Chpt 30: Chromosomal Abnormalities

chromosomes are located in each ___ that hold our genes

cell

chromosomal ___ is an error in the number or structure of chromosomes

abnormality

Normally there's ___ chromosomes per cell which is ___ pairs

46 chromosomes

23 pairs

What are trisomy 13, 18, and 21 called?

patau, edward, down's

What is a syndrome in which the fetus has 1 sex cell chromosome? 2 names

Turner syndrome

Monosomy X

Term: cell has abnormal amount of chromosomes (too many or too few)

aneuploid

Term: cell has normal pair of each chromosome (46 total)

diploid

Term: cell has 1 member of each pair of chromosome

haploid

Term: cell has only 1 of an individual chromosome

Monosomy

Term: some cells have an abnormal number of chromosomes, where others don't

Mosaic

Term: Cell has 3x the normal haploid number, there are 69 total chromosomes

Triploid

Term: Cell has 3 copies of an individual chromosome

trisomy

Term: a structural feature that differs from the norm

anomaly

Term: a group of clinically observable findings that exist together

syndrome

Term: a structural abnormality that results from unusual development

malformation

Triple screen can detect chromosomal abnormalities. What are the 3 labs tested and what are they produced by?

- estriol by the placenta

- hcg by the placenta

- afp by fetal yolk sac & liver

Triple screen has a __% detection rate for Down's syndrome

60

What is the most common cause for an abnormal screening test?

incorrect dates

Which two labs can also be added to the triple screen?

- pregnancy associated plasma protein A (Papp-A)

- Inhibin A

What produces papp-a and inhibin-a?

placenta

____ is a newer blood test for gender and highly detectible for chromosomal abnormalities

cell free dna testing

Advanced maternal age is __ years old

35+

Advanced maternal age has a higher risk for (2)

- pregnancy loss

- abnormal pregnancy

Fetal karyotyping is recommended for advanced maternal age patients. This is an analysis of the fetal ____

chromosomes

Karyotyping can be done by sampling maternal (3)

blood, amniotic fluid, or tissue from placenta

What are the 3 main procedures for karyotyping?

- chorionic villi sampling

- amniocentesis

- cordocentesis

What is the earliest procedure that can be done for karyotyping?

chorionic villi sampling

define: fingerlike projections of gestational tissue that attach to the decidualized endo and allow transfer of nutrients from mom to baby

chorionic villi

Chorionic villi sampling (CVS) can be done TA or TV between which weeks?

10-13 weeks

With CVS, a needle or plastic catheter is placed into the ___ for aspiration of ___ cells

placenta, trophoblastic

Define the procedure: needle inserted through abdomen into amniotic sac to remove fluid with fetal cells

amniocentesis

When can an amniocentesis be done?

15-20 weeks

Is an amniocentesis guided TA or TV?

TA

2 most common side effects of an amnio are:

uterine cramping and contractions

3 rarer side effects of an amnio:

vaginal spotting

amniotic fluid leakage

amnionitis

Amniocentesis can also be done to test ___ maturity

lung

amniocentesis can be done for therapeutic purposes to ___ fluid

remove or add

define: needle inserted thru mom's abdomen into the umbilical vein

cordocentesis

2 other names for cordocentesis

- percutaneous umbilical cord sampling (PUBS)

- fetal blood sampling

is cordocentesis guided TA or TV? after how many weeks?

TA, 17 weeks

What is the most common region for the umbilical cord to be sampled?

at the PCI

2 fetal complications of pubs/cordocentesis

- bradycardia

- hemorrhage at the sampling site

Is there a higher fetal loss rate with an amnio or cordo?

cordo

What's one benefit of a cordocentesis?

higher turn around time, results in 48-72 hours

What's the most common chromosomal abnormality?

Down Syndrome

What labs are low vs high with down syndrome?

Low - MSAFP, Estriol, Papp-A

High - HCG, Inhibin A

5 head/face findings with down syndrome

- Absent nasal bone

- Brachycephaly (round head)

- mild ventriculomegaly

- macroglossia

- nuchal thickening

4 extremity findings with down syndrome

- clinodactyly (curved pinky)

- sandal gap toes

- short femur/humerus

- widened pelvic angles

4 abdomen findings with down syndrome

- pyelectasis

- echogenic bowel

- duodenal atresia

- nonimmune hydrops

3 heart findings with down syndrome

- echogenic intracardiac foci

- pericardial effusion

- vsd

what is the 2nd most common chromosomal abnormality

edwards syndrome / trisomy 18

Do most fetuses with trisomy 18 make it alive?

no, usually die before birth or shortly after

Are all lab values increased or decreased with edwards syndrome?

ALL DECREASED

HCG, PAPP-A, inhibin a, estriol, afp

8 head/face findings with trisomy 18

- Strawberry skull

- Agenesis of corpus callosum

- Choroid plexus cysts

- hypoplastic cerebellum

- enlarged cisterna magna

- hydrocephalus (incr CSF in ventricles)

- micrognathia

- small low set ears

6 abdomen findings with trisomy 18

- esophageal atresia

- omphalocele

- nonimmune hydrops

- diaphragmatic hernia

- renal anomalies

- single umbilical artery

4 limb/spine findings with trisomy 18

- clenched hands

- spina bifida

- ROCKER BOTTOM FEET

- clubfeet

2 cardiac findings with trisomy 18

- tetralogy of fallot

- vsd

Patau syndrome/trisomy 13 is usually __

fatal

Are maternal serum screenings helpful in detecting trisomy 13?

no :(

Key findings of Patau Syndrome (7)

- microcephaly

- polydactyly

- holoprosencephaly

- cyclopia

- cleft lip/palate

- micropthalmia

- hypotelorism

Define: fetus has 69 chromosomes instead of 46

Triploidy

Triploidy babies usually die when?

in the first tri or early second tri

What is often found in coexistence with triploidy?

partial molar

resulting in markedly high hcg and bilateral theca lutein cysts

4 sono findings of triploidy

- small low set ears

- cardiac defects

- syndactyly (webbed)

- IUGR

Turner syndrome is aka... (3)

- monosomy x

- x

- 45

turner syndrome is found in what gender?

females

2 most common presentation of turner syndrome

- nuchal cystic hygroma

- nonimmune hydrops

Nonimmune hydrops is fluid build up in at least __ body cavities

2

Lab findings of turner syndrome

all labs low!!

Low hcg, estriol, afp, Papp-A, inhibin A

Most common sono finding of turner syndrome

Large septated cystic hygroma along the neck!

6 other possible anomalies found with Turner syndrome

- ovarian dysgenesis

- webbed neck!

- short stature

- motor defects

- hearing loss

- renal anomalies

Klinefelter syndrome is male chromosomal abnormality... aka (2)

- 47

- XXY

5 presentations of klinefelter syndrome

- Hypogonadism (unable to produce enough sex hormones)

- Small testis

- tall stature

- gynecomastia

- intellectual disability