Prevalence of Major Aneuploidy Markers for Down Syndrome in the Hispanic Population
Capstone Project Committee: Ngina Conners, MD, Daragh Conrad, MS, CGC, Sonja Eubanks, MS, CGC, Sat Gupta, PhD (Statistical Consultant), Christy Stanley, MS, CGC
In recent years, absent/hypoplastic fetal nasal bone has been shown to be an important marker for fetal aneuploidy in Caucasian, Asian and African-American patients. However, few studies have focused on the significance of this marker for aneuploidy in the Hispanic population. Additionally, few studies have looked at the effects of ethnicity on nuchal fold size and aneuploidy risk assessment. Anecdotal reports indicated that both of these markers appear to be associated with a lower risk for aneuploidy in Hispanic patients than what is currently reported in the literature for other ethnicities. This study was used to help to determine the significance of absent/hypoplastic nasal bone and increased nuchal fold as predictors of chromosome abnormalities in the local Hispanic population. This is a retrospective chart review of women undergoing an anatomy ultrasound for various indications (advanced maternal age, abnormal maternal serum screening, and routine dating/anatomy scan), during the second trimester of pregnancy. The fetal nasal bone and nuchal fold size for each fetus was reviewed from an ultrasound database, ASOBGYN, and by chart review at the Comprehensive Fetal Care Center of Wake Forest University Baptist Medical Center for all Hispanic fetuses seen from June 1, 2006-September 30. 2002 Hispanic patients were found, and 17 (0.85%) of these patients had increased nuchal fold or hypoplastic/absent nasal bone. 5 of 17 (29%) had hypoplastic or absent nasal bone and 12 of 17 (71%) had increased nuchal fold. Of these, 0 out of 13 (0%) patients showed physical features of Down syndrome at birth and 12 out of 13 (92%) had a normal newborn exam. Only one patient of the 13 (7.6%) eligible participants had an abnormal newborn exam. Three participants were lost to follow up and one patient had a termination of pregnancy due to multiple anomalies. This information can be used to determine accurate likelihood ratios for the Hispanic population regarding these markers and help genetic professionals give appropriate risk assessments to families.
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