Pathogenesis
most common cause of Down syndrome
Nondisjunction
Trisomy 21 (nondisjunction) accounts for approximately what % of cases
95%
Which test is invasive and carries moderate to high miscarriage risk?
amniocentesis
what is the most common cardiac defect a patient with down syndrome could have?
AV septal defect
Full Trisomy 21 (Nondisjunction) accounts for what % of cases
about 95%
The main consequence of nondisjunction is:
extra copy of a chromosome
Which down syndrome type can be inherited from a parent
Translocation Down syndrome
what is a nuchal skin fold
normal fold of skin seen at the back of the fetal neck
What is hypotonia?
Weak muscle tone
what is the karyotype nomenclature for down syndrome
47,XX,+21 or 47,XY,+21
In translocation Down syndrome, what happens to the extra chromosome 21 material?
attached to another chromosome (14)
Which type of down syndrome is strongly linked to increased maternal age
Full trisomy 21 (nondisjunction)
Which pattern on quad screen suggests Down syndrome?
↓ AFP, ↑ β-hCG, ↓ estriol, ↑ inhibin A
What is duodenal atresia?
duodenum doesn’t develop properly causing a blockage, preventing food from passing through
epicanthal fold
Robertsonian translocation typically involves which chromosomes?
14 and 21
What type of down syndrome occurs when not all but only some cells in the body have an extra copy of chromosome 21
Mosaic down syndrome
Why is amniocentesis high risk?
causes risk of miscarriage due to infections, bleeding, or sac damage
What types of Leukemia can a patient with Down Syndrome be at higher risk for?
↑ risk of acute lymphoblastic leukemia (ALL) & acute myelogenous leukemia (AML).
what are the small, white spots in a patient with down syndrome's eye?
brushfield spots
Anaphase lag may result in what type of cells
Trisomic or monosomic cells
Translocation Down syndrome accounts for approximately what % of cases
3-4%
in chorionic villus sampling (CVS), samples of what are collected?
placental tissue
What is Hirschsprung’s disease?
nerve cells are missing from large intestine preventing muscle contractions causing problems with passing stool
What clinical feature is seen in a patient with down's syndromes palm?
single palmar crease