Week 2- Sexual Determination

Question 1

What fetal defects might be seen with the following?

• Maternal DM
• Rh disease
• SLE
• APA
• Early amniocentesis
• CVS
• ACEi/ ARBs

Question 2

Trisomic vs. monosomic rescue

Heterodisomy vs. isodisomy

Prader-Willi (paternal deletion of maternal UPD)

Angelman’s opposite

Question 3

Prenatal screening

Answer 3

Quad

SIPS (= Quad + PAPP-A)

IPS= SIPS + NT

Amnio done @ >15 wks

CVS done at 10-12 wks

Question 4

Sertoli make MIS which causes Mullerian atrophy

Leydig make TT which maintains wolffian structures (vas, epididymis, seminal vesicles)

TT–> DHT required to zip up external genitalia

Question 5

What are Wolffian and Mullerian structure remnants

Answer 5

Wolffian: epoophoran, gartner cyst

Mullerian: appendx testis, utriculus prostaticus

Question 6

Timing of sexual differentiation

Answer 6

6 weeks: primordial germ cells migrate

7 weeks: testes form

10-11 weeks : ovarian determination… external genitalia is indifferent until then too.

12 weeks uterus fusion

14 weeks penile fusion

Question 7

Phenotypes of disorders

Answer 7

Complete androgen insensiivity: unambiguous female

CAH: XX is more likely to come to attention…virilized female, but normal female internal gentalia because this is formed by the time that adrenal stuff kicks in.

Mixed gonadal dysgenesis : 45X/46XY…phenotype depends on which tissue get the XY

Turners: usually get streak ovaries…both XX required to maintain ovaries

Question 8

3-5% of live births have major anomaly at birth

14% have single minor anomaly

Question 9

Examples of malformation vs. disruption vs. deformation

Answer 9

malformation:

• syndactyly
• spina bifida
• cleft palate
• congenital heart lesions

Disruptions

• amniotic band disruption
• porencephaly

deformation

• e.g oligohydramnios sequence