1a Disorders of Early Development

Question 1

What can cause pregnancy loss in humans?

Answer 1

• Errors in embryo-fetal development
• Failure of the embryo to implant in the uterine lining
• Inability to sustain development of the implanted embryo

Question 2

What is meant by a miscarriage?

Answer 2

Loss of pregnancy before 23 weeks gestation

Question 3

What is the definition of a early clinical pregnancy loss?

Answer 3

Loss before 12 weeks gestation

Question 4

What is meant by a late clinical pregnancy loss?

Answer 4

Loss of pregnancy after 24 weeks gestation

Question 5

What is meant by recurrent misscarriage?

Answer 5

In the UK, defined as three or more pregnancy losses

US: two or more pregnancy losses

Question 6

What is the major cause of early pregnancy loss?

Answer 6

Aneuploidy (chromosome number errors)

Question 7

How does the risk of trisomic pregnancy increase with materal age?

Answer 7

Exponential increase

Question 8

Why does aneuploidy increase with maternal age?

Answer 8

As the mother gets older, the cohesion proteins which hold the chromatids of homologous chromosomes together are degraded, leading to a loss of cohesion between the chromatids - results in the chromatids separating and drifting during mitotic division rather than being segregated accurately

Question 9

What is the name of two cohesion proteins involved in maintaining cohesion between chromatids within chromosomes?

Answer 9

REC8 and SMC2

Question 10

What proportion of conceptions are lost before the pregnancy is detectable by ultrasound scan?

Answer 10

50%

Question 11

What do embryos require to be viable?

Answer 11

Meternally and paternally derived genomes

Question 12

What happens when the spindle cannot grad a hold of the chromatids peoperly?

Answer 12

Leads to non-disjunction leading to aneuploidy

Question 13

What causes a complete molar pregnancy?

Answer 13

When an empty egg is fertilised by one or two sperm, resulting in all the genetic material from the father

Question 14

What is meant by a partial /incomplete molar pregnancy?

Answer 14

When a normal egg is fertilised by two sperm, so the embryo has three sets of chromosomes

Question 15

Which genome drives placental development?

Answer 15

Paternal genome

Question 16

Which genes are only expressed from the paternally inherited copy?

Answer 16

genes which promote the embryos fitness to survive at the expense of the mother

Question 17

Which genes are only expressed from the maternally inherited copy?

Answer 17

Genes which restrict embryo fitness to conserve resources for future pregnancies

Question 18

What happens genetically when there is a molar pregnancy?

Answer 18

There is a genetic imbalance - eg if more paternal genes are expressed, there will be less of a balance and placenta will be enlarged

Question 19

Why do complete molar pregnancies result in enlarged placentas?

Answer 19

There is a genomic imbalance, meaning more paternally-inherited genes are expressed, leading to a lot of placental development

Question 20

What are gestational trophoblastic diseases?

Answer 20

A collection of disorders characterized by overgrowth of trophoblastic tissue

Question 21

What is the difference between a complete and partial hydatidiform mole?

Answer 21

in a complete hydatidiform mole, there is no fetal tissue, but there is fetal tissue in a partial one

Question 22

What is an example of a benign gestational trophoblastic disease?

Answer 22

Hydatidiform mole

Question 23

What forms when the gestational trophoblastic disease becomes malignant?

Answer 23

Forms a gestational trophoblastic neoplasia

Question 24

What are rare examples of malignant gestational trophoblastic neoplasias?

Answer 24

Invasive moles, Choriocarcinoma

Question 25

What are very rare examples of malignant gestational trophoblastic neoplasias?

Answer 25

Placental site trophoblastic tumour, epithelioid trophoblastic tumour

Question 26

What is meant by an ectopic pregnancy?

Answer 26

When the embryo implants at a site other than the uterine endometrium

Question 27

Where do the majority of ectopic pregnancies occur?

Answer 27

In the fallopian tubes

Question 28

What can occur if the ectopic pregnancy ruptures?

Answer 28

Severe internal bleeding

Question 29

What chemical in cigarette smoke regulates the expression of PROKR1?

Answer 29

Cotinine

Question 30

What does PROKR1 do?

Answer 30

regulates fallopian tube smooth muscle contractility

Question 31

What does cotinine induce in fallopian tube explants?

Answer 31

Pop-apoptosis protein expression

Question 32

Why does smoking reduce tubal transit of the embryo?

Answer 32

tobacco smoke inhibits cilia function

Question 33

What factors increase the risk for ectopic pregnancy?

Answer 33

Prior ectopic pregnancy or fallopian tube surgery, STIs, pelvic inflammatory disease, endometriosis

Question 34

What is endometriosis

Answer 34

When parts of the endometrium start growing in other places like the

Question 34

What is endometriosis

Answer 34

When parts of the endometrium start growing in other places like the

Question 35

What may underpin recurrent miscarriage/pregnancy loss?

Answer 35

Disruptions of local signalling pathways controlling implantation