by genes and environmental conditions

Question 17

what are some common genetic disorders with multi- factoral genetic component

Answer 17

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

Question 18

what are some common genetic disorders with environmental component

Answer 18

neoplasias: oral cancer, breast cancer, congenital heart disease

cardiovascular diseases: hypertension, MS, epilepsy

neurodegenerative: diabetes, alcoholism, alzheimers disease

Question 19

what is seen with patients who have amelogensis imperfecta

Answer 19

stripes of affected enamel

in females= mosaic expression of disease due to X-inactivation

Question 20

what gene is mutated in amelogensis imperfecta

Answer 20

the tooth enamel matrix protein, amelogenin, AMELX

Question 21

periodontal disease is multifactoral. which factors affect its severity?

Answer 21

disease initiating factors (dental plaque/ oral hygiene)= individual genetic response which determines the severity