Ch. 30 Chromosomal Abnormalities Flashcards
_______are the structures, located in each cell in our body, that hold our genes.
Chromosomes
an error in either the number or structure of chromosomes
chromosomal abnormality
The normal cell has ____chromosomes or two pairs of ____.
46; 23
_______ is a condition in which there are an abnormal number of whole chromosomes. Specifically, an aneuploid has too many or too few chromosomes.
Aneuploidy
chromosomal aberration in which there is a third chromosome 18
Edwards syndrome
a cell having three copies of an individual chromosome
trisomy
Turner syndrome, also referred to as _______ X, is a different type of chromosomal abnormality in which the fetus has only one sex chromosome.
monosomy
a chromosomal aberration where one sex chromosome is absent; may also be referred to as monosomy X
Turner syndrome
_______ and ______ have been suspected to increase the likelihood of chromosomal abnormalities.
Environmental factors; maternal age
is a structural feature that differs from the norm. An example of an ______ is agenesis of the corpus callosum in which there is congenital absence of an important midline brain structure.
anomaly
the congenital absence of corpus callosum that may be partial or complete
agenesis of the corpus callosum
a group of clinically observable findings that exist together and allow for classification. These signs and symptoms are linked to each other in some way.
syndrome
_______has clinically identifiable signs such as a flat facial profile and a transverse crease in the palm of the hand. An example of symptoms of _______would be developmental delays and hearing loss.
Down syndrome
a structural abnormality that results from an abnormal development
malformation
_________is a congenital brain malformation that is thought to be caused by a developmental deviation in the roof of the fourth ventricle.
Dandy–Walker malformation
congenital brain malformation in which there is enlargement of the cisterna magna, agenesis of the cerebellar vermis, and dilation of the fourth ventricle
Dandy–Walker malformation
The three laboratory values that typically comprise the triple screen are ______, _______, and ______.
MSAFP, estriol, and hCG.
AFP is produced in the ______and fetal liver. Estriol and hCG are produced by the _______.
yolk sac; placenta
This simple blood test can reveal gender and is also highly accurate in detecting chromosomal anomalies, including trisomies 21, 18, and 13 and sex chromosome abnormalities, as early as 9 weeks’ gestation.
cell-free DNA testing
the most common cause of abnormal serum screening tests is _______ of the pregnancy.
incorrect dating
Advanced maternal age is considered to be ______ years or older.
35
an analysis of fetal chromosomes; reveals the morphology and number of chromosomes
Fetal karyotyping
the form and structure of an organism
morphology
During pregnancy, a sample of maternal blood, amniotic fluid, or tissue from the placenta can be used for fetal karyotyping. There are three main procedures used to obtain material for fetal karyotyping: ______,_______,_______
(i) chorionic villi sampling (CVS), (ii) amniocentesis, and (iii) cordocentesis
prenatal test used that obtains placental tissue for chromosomal analysis
chorionic villi sampling
a surgical procedure in which amniotic fluid is extracted for genetic testing or removed when there is an accumulation of an excessive amount of fluid around the fetus
amniocentesis
prenatal test that obtains fetal blood for chromosomal analysis
cordocentesis
_______ typically the earliest procedure that can be performed during a pregnancy for fetal karyotyping. With _____, a small amount of _______is obtained for chromosomal testing. Can be performed transabdominally or transvaginally (transcervical) between ____ and ____ gestational weeks. Under sonographic guidance, a needle or plastic catheter is placed into the placental mass for the aspiration of trophoblastic cells
CVS; chorionic villi; 10 and 13
the cells that surround the gestation that produce human chorionic gonadotropin
trophoblastic cells
Some research links a possible association between CVS performed less than 10 weeks and _______abnormalities.
fetal limb
Amniocentesis is typically used for genetic purposes between ____and ____ weeks. Some facilities may offer this procedure to patients as early as 10 weeks, although some studies suggest that it should not be done before 15 weeks because of an increase in fetal complications.
15 and 20
An amniocentesis is performed ______ with sonographic guidance. The physician inserts a 20 to 22G needle through the abdomen and into the amniotic sac to remove amniotic fluid for testing. The most common side effects of this procedure are ______ and ______. Rarely, patients experience vaginal spotting, amniotic fluid leakage, or amnionitis. (may take as many as 3 wks for results)
transabdominally; uterine contractions and cramping
inflammation of the amniotic sac secondary to infection
amnionitis
An amniocentesis may also be performed to assess the fetal ____for maturity by obtaining fluid and testing the lecithin-to-sphingomyelin ratio (L/S ratio). Also, a ______ amniocentesis can be performed to remove excess amniotic fluid or to distend the amniotic cavity with more fluid when scant fluid is noted around the fetus.
lungs; therapeutic
Cordocentesis, also referred to as _______ (PUBS) or fetal blood sampling, is performed transabdominally after 17 weeks.
percutaneous umbilical cord sampling
For PUBS, a needle is placed through the maternal abdomen and into the umbilical vein. The segment of the cord that is most often accessed is at the cord insertion point into the ______.
placenta
A sample of fetal blood is removed. PUBS has been associated with fetal _______ and _______ at the sampling site. It also carries a _____ fetal loss rate compared to amniocentesis. PUBS allows for _____ detection of chromosomal anomalies, because it requires only 48 to 72 hours for analysis.
bradycardia, hemorrhage, higher, rapid
fingerlike projections of gestational tissue that attach to the decidualized endometrium and allow transfer of nutrients from the mother to the fetus
chorionic villi
A cell having three times the normal haploid number. There are 69 chromosomes.
Triploid
A situation in which some cells have an abnormal number of chromosomes whereas others do not.
Mosaic
A cell having only one of an individual chromosome.
Monosomy
A cell having only one member of each pair of chromosomes
Haploid
A cell having the normal pair of each chromosome. There are 46 chromosomes in this situation. Normal cells are diploid, with the exception of the gametes.
Diploid
_________or trisomy 21, is the most common chromosomal abnormality. It occurs in 1 in 500 to 800 pregnancies.
Down syndrome
Maternal Serum Screening Results of _________
Low MSAFP
Low estriol
High hCG
High inhibin A
Low PAPP-A
Down Syndrome