PRENATAL DIAGNOSIS

Question 1

INTRINSIC abnormality “programmed” in development

Answer 1

MALFORMATION

Spina bifida
Omphalocele

Question 2

Fetus develops abnormally because of EXTRINSIC MECHANICAL FORCES imposed by uterine environment

Answer 2

DEFORMATION

Limb contractures that develop w/ oligohydramnios from bilateral renal agenesis

Question 3

More severe change in form or function that occurs when genetically normal tissue is modified as a result of a specific insult

Answer 3

DISRUPTION

damage from an amniotic band –> limb reduction defect

Question 4

Cluster of several anomalies or defects that have the same cause

Answer 4

SYNDROME

Trisomy 18

Question 5

Anomalies that all developed sequentially from one initial insult

Answer 5

SEQUENCE

Pierre-Robin Sequence - micrognathia, glossoptosis

Question 6

Group of specific abnormalities that occur frequently but do not seem to be linked etiologically

Answer 6

ASSOCIATION

VACTERL association - > 3 of the ff
Vertebral defects
Anal atresia
Cardiac defects
TracheoEsophageal fistula
Renal anomalies
Limb abnormalities

Question 7

Inherited from 1 parent w/ the disease via a SINGLE GENE DEFECT

Answer 7

Autosomal Dominant

Question 8

Required 2 affected alleles

Answer 8

Autosomal Recessive

Question 9

Carried by MOTHER who is UNAFFECTED and passed only to SONS

Answer 9

X-linked disorders (hemophilia, fragile X)

Question 10

Mothers –> sons and daughters

Fathers –> daughters

Answer 10

X-linked dominant

Aicardi syndrome - LETHAL in MALE

Question 11

Presence of one or more extra chromosomes –> trisomy, or loss of chromosome monosomy

Answer 11

ANEUPLOIDY

> 50% of 1st trimester abortions

Question 12

1st Trimester Aneuploidy Screening

11 and 14 weeks of gestation

Answer 12

human chorionic gonadotropin (hCG)
pregnancy associated plasma protein A (PAPP-A)
sonographic measurement of the nuchal translucency (NT)

DOWN SYNDROME
HIGHER b-hCG and LOWER PAPP-A

Question 13

Increased nuchal translucency (NT) is associated with

Answer 13

various birth defects - FETAL CARDIAC ANOMALIES

Question 14

2nd Trimester Aneuploidy Screening

15 - 21 weeks of gestation

Answer 14

DOWN SYNDROME
DECREASED - maternal serum AFP and unconjugated estriol
INCREASED hCG and dimeric inhibin levels

TRISOMY 18
DECREASED - maternal serum AFP, unconjugated estriol, hCG

Question 15

QUAD SCREEN TEST

Answer 15

1. alpha fetoprotein (AFP)
2. beta human chorionic gonadotropin (b-hCG)
3. unconjugated estriol
4. dimeric inhibin A (DIA)

Question 16

Maternal Serum Estriol Level

Answer 16

DECREASED
Smith Lemli Opitz Syndrome
Steroid Sulfatase Deficiency (X-Linked Ichthyosis)

Question 17

AR condition

mutations in 7-DEHYDROCHOLESTEROL REDUCTASE GENE

Answer 17

Smith Lemli Opitz Syndrome

abnormalities of the CNS, heart, kidney and extremities
w/ ambiguous genitalia
fetal growth restriction

Question 18

AR disease

d.t. abnormality in the cystic fibrosis transmembrane conductance regulator (CFTR) - responsible for chloride channels

Answer 18

CYSTIC FIBROSIS

chronic lung disease d.t. recurrent infections –> irreversible lung damage and strain on right ventricle (COR PULMONALE)

pancreatic insufficiency (85%)

Question 19

AR disease

caused by a SINGLE point mutation in the gene for the BETA chain in hemoglobin –> hemoglobin (Hb S) –> polymers that when deoxygenated –> lose their biconcave shape and sickled appearance

HEMOGLOBIN ELECTROPHORESIS - maternal screen

Answer 19

SICKLE CELL ANEMIA

hemolytic anemia
shortened life expectancy
pain crises

Question 20

AR lysosomal storage disease

absence of the HEXOSAMINIDASE A –> accumulation of GM2 GANGLIOSIDES in the CNS, progressive neurodegeneration and death

brain - GRAY MATTER - highest concentrations of GANGLIOSIDE

Answer 20

TAY SACHS DISEASE

loss of alertness, hyperacusis
progressive developmental delay and neurologic degeneration
myoclonic and akinetic seizures

