# Rare variants associated with AVSD in Down Syndrome > **NIH NIH F31** · EMORY UNIVERSITY · 2024 · $48,974 ## Abstract PROJECT SUMMARY Congenital Heart Defects (CHDs) are the most prevalent structural birth defect, affecting 8-10 of every 1000 live births and accounting for 25% of infant mortality. Infants born with a CHD often undergo many corrective surgeries, which aim to restore normal cardiac function. Consequently, they spend much of their early-life in the hospital, causing a large physical, emotional, and financial burden. These interventions, however, remain restorative not curative, and infants with a CHD who survive into adulthood remain at risk for other comorbidities that are associated with a “sick heart”. Understanding the pathways that are important for CHD pathogenesis and normal heart development through genetic analyses would aid in the treatment/prevention of these defects. One severe form of CHD that is of particular interest is the atrioventricular septal defect (AVSD). AVSD is rare in the general population, affecting 1 in 10,000 euploid infants. By contrast, AVSD affects 1 in 5 triploid infants in the Down Syndrome (DS) population. The 2000-fold increase in AVSD risk in DS suggests that dosage of chromosome 21 is a principal risk factor for AVSD. However, since half of the infants born with DS have a structurally normal heart, the extra copy of chromosome 21 alone is insufficient to cause AVSD, suggesting that there may be other factors that modify this risk. Previous genome wide association studies (GWAS) of AVSD in DS have established that common variants with large effect size do not fully explain the increased risk in AVSD among DS. In addition, candidate gene studies based on genes implicated in CHDs have identified rare variants associated with AVSD in DS, supporting a role for rare variants throughout the genome on AVSD pathogenesis and justifying the use of whole genome sequencing (WGS) to increase discovery potential. Taken together, the previous studies of AVSD in a sensitized DS population lead us to hypothesize that there is an increased burden of rare variants that are incompletely penetrant on an euploid background which modify AVSD risk on a trisomy 21 background. This hypothesis will be tested in three independent but complementary aims in which we will leverage WGS of individuals with CHD and DS, normal hearts and DS, and their euploid parents with structurally normal hearts, and euploid individuals with CHD to: 1) identify rare variants with and without dosage effects on chromosome 21 and 2) identify rare and de novo variants in the genome outside of chromosome 21 and 3) determine the role of AVSD risk variants found in DS to euploid AVSD and other subtypes of CHD in DS. Our long-term goal is to reduce the clinical burden associated with AVSD by identifying pathways that are vulnerable to genetic changes and consequently open the possibility of modifiable targets to aid in the prevention and treatment of AVSD. Notably, previous studies suggest that risk factors identified in the DS population are relevant to the chromosom... ## Key facts - **NIH application ID:** 10900433 - **Project number:** 1F31HL168878-01A1 - **Recipient organization:** EMORY UNIVERSITY - **Principal Investigator:** ELIZABETH FELDMAN - **Activity code:** F31 (R01, R21, SBIR, etc.) - **Funding institute:** NIH - **Fiscal year:** 2024 - **Award amount:** $48,974 - **Award type:** 1 - **Project period:** 2024-09-13 → 2027-09-12 ## Primary source NIH RePORTER: https://reporter.nih.gov/project-details/10900433 ## Citation > US National Institutes of Health, RePORTER application 10900433, Rare variants associated with AVSD in Down Syndrome (1F31HL168878-01A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10900433. Licensed CC0. --- *[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*