# Cellular phenotype of mucopolysaccharidosis II for studies of genomic variants

> **NIH NIH R03** · WASHINGTON UNIVERSITY · 2022 · $78,750

## Abstract

ABSTRACT
The diagnosis of mucopolysaccharidosis type II (MPS II, also known as Hunter syndrome) by newborn
screening is principally made by dried blood spot assay for the iduronate-2-sulfatase enzyme, followed by
assessment of glycosaminoglycans and molecular testing for the IDS gene located on the X chromosome.
However, diagnosis is complicated by the difficulty in interpreting molecular diagnostic testing results due to
the large number of variants of uncertain significance in the IDS gene. Furthermore, we do not have a thorough
understanding of the pseudodeficiency alleles, which are defined by an apparent deficiency of a protein that
does not cause disease. While the pseudodeficiency of an enzyme like iduronate-2-sulfatase shows low
activity against an artificial substrate, it results in normal catabolism of the natural substrate. Here, we propose
to develop high-throughput, cell-based assays and analysis methods to support the comprehensive functional
assessment of IDS gene variants. The core hypothesis outlined in this proposal is that experimental data
measuring the direct functional effects of variants will inform accurate disease risk prediction. In addition, we
hypothesize that an in vitro, cell-based assay will more accurately detect abnormal processing of the natural
substrate predictive of disease than assays using artificial substrates. Here, we will develop a functional assay
in human A549 cells with known pathogenic and benign variants generated using CRISPR/Cas9. These will be
studied on the CellRaft Technology platform in the Buchser laboratory, which uses machine learning to
determine the combination of morphological phenotypes that define pathogenicity. A cellular phenotype will be
established and then tested using a second set of variants combined with rescue experiments. The results will
inform variant classification in IDS molecular testing and improve diagnosis of individuals including those
identified by low iduronate-2-sulfatase activity on newborn screening.

## Key facts

- **NIH application ID:** 10442244
- **Project number:** 1R03NS127256-01
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** William J Buchser
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $78,750
- **Award type:** 1
- **Project period:** 2022-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10442244

## Citation

> US National Institutes of Health, RePORTER application 10442244, Cellular phenotype of mucopolysaccharidosis II for studies of genomic variants (1R03NS127256-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10442244. Licensed CC0.

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