Carrier Screening Flashcards
What are the three major conditions for which we offer screening/testing in reproductive settings?
Gene variant conditions
CHROMOSOME conditions
Fetal anatomical development conditions
What Gene variant conditions tests assessed?
Whether a parent or prospective parent is a carrier of gene variants/mutations (changes in a genetic sequence that alters the structure or function of proteins e.g. sickle-shaped red blood cells or excessive mucus).
If a parent or prospective parent is a carrier and has offspring with another carrier, the offspring can be at increased risk for certain autosomal recessive disorders.
When are Gene variant conditions tests completed?
Test can be performed on a prospective parent during the preconception period OR on an expecting parent during pregnancy.
Example of Gene variant conditions
Cystic fibrosis;
spinal muscular atrophy
What CHROMOSOME conditions tests assessed?
Whether a fetus has been conceived with a different number of chromosomes than usual.
When are CHROMOSOME conditions tests completed?
Performed after pregnancy is underway (timing varies with the type of test)
Example of CHROMOSOME conditions
Trisomy 21 (Down Syndrome);
Trisomy 13
What Fetal anatomical development conditions tests assessed?
Whether a fetus has developed physically in a different way/with an unusual difference.
When are fetal anatomical development conditions test completed?
Performed after pregnancy is underway, most often during the second trimester
What are examples of fetal anatomical development conditions
Neural tube defects e.g. spina bifida
What are the three general approach to screening
Ethnic-specific/targeted
Pan-ethnic/nondirective
Expanded
What does Ethnic-specific/targeted screening approach entails
Screens for:
conditions considered to be common in the ethnic group with which the patient identifies
conditions identified through family history
Examples for conditions included in Ethnic-specific/targeted screening
Tay-Sachs: individuals of Ashkenazi Jewish, Cajun, or French-Canadian descent
Canavan disease and familial dysautonomia: individuals of Ashkenazi Jewish descent
Fragile X syndrome: Individuals with a family history of intellectual disability suggestive of fragile X syndrome
What does Pan-ethic/nondirective screening entail?
Screens all patients for specific conditions, regardless of identified ethnic group or ancestry
Examples of conditions included in Pan-ethic/nondirective screening.
Cystic fibrosis
Spinal muscular atrophy
Hemoglobinopathies
