Sex Ch/disorders of sexual development Flashcards
X ch. inactivation occurs when? (think developmentally)
During embryogenesis
Imprinting occurs when? (bonus)
During gametogenesis (before fertilization)
What type of X inactivation is seen in balanced and unbalanced autosomal translocation?
Nonrandom/preferential
Balanced autosomal trans:
-Inactivation of normal X
Unbalanced autosomal trans:
-Inactivation of abnormal X (derX)
XIST gene codes for what?
non coding RNA that binds to Barr Body complex
XIST function
allows for DNA methylation and histone modification in promoter regions (preventing genes from being transcribed)
Two types of ways X inactivation can occur when errors/mutation are present
Preferential/nonrandom inactivation:
- Non random inactivation
- Skewed X inactivation
Nonrandom inactivation occurs when?
occurs when balanced/unbalanced autosomal translocation occurs
What kind of inactivation occurs with balanced autosomal translocation
non random inactivation:
results in: normal X ch inactivation
What kind of inactivation occurs with unbalanced autosomal translocation
non random inactivation:
results in: abnormal X ch inactivation
Skewed x inactivation occurs when?
when female shows signs/symptoms of x linked recessive conditions.
(duchenne, fragile x, muscular dystrophy)
Skewed x inactivation results in what?
more normal x chromosomes are turned off
Prenatal cystic hygroma, puffy hands and feet, and coarctation of aorta observed in what aneuploidy disease?
Turners syndrome
Do individuals with Turners have normal intelligence or mild-severe intellectual disability?
Normal (remember video)
small testes, hypospadias, gynecomastia observed in what aneuploidy disease?
Kleinfelter’s syndrome 47, XXY
47 XYY
Phenotype?
Jacobs disease (Boys)
tall, learning disabilities, speech delays developmental delays, behavioral/emotional difficulties, autism spectrum
47 XXX,
phenotype?
Triple X syndrome (girls)
tall, kidney abnormalities, learning disabilities, speech delays, low motor milestones, seizures,
5 important txn factors/factors for male sex differentiation
SRY
SOX 9
Steroidogenic factor (SF1) - ch
NR5A1
FGF9 (fibroblast growth factor)
SRY (factor)
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
SOX9
-what ch is its gene found on
-function
what does it inhibit and what inhibits it?
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
Sertoli cells
- which week are they formed
- function
7th week
-production of anti-mullerian hormone (MIs), which causes regression of paramesophric duct (in 8th week)
Leydig cells
- which week are they formed
- function
7th week
-produce testosterone (in 8th week)
SF1/NR5A1
function
transcription factor that stimulates differentiation of sertoli/leydig cells
FGF9
function
chemototic growth factor that causes tubules from mesonephric duct to penetrate gonadal ridge
-essential for differentiation of testis
Important genes for female development
- WNT gene
- DHH gene
- RSPO1 gene
