Prenatal diagnosis of mosaic trisomy 16 associated with congenital diaphragmatic hernia and elevated maternal serum alpha-fetoprotein and human chorionic gonadotrophin.
OBJECTIVE
To present the clinical, cytogenetic, and molecular findings of prenatally diagnosed mosaic trisomy 16.


METHODS
A 30-year-old gravida 2, para 1 woman was referred for amniocentesis because of a positive maternal serum screen result with elevated maternal serum alpha-fetoprotein (MSAFP) and maternal serum free beta-human chorionic gonadotrophin (MSfreebeta-hCG). Cytogenetic analysis of amniotic fluid at 21 weeks' gestation revealed mosaicism for trisomy 16, 47,XX,+16[3]/46,XX[15]. Ultrasonography demonstrated right diaphragmatic hernia and agenesis of left umbilical artery. The pregnancy was terminated subsequently. The karyotype of the cord blood was 46,XX. Cytogenetic analyses of the multiple sampled tissue specimens showed a karyotype of 47,XX,+16 in the placenta and 47,XX,+16/46,XX with various levels of trisomy 16 in the umbilical cord and skin. Molecular studies showed that the trisomy 16 in the placenta was likely to have resulted from a maternal meiosis II nondisjunction error. Partial dosage increase of an extra maternal allele was noted in the skin and umbilical cord.


CONCLUSIONS
Fetuses with mosaic trisomy 16 may be associated with congenital diaphragmatic hernia and elevated MSAFP and MShCG. Fetal blood sampling is of a limited value in confirming mosaic trisomy 16 ascertained through amniocentesis.
Chen
Chih-Ping
CP
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan, Republic of China. cpc_mmh@yahoo.com
Shih
Jin-Chung
JC
Chern
Schu-Rern
SR
Lee
Chen-Chi
CC
Wang
Wayseen
W
D000028:Abortion, Induced; D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D002885:Chromosomes, Human, Pair 16; D003937:Diagnosis, Differential; D005260:Female; D005838:Genotype; D006551:Hernia, Hiatal / Q000150:complications / Q000175:diagnosis* / Q000196:embryology; D006801:Humans; D008297:Male; D010375:Pedigree; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis; D014314:Trisomy / Q000175:diagnosis* / Q000235:genetics; D000509:alpha-Fetoproteins / Q000378:metabolism
D018997:Chorionic Gonadotropin, beta Subunit, Human; D000509:alpha-Fetoproteins