CHERRY RED SPOT
paralysis, blindness and dementia

Question 21

Typical phenotype of Down Syndrome

Answer 21

short stature
classic facies
developmental delay
mental retardation - 40 - 90

cardiac defects
duodenal atresia
stenosis
short limbs

Question 22

1st trimester screen (TRIPLE SCREEN)

Answer 22

nuchal translucency
PAPP-A
hCG

Question 23

Lethal aneuploidy; nearly all neonates dies in the first 2 years of life

Answer 23

TRISOMY 18 (EDWARD Syndrome)

associated w/ MULTIPLE CONGENITAL ANOMALIES
clenched fists, OVERLAPPING digits and ROCKER BOTTOM FISTS

cardiac defects - VSD, TOF
omphalocele
congenital diaphragmatic hernia
neural tube defects
choroid plexus cysts

Question 24

Has many similar findings w/ Trisomy 18

Answer 24

holoprosencephaly
cleft lip and palate
UMBILICAL HERNIA
cystic hygroma
single nostril or absent nose
omphalocele

cardiac anomalies - hypoplastic left heart
limb anomalies - clubfoot and clubhand, polydactyl and overlapping fingers

Question 25

The MC sex chromosome aneuploidies

Answer 25

``` Turner syndrome (45, X or monosomy X) Klinefelter syndrome (47, XXY) ```

Question 26

Phenotypically FEMALE, SHORT STATURE

Answer 26

Turner syndrome (45, X or monosomy X) primary amenorrhea, sexual infantilism, webbed neck, low set ears, low posterior hairline, epicanthal folds wide carrying angle of the arms, shield like chest wide set nipples short 4th metacarpal renal anomalies lymphedema COARCTATION OF THE AORTA

Question 27

The only anomaly in Turner syndrome seen in ultrasound

Answer 27

CYSTIC HYGROMA

Question 28

Klinefelter syndrome (47, XXY)

Answer 28

infertility gynecomastia mental retardation elevated gonadotropin levels d.t. decreased levels of circulating androgens

Question 29

Formation of neural tube begins on

Answer 29

Days 22-23 (WEEK 4) - 4th and 6th somites ANTERIOR neuropore (FUTURE BRAIN) - closes on day 25 POSTERIOR neuropore (FUTURE SPINAL CORD) - closes on day 27

Question 30

Neural Tube Defects (NTDs)

Answer 30

Spina Bifida | Anencephaly

Question 31

Classic Ultrasound Findings of Spina Bifida

Answer 31

"lemon" sign - concave frontal bones "banana" sign - cerebellum that is pulled caudally and flattened

Question 32

Neural Tube Defects (NTDs)

Answer 32

Spina Bifida | Anencephaly

Question 33

Classic Ultrasound Findings of Spina Bifida

Answer 33

"lemon" sign - concave frontal bones "banana" sign - cerebellum that is pulled caudally and flattened

Question 34

Typically performed b/w 10 and 13 weeks gestation | Specimen is sent for karyotyping or CMS

Answer 34

Chorionic Villus Sampling

Question 35

Results from RENAL FAILURE --> anhydramnios --> pulmonary hypoplasia and contractures/deformations of the limbs in the fetus

Answer 35

Potter Sequence bilateral renal agenesis

Question 36

Kidneys development begins in

Answer 36

WEEK 4 PRONEPHROS MESONEPHROS- WEEK 5 -- mesonephric duct (Wolffian duct) * URETERIC BUD - offshoot of the mesonephric duct that dilates and subdivides to form URINARY COLLECTING SYSTEM (collecting tubules, calyces, renal pelvis and ureter) * (+) testosterone --> mesonephric duct (males) --> vas deferens, epididymis, ejaculatory duct and seminal vesicles * (+) testosterone --> mesonephric duct (females) --> degenerates EXCEPT for the vestigial Gartner's duct METANEPHROS - week 5; WEEK 9 - FUNCTIONING ureteric bud from the mesonephric duct contacts the metanephros and induces it to form nephrons RENAL AGENESIS - failure of contact

Question 37

Renal anomalies that are without much consequence

Answer 37

Horseshoe kidney Ectopic kidney Double ureter

Question 38

Common Risks of Amniocentesis

Answer 38

``` pregnancy loss infection (chorioamnionitis) PPROM fetal injury (w/ needle) exposure to the mother of fetal cells (alloimmunization of mother) ```

Question 39

ELEVATED MSAFP

Answer 39

spina bifida meningomyelocele anencephaly omphalocele gastroschisis previa, accreta

Question 40

Increased incidence of NTD

Answer 40

diabetes | women with seizure disorders - AED - carbamazepine, valproic acid

Question 41

Ultrasound findings in Down syndrome

Answer 41

AV CANAL DEFECT - classic cardiac anomaly PYLORIC STENOSIS