SM_213b: Reproductive Genetics Flashcards
Carrier screening ____
Carrier screening determines carrier status in healthy people in high-risk populations
Prenatal screening ____
Prenatal screening identifies whether a fetus is at increased risk for chromosomal abnormality, NTDs, Down syndrome, or spina bifida
Newborn screening ____
Newborn screening can detect treatable genetic disorders that could prove dangerous if left untreated
Diagnostic tests ____ while screening tests do not
Diagnostic tests give a definitive answer while screening tests do not
Describe goals of prenatal screening and testing
Goals of prenatal screening and testing
- Provide a range of informed choice to couples at risk of having a child with an abnormality
- Provide reassurance and reduce anxiety, especially among high-risk groups
- Expand the childbearing options for couples at risk of having a child with a birth defect / syndrome
- Asssist with management of a pregnancy with a genetic disorder
- Enable prenatal treatment of the affected fetus
Describe red flags in family histories
Red flags in family histories
- Known or suspected genetic disease
- Multiple malformations
- Multiple miscarriages
- Recurrence of same / similar disorders
- Intellectual disability / ASDs
- Consanguinity
Describe indications for prenatal diagnosis by invasive testing
Indications for prenatal diagnosis by invasive testing
- Advanced maternal age: ≥ 35 years old at time of delivery
- Previous child with a de novo chromosome abnormality
- Presence of structural chromosome abnormality in one of the parents
- FMHx of a genetic disorder
- Risk of NTD
- Abnormal prenatal screening result
- Older paternal age
- FMHx of a genetic disease
- Parental aneuploidy or aneuploidy mosaicism
- Prior child with a structural birth defect
- Desire for prenatal diagnosis / maternal anxiety
- Abnormal sonogram (fetal anomalies)
Describe methods of invasive prenatal diagnosis
Methods of invasive prenatal diagnosis
- Chorionic villus sampling: placental biopsy
- Amniocentesis: obtain amniotic fluid cells
- Cordocentesis: sample of fetal blood from umbilical cord
Most cases of chorionic villus mosaicism are ____
Most cases of chorionic villus mosaicism are confined placental mosaicism
- Only 20-33% are true mosaics
Describe common aneuploidies in liveborns
Common aneuploidies in liveborns
- Trisomy 21 (Down syndrome): 1 in 700
- Trisomy 18 (Edwards syndrome): 1 in 3000
- Trisomy 13 (Patau syndrome): 1 in 5000
- 45X (Turner syndrome): 1 in 2500 females
- 47XXY (Klinefelter syndrome): 1 in 600 males
- 47XYY and 47XXX: 1 in 1500
For autosomal trisomies, recurrence risk is ____
For autosomal trisomies, recurrence risk is 1% until age-related risk exceeds 1%
Quad screening is ____
Quad screening is MSAFP, hCG, unconjugated estriol, and inhibin A for Down syndrome, Trisomy 18, open NTDs
(second trimester: 15 to 21-6/7 weeks)
First trimester screen involves risk assessments for ____, ____, and ____
First trimester screen involves risk assessments for Down syndrome, Trisomy 18, and Trisomy 13
(11 to 13-6/7 weeks)
Carrier screening has the purpose of ____
Carrier screening has the purpose of identifying couples at risk for passing on genetic conditions to their offspring
- Important component of preconception and prenatal care
- Typically autosomal recessive or X-linked
Multifactorial inheritance is ____
Multifactorial inheritance is the combined contribution of one or more often unspecified genes and environmental factors, often unknown, in the causation of a particular trait or disease
- Open NTDs
Chromosomal aneuploidy is particularly common in ____
Chromosomal aneuploidy is particularly common in cystic hygroma
Risk for chromosomal abnormality is ____ for trisomies than microdeletions / duplications
Risk for chromosomal abnormality is greatest for trisomies than microdeletions / duplications
