Chapter 20: Prenatal Testing and Reproductive Genetics Flashcards
(20 cards)
Amniocentesis
Gestational age of performing: 15-16 weeks of gestation
Aspiration of 10-30ml of amniotic fluid from amniotic sac, through abdominal wall under ultrasound guidance
Fetal skin cells are collected by centrifugation and then cultured for two weeks in an incubator
The chromosomes from these fetal skin cells are harvested and reated with hypotonic fixative solution
The fetal cells can be directly used for FISH test
Risk for miscarriages: 0.5-1%
Amniotic Fluid
The protective liquid contained by the amniotic sac
Cushion for the fetus
Trophoblast
The outer cell mass of the early embryo that gives rise to the placenta
Inner Cell Mass
the mass of cells inside the primordial embryo that will eventually give rise to the definitive structures of the fetus
Chorionic Villus
Layer of cells covering a fertilized ovum, some of which will later form the placenta
Maternal Cell Contamination
When during sampling, some of the mother’s cells are taken as well as the fetus
Chorionic Villus Sampling
the trophoblast layer of the chorionic villus belongs to the fetus, and thus is the targeted tissue in this testing
11 weeks gestation
Risk for miscarriage : 1-2%
Other problem: maternal cell contamination
Transcervical or transabdominal aspiration
Ultrasound used to guide procedure
Miscarriage
Also called spontaneous abortion
An event that results in the life of the fetus before 20 weeks
Gestation
The process of carrying, or being carried in the womb between conception and birth
Maternal decidua
The decidua is the modified mucosal lining of the uterus (that is, modified endometrium) that forms in preparation for pregnancy. It is formed in a process called decidualization under the influence of progesterone. … The decidua forms the maternal part of the placenta and remains for the duration of the pregnancy.
Aneuploidy
A chromosome number that is not an exact multiple of the haploid number
fluorescent in situ hybridization
Use of a single-stranded DNA sequence with a fluorescent label to hybridize with its complementary target sequence in the chromosomes, allowing it to be visualized under ultraviolet light
Ultrasonography
The use of ultrasonic sound waves to image objects at a distance (e.g. the developing fetus in utero)
Nuchal translucency
Refers to the assessment of the quality of fluid collecting within the nape of the fetal neck, usually from an ultrasound scan around the end of the first trimester
Maternal Serum Screen
Is done around 16 weeks gestation (between 11 and 16)
Neural Tube Defect and Down Syndrome
Alpha fetoprotein
the fetal equivalent of albumin and is the major protein in the fetal blood
In NTD it is higher, in Down syndrome, it is lower
Folic Acid
The synthetic form of folate which helps to form DNA and other genetic material
Women trying to get pregnant should take up to 400 micrograms folic acid daily until after the first trimester
Newborn screen program
In Georgia, each newborn will be tested for some severe diseases
A blood sample will be collected from a baby by pricking its heel
The blood is then put on a piece of paper and air dried
Dry blood is sent to the lab for testing
+ test is sent to another lab to rule out false positive
31 diseases tested in GA including PKU, sickle cell anemia, and CF
critical to be tested within 24-48 hours
Non-invasive Prenatal Diagnosis (NIPD)
Cell free DNA screening Can detect Trisomies 21, 13, 16, 18, 22 Triploidy Sex chromosome aneuploidy Achondroplasia (FGFR3 gene mutation) Some craniosynostosis (FRFR2 mutation) Not effective if obese, multiples, donor egg, or less than 10 weeks pregnant
NTD
Neural Tube Defect
The closure of the spinal cord is abnormal
most severe form is anencephaly
Can be caused by trisomy 13 or 18. Or lack of folic acid
Girls more often
Race: spina bifida is more common among whites and Hispanics
