Embryology and Genetics Flashcards
where does the male duct system originate from
mesonephric
where does the female duct system originate from
paramesonephric
what controls the descent of the testes to the scrotum
gubernaculum
what else does gubernaculum help the descent of and where does it pull it to
the ovaries
they are pulled into a peritoneal fold
what stage does external genitalia have before male/female differentiation
indifferent stage
what contributes to the urinary, reproductive AND GI systems
the cloaca
what happens in the 3rd week in relation to development of the external genitalia
cloacal folds form fusing cranially to form genital tubercle
what happens in the 6th week in relation to development of the external genitalia
cloacal membrane divided into urogenital and anal membranes:
cloacal folds also divide into urethral and anal folds
what do the genital swellings form
scrotum (males) or labia major (females)
what is a possible abnormality between the urogenital system and hindgut and why can this happen
fistulae between urogenital system and rectum/anal canal
common origin
from what gestation week can amniocentesis be done
16+ weeks
from what gestation week can chorionic villus biopsy be done
11.5 weeks
from what gestation week can fetal blood sampling be done
18+ weeks
from what gestation week can fetal DNA be acquired from maternal blood
8+ weeks
what is the definition of a mutation
genetic change that causes disease
what is the definition of a polymorphism
Genetic Variation that is not per-se disease causing
what current prenatal screening in Scotland
Dating Ultrasound Scan with serum biochemistry – around 12 weeks
Serum Screening at around 16 weeks - maternal blood test to look for biochem markers of Down Syndrome
20 week detailed scan - looks for other fetal abnormalities
what is the genetic name for Down Syndrome
Trisomy 21
what are the best tests for Ix for Down Syndrome
Amniocentesis
array CGH [aCGH]
- 18 week gestation
what can aCGH detect
small deletions such as 22q11 deletion
what the definition of a balanced chromosome rearrangement
all the chromosomal material is present
what the definition of a unbalanced chromosome rearrangement
Extra or missing chromosomal material. Usually 1 or 3 copies of some of the genome.
what is the definition of Robertsonian translocation
Two acrocentric chromomosomes stuck end to end
ultrasound scanning - booking, detailed, cardiac anomalies, microcephaly, short limbs
Booking Scan - 10-12 weeks Detailed Scan - 20 weeks Cardiac - 12-20 weeks Microcephaly - after 22 weeks Short limbs - after 22 weeks
what genetic inheritance is DMD
x-linked recessive
What is risk that a child is affected with DMD if the mother is a carrier
1 in 4
[1 in 2 if you know its a boy]
what is the risk of a child acquired an autosomal recessive trait
1 in 4
what is the risk of a child acquired an autosomal dominant trait
1 in 2
when can a Chorionic Villus Biopsy be done
@ 11.5 + weeks
when can an Amniocentesis be done
@ 16 weeks
what is the embryo called on day 4 of development
morula
what is the embryo called on day 5 of development
blastocyst
