217 WITHDRAWN

218 Does fetal gender play a role in thedetection of fetal microchimerism?Kimberly Ma1, J. Nelson2, V. Gadi3, Hilary Gammill11University of Washington, Obstetrics and Gynecology, Seattle, WA,2University of Washington, Rheumatology, Seattle, WA, 3University ofWashington, Medical Oncology, Seattle, WAOBJECTIVE: The protective association between parity and breast can-cer appears to be stronger in women with sons compared to daugh-ters. The underlying mechanism is unknown and has been hypothe-sized to be immunologic or endocrinologic. During pregnancy,transplacental cellular exchange results in microchimerism (Mc). Mccan persist and is associated with protection from breast cancer. Wesought to evaluate whether fetal Mc concentration varies according tofetal gender, thereby potentially contributing to the differential pro-tection of parity with sons versus daughters.STUDY DESIGN: Pregnant women and parous, nonpregnant womenwere studied. Blood samples were obtained, and DNA was extractedfrom Ficoll-purified peripheral blood mononuclear cells. Maternaland fetal HLA genotyping was conducted, and fetal Mc was quantifiedemploying a panel of Q-PCR assays targeting fetal-specific HLA al-leles. Detection of fetal Mc was compared according to fetal gender.Among the pregnant women, current fetal gender was used to definemale versus female exposure. Prior birth of any male child was con-sidered male exposure in nonpregnant, parous women.RESULTS: 97 subjects were studied, 35 during pregnancy and 62 out-side of pregnancy. There were no differences in the detection of fetalMc according to fetal gender. In pregnant women, 6.7% (1/15) ofwomen with a male fetus had fetal Mc detected compared to 10.0%(2/20) with a female fetus (p�0.73). Outside of pregnancy, fetal Mcwas detected in 18.9% (7/37) of those with a history of a male fetuscompared to 20.0% (5/25) of those with only a female fetus (p�0.92).CONCLUSION: We observed no association of fetal gender with detec-tion rates of fetal Mc during pregnancy or in parous women. It ispossible that fetal Mc may contribute to known epidemiological find-ings of differential protection of parity for diseases according to off-spring gender. However, our findings suggest that if this is the case,functional, rather than quantitative differences in Mc by fetal genderare more likely to underlie a relationship.

219 Profiling of microRNA by next-gen deepsequencing reveals novel and modifiablemiRNA species in human breast milkKjersti Aagaard1, Erika Munch1, R. Alan Harris3, MahmoudMohammad2, Ashley Benham6, Sasha Pejerrey4, PreethiGunaratne5, Morey Haymond2

1Baylor College of Medicine, Maternal-Fetal Medicine, Houston, TX, 2BaylorCollege of Medicine, Pediatrics, Houston, TX, 3Baylor College of Medicine,Molecular and Human Genetics, Bioinformatics Research Lab, Houston, TX,4Baylor College of Medicine, Molecular and Cell Biology, Houston, TX,5Baylor College of Medicine, Pathology, Houston, TX, 6University ofHouston, Biology and Biochemistry, Houston, TXOBJECTIVE: While breast milk has unique health advantages for infants, themechanisms by which it regulates the physiology of newborns are incom-pletely understood. microRNAs (miRNAs), a class of noncoding RNAs, arecritical transcellularmediatorsofposttranscriptionalgeneregulation.Wehy-pothesized that breast milk in general, and milk fat globules in particular,contain significant numbers of known and limited novel miRNA species de-tectable with massively parallel sequencing.STUDY DESIGN: Extracted RNA from 3 well-characterized cohorts of lac-tating women (before and after rhGH, high glucose vs galactose dietmodified, or high fat vs high carbohydrate diet modified; Figure panel A)was smRNA-enriched. smRNA was subjected to massively parallel shot-gun sequencing, and robustly analyzed on customized pipelines to iden-tify functional targets. Data were validated with qPCR.RESULTS: smRNA-Seq was performed to generate 124,110,646 36-ntreads, including 308 of 1018 (29%) known mature miRNAs (miRBase16.0). We identified 21 putative novel miRNAs, of which 12 werevalidated. Collectively, these miRNAs target 9074 genes; the 10 mostabundant of these predicted to target 2691 genes with enrichment fortranscriptional regulation of metabolic and immune responses (pan-els B&C). Moreover, expression of several novel miRNAs were signif-icantly and specifically altered following maternal high-fat diet mod-ifications (p�0.05).CONCLUSION: We have shown for the first time that novel (and known)miRNAs are enriched in breast milk, and expression of several novelmiRNA species is regulated by a high fat maternal diet. Based onrobust pathway mapping, our data supports the notion that thesematernally secreted miRNAs-which are stable in the milk fat globules-play a regulatory role in the infant and account in part for the healthbenefits of breast milk. We speculate that regulation of these miRNAby a high fat maternal diet enables modulation of fetal metabolism toaccommodate significant dietary challenges.

*Data expressed as medians and interquartile ranges.

Identification and functional analysis ofnovel miRNA in human breast milk

www.AJOG.org Clinical Obstetrics, Epidemiology, Fetus, Medical-Surgical Complications, Neonatology, Physiology/Endocrinology, Prematurity Poster Session I

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