Trisomy 16

Epidemiology and Etiology:

· Maternal meiosis I possibly in every case

· Increased risk with increased maternal age

· mosaicism is often seen

· confined placental maybe

· May be associated with maternal UPD 16, which may have a phenotype associated

Common sites:

·

Gross features:

· Mosaicism at amnio:

· IUGR

· Congenital heart defect

· Other minor anomalies

Histologic features:

·

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

·

Other features:

· Placental insufficiency

· Poor pregnancy outcome very often

· Mosaicism at CVS

· Only 28% had a normal full-term pregnancy outcome

· Fetal death in utero in some

· Mosaicism on amnio has a high risk of abnormal phenotype (70-90%)

· DD

· Congenital abnormalities (see above)

References:

· Gardner RJM, Sutherland GR. Chromosome abnormalities and genetic counseling. Oxford University Press; 2004.