Human Disorders due to CS Number

Question 1

Fragile. syndrome

Answer 1

alt to c/s

male mental diff.

Question 2

Diagnosis

Answer 2

analysis of karyotype
mosaic- cell to cell diff- less severs
Metaphase spread

Question 3

Metaphase spread

Answer 3

1) Amniotic or blood sample
2) arrest w chochicinte @ met, spind fibres stop
3) incubate hypotonic, spread out c/s
4) fix stain paint

Question 4

c/s classification

Answer 4

7 groups
A → G
44 autosomes
2 sex 
men are hemiygous due to XY

Question 5

C/s banding

Answer 5

stain centromere
p arms (short)
q arms (long)
p/q ratio gives name

Question 6

q/p=1

Answer 6

metacentric

Question 7

q/p= 1.5 -2.5

Answer 7

submetacentric

Question 8

q/p= 2.5-10

Answer 8

acrocentric

Question 9

q/p= n/a

Answer 9

telocentric (at the end)

Question 10

G bands

Answer 10

Giemsa

heterochromatin stains more than euchromatin

Question 11

R banda

Answer 11

Reverse

euchromatin stains more than heterochromatin

Question 12

FISH

Answer 12

fluorescent painting

Question 13

diploid

Answer 13

full complement

Question 14

haploid

Answer 14

half

Question 15

polyploid

Answer 15

more than normal
lethal in animal
normal in plants ie triploid

Question 16

aneuploid

Answer 16

less than complete set due to non-disjunction

Question 17

Down Syndrome

Answer 17

Mosaicism 1%
Trisomy 21

Mongoloid facial appearance
flat facial profile
epicanthal skin folds
low set ears
protruding tongue
low nose bridge
simian palmar crease
mental retardation
reduced life expectancy
>80 assoc physical disorders
60% congenital heart disease
susceptible to infection
predisposed to leukaemia
Poor skeletal development

Question 18

Patau Syndrome

Answer 18

Trisomy 13
47XX

1 in 20K live births
cleft lip or palate
defects in digit development (polydactyl)
eye defects
brain and CNS defect
Survival < 6mnth
1 cerebral ventricle rather than 2 cerebral hemisphere

Question 19

Klinefelters

Answer 19

XXY

1 in 2K births
normal life span and IQ
very tall leg bones
hypogonadism
infertile
feminine characteristics
gynocomastia, fat deposition
reduced facial hair
osteoporosis 
acne

Supermale Syndrome FALSE

Question 20

Turner Syndrome

Answer 20

Monosomy XO
only survival monosomy

1 in 5K female births 
short stature
webbed neck
shield shape chest
normal IQ
no barr bodies
rare lymphoma
sterile w no menses

Question 21

Superfemale?

Answer 21

47 XXX

• 1 in 1K live births
• healthy w extra barr bodies

48 XXXX

• mild learning difficulty
• female

49 XXXXX

• severe learning difficulty
• female

Question 22

Aneuploidy of sex c/s

Answer 22

non disjunction
less of a genetic balance disturbance
extra copies of X are inactivated as Barr bodies

Question 23

The lyon hypothesis

Answer 23

X inactivation in any female XX cell
occurs late blastocyte
random
chance of X is inactive/active
all normal females are sex c/s mosaics

Question 24

Barr observed buccal cells

Answer 24

dense stain at periphery of nucleus
barr bodies
only in female somatic cells

Question 25

Translocation

Answer 25

Robertsonian fusion of q arms in acrocentric c/s

causes 4% of Downs