Mosaic trisomy 16 in a fetus: the complex relationship between phenotype and genetic mechanisms.
OBJECTIVE
This study was undertaken to discuss the workup of trisomy 16 pregnancies.


METHODS
This case study reports the prenatal detection and postnatal confirmation of mosaic trisomy 16, associated with uniparental disomy (UPD) 16, in a 34-year-old woman who showed elevated maternal serum alpha-fetoprotein and beta-HCG at a gestational age (GA) of 15.5 weeks.


RESULTS
Amniotic fluid (AF) karyotyping at different GAs revealed various levels of trisomy 16 mosaicism (0 to level III). UPD studies at 21 weeks of gestation revealed maternal heterodisomy 16. Serial fetal ultrasonography showed fetal abnormalities: intrauterine growth restriction (IUGR), dilated digestive tract, and gallbladder agenesis. Postmortem examination confirmed the prenatal findings and revealed additional anomalies, such as hypoplastic cerebellum with abnormal gyration of the vermis.


CONCLUSIONS
Workup following prenatal detection of trisomy 16 mosaicism in chorionic villi must include AF karyotyping and serial ultrasound examination of the fetus in order to approach postnatal developmental prognosis.
Moradkhani
Kamran
K
Department of Medical Genetics, Chu Montpellier, France.
Puechberty
Jacques
J
Blanchet
Patricia
P
Coubes
Christine
C
Lallaoui
Hakima
H
Lewin
Patricia
P
Lefort
Genevieve
G
Sarda
Pierre
P
D000028:Abortion, Induced; D000328:Adult; D000649:Amniocentesis; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D025063:Chromosome Disorders / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000235:genetics*; D002885:Chromosomes, Human, Pair 16; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000235:genetics; D005317:Fetal Growth Retardation / Q000235:genetics; D006801:Humans; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D010641:Phenotype; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods; D014314:Trisomy; D014463:Ultrasonography; D000509:alpha-Fetoproteins / Q000032:analysis
D018997:Chorionic Gonadotropin, beta Subunit, Human; D000509:alpha-Fetoproteins