Genetic Diseases 2

Question 1

Foxglove purple/white petals

Answer 1

2 loci involved, hmz at either = white; htz at both=purple

Complementation
-> 2 different hmz recessive mutations produce same phenotype

Question 2

Human Deafness

Answer 2

Many loci affect hearing pathway - from outer ear to aud nerve and brain

Complementation

Question 3

Colour Blindness

Answer 3

X-linked - (daltonism)

Question 4

Lesch-Nyhan syndrome

Answer 4

Error in purine metabolism - self-mutilation, death

X-linked

Question 5

Haemophilia

Answer 5

Factor VIII deficiency - blood can’t clot properly

X-linked
mutation probably happened in Queen Victoria’s father - who was old

Question 6

Duchenne muscular dystrophy (DMD)

Answer 6

Detect age 3-5, fatal in 20s

X-linked/ X-chromosome inactivation
one remarkable case of MZtwins, each had inactivated a different X chromosome, 1 had DMD, 1 did not

Question 7

Tortoiseshell cat

Answer 7

Patches of black and orange fur (black activ 1 X chr, orange the other)

X chr inactivation, XCI

Question 8

Colourblindness in women

Answer 8

woman htz: some retinal cells normal, some colour-blind

X chr inactivation, XCI

htz woman can see even though some retinal cells are abnormal

Question 9

Patau syndrome

Answer 9

Trisomy 13

chromosomal abnormality

Question 10

Notch Wing

Answer 10

in Drosophila melanogaster

- chr deletion

Question 11

Cri-du-chat

Answer 11

lose tip of chr 5

• chr deletion
• child voice sounds like cat

Question 12

Globin, odorant-receptor gene families

Answer 12

chr duplication

increase genetic material progressively, then changes, get new but similar genes : families

Question 13

Dm Bar eye

Answer 13

Bigger eye
- chr duplication
if cross 2 Bar eye: sometimes get double Bar eye + normal eye – due to slippage

Question 14

Myeloid leukemia

Answer 14

Translocation 5-11/ 9-22

• > myeloid line of blood
• > abnormal WBC in bone marrow

Question 15

Burkitt’s lymphoma

Answer 15

Translocation 8-14

-> B cells + impaired immunity

Question 16

Down’s syndrome

Answer 16

trisomy 21 / translocation 14-21

Aneuploidy
early aging, excess water in uterus - flat face, fingerprints

Question 17

Edward’s syndrome

Answer 17

trisomy 18

Aneuploidy
lethal - kidney, heart abnorm (sth w clenched fingers)

Question 18

Klinefelter’s syndrome

Answer 18

XXY, XYY male // XXX female

Aneuploidy
XXY is male but has some female characteristics - sometimes dont notice till fertility tests

Question 19

Turner’s syndrome

Answer 19

XO, female

Aneuploidy
If females normally have 1 inactivated, should be normal, right ?NO - heart stuff, diabetes,

Question 20

Gynandromorphs

Answer 20

Half male half female - mosaic (due to error in mitosis in early dvp)

Somatic Aneuploidy
Dm one red eye one white

Question 21

Modern wheat

Answer 21

is hexaploid

Allopolyploid
-triticale is another allopolyploid

Question 22

banana, ginger, seedless melon

Answer 22

infertile triploids

¿? autopolyploid (modern manipulation)

Question 23

Siamese cats

Answer 23

Fur colour det by mut in melanin gene - enzyme doesnt work at high temp

Temperature-sensitive mutations
-cooler parts of body ie ears/paws are dark cause cooler temp in extremities

Question 24

White-blood in Dm

Answer 24

high temp light eyes/low temp dark eyes

Temperature-sensitive mutations
-use to study temp-sensitive period of dvp

• correlated w/ mutation in eye cryptochrome gene
• gene-env interaction

Question 25

phenylketonuria, PKU

Answer 25

absent Phenylalanine hydroxylase, PAH

• gene-env interaction, chemical
• recessive
• can’t break down Phe -> special diet

Question 26

porphyria variegata

Answer 26

Defict in some enzyme - cant break down porphyin component of haemoglobin, it accumulates (light sensitive chemical)

• gene-env interaction, chemical
• inc pen __rec/dom
• neurolog sympt, light sensitivity, low doses of barbiturates lethal - maybe gave origin to werewolf legend // George III

Question 27

factor V leiden thrombophilia

Answer 27

Disorder of blood clotting
incomplete penetrance, gene-env interaction, chemical
- dominant

Question 28

Baldness

Answer 28

gene-env interaction, sex limitation

- dominant