# Prader-Willi syndrome (PWS) gene-domain and AAV miniaturization for gene therapy

> **NIH NIH R21** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2024 · $196,579

## Abstract

A multisystem disorder, Prader Willi syndrome (PWS) is genetically complex with loss of function of a 2-3 Mb
domain of paternally-expressed imprinted genes. The polycistronic SNURF-SNRPN-snoRNA locus encoding 2
proteins and 5 snoRNAs, including SNORD116 as one major gene, is important in determining phenotype.
Treatment in PWS uses early clinical and molecular diagnosis with behavioral modification, growth hormone,
or ongoing drug trials that affect hyperphagia or behavior, but are limited by an incomplete understanding of
pleiotropic phenotypes. Although these measures improve outcomes, none are a cure and significant clinical
morbidity persists. Potential approaches for epigenetic or genetic therapy to reactivate or replace silent or
missing PWS-genes are complicated by heterochromatic silencing and the many genes involved in disease.
This project will test an innovative approach involving miniaturization of PWS genetic elements into a single
therapeutic adeno-associated virus (AAV)-vector. The new AAV vector series will assess feasibility to replace
80% of PWS-genes, helping to determine how and which gene losses lead to cellular and biochemical
phenotypes in PWS. Aim 1 tests the hypothesis that PWS-minigenes in an AAV-vector will appropriately
express PWS gene products in cells. The PWS-minigenes include SNURF-SNRPN in the endogenous
bicistronic layout with up to 5 snoRNAs, and the NDN-cistron, between AAV inverted terminal repeats. Use of
human gene sequences in rodent cells will distinguish expression of exogenous and endogenous loci.
Alternative vector structures will encode individual or clustered snoRNAs in SNURF-SNRPN introns or, to
mimic the endogenous organization, in 3’ introns. To reduce AAV vector size, and mimic endogenous
regulation, a synthetic NRF1-motif array mini-promoter having broad cell-specificity for expression will be used,
with all coding content of PWS-minigenes within AAV packaging capacity. Aim 2 tests the hypothesis that
AAV-minigenes can rescue PWS cellular phenotypes. A PWS β-cell (INS-1) model shows a cell-autonomous
defect in insulin secretion and deficits in RNA and protein production of multiple hormones and ER
chaperones, which derive from loss of one or more of the Snurf-Snrpn-snoRNA genes. AAV-PWS minigene
vectors packaged as serotype AAV6 (optimal for rodent endocrine cells) will be transduced into control and
PWS β-cell lines (3 each), assessing correction in levels of insulin secretion, mRNA and protein levels of
peptide hormones (e.g., insulins, IAPP) and ER chaperones (e.g., HSPA5, HSP90B1). Aim 3 (in vivo
translation) tests the hypothesis that AAV-minigenes can rescue the pancreatic islet phenotypes and neonatal
lethality of a mouse model lacking expression of all PWS-genes. Therapeutic outcomes of AAV injections in
utero vs. postnatal day 1 will be compared. Miniaturization of genetic components in a single AAV vector
represents a remarkable opportunity for in vivo gene therapy of not only PWS but m...

## Key facts

- **NIH application ID:** 10771280
- **Project number:** 5R21HD108695-02
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** Robert D Nicholls
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $196,579
- **Award type:** 5
- **Project period:** 2023-02-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10771280

## Citation

> US National Institutes of Health, RePORTER application 10771280, Prader-Willi syndrome (PWS) gene-domain and AAV miniaturization for gene therapy (5R21HD108695-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10771280. Licensed CC0.

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