Genetic Mechanisms in Diseases II

Question 1

example of somatic mosaicism that presents with localized distribution of benign tumors

Answer 1

Segmental Neurofibromatosis

Question 2

example of somatic mosaicism that has activation of GNAS1 gene leading to increased cAMP

presents with triad of presentations:
fibrous dysplasia
early puberty
cafe au lait

Answer 2

McCune Albright Syndrome

Question 3

same disease caused by mutations on different genes

Answer 3

locus heterogeneity

Question 4

example of locus heterogeneity that presents with ophthalamic triad:
1. mottled appearance of retinal pigment epithelium
2. waxy optic nerve
3. attenuation of blood vessels in retina

Answer 4

retinitis pigmentosa

Question 5

example of locus heterogeneity that deals with OCA1 deficiency; deals with tyrosinase deficiency

reduced visual acuity; pallor

Answer 5

oculocutaneous albinism

Question 6

example of locus heterogeneity that deals with LDL receptor mutations and causes skin xanthomas (lesions on skin containing cholesterol and fat)

Answer 6

Familial hypercholesteremia

Question 7

this disease is autosomal dominant and displays incomplete dominance

sx’s:
tendon xanthomas
arcus corneae (white or blue ring around cornea
atherosclerosis

Answer 7

familial hypercholesterolemia

Question 8

same gene, different mutations

Answer 8

allelic heterogeneity

Question 9

example of allelic heterogeneity that deals with reduction of synthesis of globin beta chain

Answer 9

Beta-thalassemia

Question 10

presents severe anemia, iron overload

Answer 10

Beta-thalassemia

Question 11

example of ex vivo gene therapy

Answer 11

beta-thalassemia

Question 12

example of in vivo gene therapy

Answer 12

retinal dystrophy

Question 13

the net effect of this is only one allele is expressed and the other is inactivated

Answer 13

genomic imprinting

Question 14

father passes down mutant allele to son, but if it’s imprinted, will it be expressed or inactivated?

Answer 14

inactivated

Question 15

this syndrome is due to genomic imprinting and causes paternal deletion on chromosome 15 (not inherited)

Answer 15

Prader-Willi Syndrome

Question 16

sx’s of this genomic imprinting disorder:
short stature
excessive eating

Answer 16

Prader-Willi Syndrome

Question 17

this syndrome is due to genomic imprinting and causes maternal deletion on chromosome 15 (not inherited)

Answer 17

Angelman syndrome

Question 18

sx’s of this genomic imprinting disorder:
inappropriate laughter
seizure, speech delay

Answer 18

Angelman syndrome

Question 19

a person receives 2 copies of chromosome from one parent and zero copies from the other

Answer 19

uniparental disomy