Sex Ch/disorders of sexual development

Question 1

X ch. inactivation occurs when? (think developmentally)

Answer 1

During embryogenesis

Question 2

Imprinting occurs when? (bonus)

Answer 2

During gametogenesis (before fertilization)

Question 3

What type of X inactivation is seen in balanced and unbalanced autosomal translocation?

Answer 3

Nonrandom/preferential

Balanced autosomal trans:
-Inactivation of normal X

Unbalanced autosomal trans:
-Inactivation of abnormal X (derX)

Question 4

XIST gene codes for what?

Answer 4

non coding RNA that binds to Barr Body complex

Question 5

XIST function

Answer 5

allows for DNA methylation and histone modification in promoter regions (preventing genes from being transcribed)

Question 6

Two types of ways X inactivation can occur when errors/mutation are present

Answer 6

Preferential/nonrandom inactivation:

1. Non random inactivation
2. Skewed X inactivation

Question 7

Nonrandom inactivation occurs when?

Answer 7

occurs when balanced/unbalanced autosomal translocation occurs

Question 8

What kind of inactivation occurs with balanced autosomal translocation

Answer 8

non random inactivation:

results in: normal X ch inactivation

Question 9

What kind of inactivation occurs with unbalanced autosomal translocation

Answer 9

non random inactivation:

results in: abnormal X ch inactivation

Question 10

Skewed x inactivation occurs when?

Answer 10

when female shows signs/symptoms of x linked recessive conditions.
(duchenne, fragile x, muscular dystrophy)

Question 11

Skewed x inactivation results in what?

Answer 11

more normal x chromosomes are turned off

Question 12

Prenatal cystic hygroma, puffy hands and feet, and coarctation of aorta observed in what aneuploidy disease?

Answer 12

Turners syndrome

Question 13

Do individuals with Turners have normal intelligence or mild-severe intellectual disability?

Answer 13

Normal (remember video)

Question 14

small testes, hypospadias, gynecomastia observed in what aneuploidy disease?

Answer 14

Kleinfelter’s syndrome 47, XXY

Question 15

47 XYY

Phenotype?

Answer 15

Jacobs disease (Boys)

tall,
learning disabilities,
speech delays
developmental delays,
behavioral/emotional difficulties,
autism spectrum

Question 16

47 XXX,

phenotype?

Answer 16

Triple X syndrome (girls)

tall,
kidney abnormalities,
learning disabilities,
speech delays,
low motor milestones,
seizures,

Question 17

5 important txn factors/factors for male sex differentiation

Answer 17

SRY
SOX 9
Steroidogenic factor (SF1) - ch
NR5A1

FGF9 (fibroblast growth factor)

Question 18

SRY (factor)

Answer 18

txn factor that initiates series of events -> development of testes

together with SOX9:

• induce differentiation of sertoli cells
  
  • > -production of anti-mullerian hormone (MIs), which causes regression of paramesophric duct

Question 19

SOX9
-what ch is its gene found on
-function
what does it inhibit and what inhibits it?

Answer 19

ch 17

together with SRY:

• induce differention of sertoli/leydig cells
  
  • > -production of anti-mullerian hormone (MIs), which causes regression of paramesophric duct
• inhibits WNT4
• inhibited by DHH

Question 20

Sertoli cells

• which week are they formed
• function

Answer 20

7th week

-production of anti-mullerian hormone (MIs), which causes regression of paramesophric duct (in 8th week)

Question 21

Leydig cells

• which week are they formed
• function

Answer 21

7th week

-produce testosterone (in 8th week)

Question 22

SF1/NR5A1

function

Answer 22

transcription factor that stimulates differentiation of sertoli/leydig cells

Question 23

FGF9

function

Answer 23

chemototic growth factor that causes tubules from mesonephric duct to penetrate gonadal ridge

-essential for differentiation of testis

Question 24

Important genes for female development

Answer 24

1. WNT gene
2. DHH gene
3. RSPO1 gene

Question 25

What is the WNT4 inhibited by?

Answer 25

SOX9

Question 26

WNT4 protein

Answer 26

extracellular signaling factor responsible for differentiation of ovary

• inhibited by sox9
• co-activated by RSPO1
• upregulatessss DHH

Question 27

DHH

Answer 27

a nuclear hormon receptor

• upregulated by WNT4
• downregulatesssss SOX9

Question 28

RSPO1 gene

Answer 28

coactivator of WNT pathway