Chromosomal Abnormalities Flashcards
Aneuploidy
State of having an abnormal number of chromosomes
- 1 extra or 1 less
Trisomy
One extra complete or partial chromosome
If you have trisomy how many chromosomes will you have
47
Triploidy
A complete extra set of chromosomes
What is triploidy a form of
Polyploidy
How many chromosomes will you have if you have triploidy
69
Turners syndrome
Missing an x or y from the paternal side
What is turners syndrome called
Monosomy
How many chromosomes do you have if you have turners syndrome
45xo
What is the meotic error that causes aneuploidy called
Non-disjunction
What is non-disjunction
When the chromosome pair fails to separate during meiosis
What does the sperm to oocyte have 2 copies of or no copies of? And it is instead of one copy in what state?
A particular chromosome
-haploid
Once fertilization occurs the zygote will have how many chromosomes if it has aneuploidy
45 or 47
What is the most common live born chromosome abnormality
Trisomy 21
What is the most common chromosome abnormality among spontaneously aborted fetuses
Turner’s syndrome
Trisomy 18 and 13 are more severe than
Trisomy 21
What other kind trisomies are rarely seen because of the lethal result and early pregnancy loss
Autosomal
What is another name for trisomy 21
Down syndrome
What is the major cause of increased mortality in trisomy 21 infants
Cardiac abnormalities
Trisomy 21 people will have decreased what, and does the severity vary?
Intelligence and yes
Is trisomy 21 considered lethal
No
What kind of test for trisomy 21 has a 60% detection rate
Triple screen
What is the sonographic appearance of trisomy 21
- thick nuchal fold
- heart defects
- mild renal dilatation >/5mm
- Duodenal atresia or TE fistula
- shortened long bones
Pelviectasis is also called
Pyelectosis
What are the less specific sonographic appearance of T21
Cystic hydroma Non immune hydrops Clinodactyly Echogenic bowel Omphalocele Mild ventriculomegaly Sandal foot toes
What will the triple screen test show for T21
MSAFP decreased
B hCG increased
UE3 decreased
What will the triple screen show for T18
MSAFP decreased
B hCG decreased
UE3 decreased
What will the triple screen show for T13
Nothing, as it cannot be predicted with the triple screen
What values are tested in the quad screen
AFP
UE3
B hCG
Inhibin A
What is UE3
Unconjugated estriol
An increase in Inhibin A is suggestive of what
Down syndrome
What are the biochemical markers at 1st trimester screen
B-hCG
PAPP-A
What is PAPP-A
Pregnancy associated plasma protein
What will the biochemical markers be at first trimester screen if the fetus has T21
B-hCG increased
PAPP-A decreased
What is another name for T18
Edwards syndrome
Trisomy 18 is almost always
Lethal or a very poor prognosis
Survivors of T18 will have profound what
Mental retardation
Why does T18 have a poor prognosis
Because of the heart and GI abnormalities
T18 is the 2nd most common what
Chromosomal abnormality seen at birth
What is T18 associated with
LMA
What is the sonographic appearance of T18
Early onset of SYMMETRIC IUGR w/ polyhydramnios Clenched fists and/or clinodactyly Club feet and/or rocker bottom feet CPC’s Heart defects
What is the most common heart defect seen in a fetus that has T18
Large VSD
What are the less specific sonographic appearances of T18
Cleft lip and/or palate Omphalocele Diaphragmatic hernia Single umbilical artery STRAWBERRY SHAPED HEAD Radial ray syndrome Micrognathia Cystic hygroma Enlarged cisterna magna
What is radial ray syndrome
A absent radius resulting in a clubbed hand
What is another name for trisomy 13
Patau syndrome
What is the prognosis for T13
Lethal or very poor
What will survivors of T13 have
Profound mental retardation
T13 is the 3rd most common what
Chromosomal abnormality seen at birth
A mother with advanced maternal age will have a increased risk for having a fetus with
T13
What is the sonographic appearance of T13
Midline defects
-holoprosencephaly
What is holoprosencephaly
Severe abnormality of the forebrain cleavage
Holoprosencephaly is the fusion of
The cerebral hemispheres and thalami
What are the 3 classifications for holoprosencephaly
Lobar
Semilobar
Alobar
Alobar holoprosencephaly is when
There is little or no cortical mantle
Single horseshoe shaped ventricle
Fused thalami
Absent 3rd ventricle and falx
What is semilobar holoprosencephaly
Single horseshoe shaped ventricle with brain mantle
Incomplete fusion of the thalami
Absent falx and 3rd ventricle
What is lobar holoprosencephaly
Fused anterior horns, that are squared off
Incomplete falx
3rd ventricle may be seen
What are the sonographic features of T13
Cleft lip and/or palate -unilateral/ bilateral/ midline Eyes -micropthalmia -hypotelorism -Cyclopia Abesent nose or nose replaced with proboscis Omphalocele Microcephaly IUGR
What are the less specific sonographic features
Polydactyly Clinodactyly Club feet Rocker bottom feet Cystic hygroma Severe heart defects Polycystic kidneys Enlarged cisterna magna
Triploidy is
Rare and usually lethal
Partial molar pregnancy
Triploidy is not
Associated with maternal age
Parental triploidy will
Hal=EV half miscarry
Large hydropic placenta
Small symmetrical IUGR
Increased hCG
Maternal triploidy will have
More live births
Small placenta
Asymmetric IUGR
2nd trimester low hCG due to small placenta
What is the sonographic appearance of triploidy
Holoprosencephaly Agenesis of the corpus callosum Meningomyelocele Arnold chiari malformation Ventriculomegaly Heart defects Facial clefts Syndactyly Club feet Cystic hygroma Omphalocele
Triploidy will have what kind of placenta
Thick with cystic areas
Turner’s syndrome patients are all what
Female
Is maternal age a factor for turners syndrome
No
Turners syndrome are missing one what
Sex chromosome
Turners syndrome is the most common
Chromosomal abnormality in spontaneous aborted fetuses
If a turners syndrome fetus lives what will they have
Few life threatening anomalies
Normal intellect
What is the sonographic appearance of turners syndrome
Cystic hydrops Hydrops Heart defects Renal agenesis Horseshoe kidney Pelvic kidney
What is most common heart defect in a turners syndrome fetus
Coarctation of the aorta