3D Genome Mapping of Rare Immune Cells Reveals New Crohn’s Disease Genes

Our genetic material is rarely a simple, flat line. Inside human cells, two meters of DNA scrunch tightly together, folding in three dimensions to bring distant regulatory regions into direct physical contact with the genes they govern. While geneticists have long known that this architecture dictates cellular behavior, observing it inside rare, specialized tissues has historically presented a formidable technical barrier. Conventional methods for mapping spatial genome organization required millions of cells as input, restricting analyses to abundant populations circulating in the blood.

A research team overcame that roadblock by deploying a miniaturized version of Capture Hi-C, an approach that maps long-range DNA interactions using far fewer cells than conventional methods require. The study, co-led by researchers at the MRC Laboratory of Medical Sciences in London alongside a global consortium, zeroes in on type 3 innate lymphoid cells, known as ILC3s. These tissue-resident immune cells patrol barrier surfaces like the gut, regulating inflammation and repairing tissue damage.

Mapping the 3D Genome in Human ILC3s

Because ILC3s are scarce and fail to replicate easily outside the body, studying their regulatory genome architecture required specialized tools. The miniaturized Capture Hi-C protocol used in the study was developed by Prof. Valeriya Malysheva during her postdoctoral work at the MRC Laboratory of Medical Sciences in the UK before her current role as a group leader at the VIB-UAntwerp Center for Molecular Neurology.

When applied to human tonsil-derived ILC3s, the protocol captured chromosomal contacts at both single-fragment resolution and through a five-kilobase binning strategy. This dual approach allowed investigators to spot distal enhancers acting over long chromosomal distances to regulate gene activity.

By intersecting these 3D maps with data from large-scale genome-wide association studies, the team prioritized more than 100 genes in ILC3s likely influenced by enhancer variants associated with Crohn’s disease risk. While roughly half of those genes were already familiar players in inflammatory bowel disease, the remainder had never been linked to the condition before.

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An Unexpected Link to Batten Disease Gene CLN3

The most surprising discovery to emerge from the global mapping effort involved a gene best known for its role in a devastating rare pediatric condition. Mutations in CLN3 cause Batten disease, a fatal neurodegenerative disorder. Researchers had little reason to suspect the gene played a direct part in regulating peripheral immune responses.

To test the functional relevance of this connection, the team conducted follow-up experiments. They observed that this gene directly influences how strongly the cells produce inflammatory signals. According to the researchers, the finding demonstrates how the genome is wired to uncover unexpected connections, including those between the nervous and immune systems.

Unlocking Genetic Risk Across Rare Cell Types

For decades, researchers studying polygenic conditions like inflammatory bowel disease faced a frustrating bottleneck. Without knowing which gene an enhancer actually touches, translating genetic risk into therapeutic targets remained guesswork.

Until now, the requirement for millions of cells meant scientists could only study abundant circulating blood cells rather than the specialized immune populations most relevant to barrier diseases.

By combining high-resolution spatial mapping with specialized analytical frameworks, the consortium has established a blueprint for examining other rare immune populations. As investigators continue to clarify how genes like CLN3 shape inflammatory signals, the methodology opens a direct path toward interpreting the functional consequences of inherited risk in human autoimmune disease.