Trisomy 21

2006-08-30-8 Heron Werner, MD\ Clínica de Diagnóstico por Imagem (CDPI) – Rio de Janeiro – Brazil

Trisomy 21 is an abnormality due to the presence of an extra copy of chromosome 21. It is the most common single cytogenetic aberration in live born infants. This chromosomal disorder occurs around 1:800 liveborn. First trimester screening has a detection rate of 80% with 5% false positive. The risk factors include:

The diagnosis can be done by karyotyping fetal cells obtained by chorionic villus sampling, amniocentesis or cordocentesis.

Fetal profile with prominent tongue.
Fetus with trisomy 21 at 28 weeks. In the face (3D view) note the prominent tongue, relative nasal hypoplasia and small mouth.
Hands view shows short phalanges and hypoplasia of mid phalanx of fifth finger. Axial view of the abdomen showing the duodenal atresia.
Axial view of the thorax showing right hydrothorax. Complete atrioventricular septal defect.

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