KEY POINTS Print Section Listen Key Points Most common microdeletion syndrome reported in humans. 22q11.2 deletion is associated with DiGeorge syndrome, velocardiofacial syndrome (VCFS), Opitz G/BBB syndrome, and Cayler cardiofacial…
KEY POINTS Print Section Listen Key Points Characterized by tissue-specific presence of an abnormal extra chromosome, which consists of two copies of the short arm of chromosome 12. Abnormal (marker)…
KEY POINTS Print Section Listen Key Points Ninety percent of individuals with Down syndrome have three full copies of chromosome 21. Three to 4% have an unbalanced translocation, and 1%…
KEY POINTS Print Section Listen Key Points Most common chromosomal abnormality that occurs in females. Only 1%of conceptuses with Turner syndrome survive to term. Incidence is 1 in 2500 female…
KEY POINTS Print Section Listen Key Points Trisomies 8,9,14,16, and 20, if present in mosaic form, are compatible with postnatal survival. Mosaic trisomies are generally associated with nondisjunction due to…
KEY POINTS Print Section Listen Key Points Incidence is 1 in 1000 females. Most cases are undiagnosed. Associated with advanced maternal age (70% are due to a meiosis I error)….
KEY POINTS Print Section Listen Key Points Results from meiotic nondisjunction that occurs in the sperm (44% of cases) or egg (56% of cases). About 10% of all cases are…
KEY POINTS Print Section Listen Key Points Second most common autosomal trisomy in liveborn infants. Eighty to 85% of cases result from full trisomy, 10% are mosaics, and 5% are…
