Pathogenesis
This is the most common chromosomal abnormality causing Down syndrome.
What is full trisomy 21?
This second-trimester protein is decreased in maternal serum when the fetus has trisomy 21.
What is alpha-fetoprotein (AFP)?
Weak muscle tone present in newborns with Down syndrome.
What is hypotonia?
Down syndrome occurs in approximately 1 in this many live births worldwide.
What is 1 in 700 to 1,000?
This type of therapy can help infants with Down syndrome achieve developmental milestones earlier.
What is early intervention therapy?
This mechanism occurs when paired chromosome 21 homologs fail to separate properly during meiosis.
What is nondisjunction?
In the quad screen, both hCG and this hormone from the corpus luteum and placenta are increased in Down syndrome.
What is inhibin A?
Individuals with Down syndrome have increased risk for this neurodegenerative disorder, often developing before age 60.
What is early-onset Alzheimer’s disease?
This maternal factor increases the risk of nondisjunction.
What is advanced maternal age (>35 years)?
Children with Down syndrome have a higher lifetime risk of developing this blood sugar disorder.
What is diabetes mellitus?
This form of Down syndrome results from a post-fertilization mitotic error, leading to some cells being normal and some trisomic.
What is mosaicism?
This first-trimester ultrasound finding—measuring fluid at the back of the fetal neck—is increased in trisomy 21.
What is nuchal translucency?
Flattened facial profile, upslanting palpebral fissures, and epicanthic folds are all examples of these in Down syndrome.
What are characteristic facial features?
This category of influences has not been identified to cause DS.
What is environmental factors?
This gastrointestinal abnormality, requiring surgery, is seen more often in babies with Down syndrome.
What is duodenal atresia?
This rarer chromosomal abnormality involves the long arm of chromosome 21 attaching to another chromosome, usually chromosome 14.
What is Robertsonian translocation?
This non-invasive screening method analyzes cell-free fetal DNA in maternal blood.
What is non-invasive prenatal testing (NIPT)?
Children with Down syndrome have increased risk for this hematologic malignancy, especially the acute megakaryoblastic type.
What is leukemia?
Down syndrome is the most frequently occurring aneuploidy that is capable with this.
What is survival beyond infancy?
This spinal instability in some patients with Down syndrome can cause spinal cord injury if untreated.
What is atlantoaxial instability?
This rare mechanism occurs when two long arms of chromosome 21 separate together instead of a long and short arm.
What is isochromosome 21?
This invasive procedure, usually performed between 15–20 weeks, collects amniotic fluid for karyotype analysis.
What is amniocentesis?
Nearly 50% of infants with Down syndrome are born with these heart problems, especially atrioventricular septal defects.
What are congenital heart defects?
This rare prenatal cause can lead to familial recurrence risk of Down syndrome even in younger mothers.
What is Robertsonian translocation?
Due to advances in medical and supportive care, individuals with Down syndrome now have this prognosis trend.
What is increased life expectancy?