Prenatal diagnosis of de novo proximal interstitial deletion of 9q and review of the literature of uncommon aneuploidies associated with increased nuchal translucency.
OBJECTIVE
To present the prenatal diagnosis and molecular cytogenetic analysis of de novo proximal interstitial deletion of 9q and to review the literature of uncommon aneuploidies associated with increased nuchal translucency (NT).


METHODS
Obstetric ultrasound at 11 weeks' gestation revealed an increased NT thickness of 6.6 mm in a 31-year-old primigravid woman. At 13 weeks' gestation, repeat ultrasound examinations revealed a normal NT thickness of 1.8 mm. The subcutaneous nuchal fluid accumulation was no longer present at the following ultrasound scans. An amniocentesis was performed at 18 weeks' gestation.


RESULTS
Cytogenetic analysis revealed a karyotype of 46,XX,del(9)(q21.1q22.2). The parental karyotypes were normal. At 21 weeks' gestation, a 442-g female fetus was delivered with low-set ears, hypertelorism, and a thick nuchal fold. The parental origin of the interstitial deletion of 9q was analyzed with polymorphic DNA markers. With the microsatellite markers D9S238 (9q13), D9S889 (9q21.11), and D9S253 (9q22.2), two alleles inherited from the parents were seen in the proband, but with markers D9S1780 (9q21.31), D9S303 (9q21.32), D9S252 (9q21.33), and D9S316 (9q22.1), only one maternal allele was present. The deletion was of paternal origin.


CONCLUSIONS
Fetuses with uncommon aneuploidies may manifest increased NT in the first trimester. The present case provides evidence for a correlation between increased NT and interstitial 9q deletion. Prenatal identification of increased NT should alert subtle structural chromosome aberrations and prompt high-resolution karyotyping.
Chen
Chih-Ping
CP
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan, Republic of China. cpc_mmh@yahoo.com
Chern
Schu-Rern
SR
Chang
Tung-Yao
TY
Chen
Wen-Lin
WL
Chen
Li-Feng
LF
Wang
Wayseen
W
Cindy Chen
Hsiao-En
HE
D000328:Adult; D000782:Aneuploidy; D002899:Chromosomes, Human, Pair 9; D019465:Craniofacial Abnormalities / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000196:embryology / Q000235:genetics / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D017353:Gene Deletion; D005817:Genetic Counseling; D006801:Humans; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis