Scientists identified a key breakpoint in the RELA gene that helps predict how harmful mutations cause a rare inherited inflammatory disease. Mutations in a location before amino acid P290 reduce protein levels, while those located after P290 produce disruptive proteins. The finding could improve diagnosis and treatment selection for patients with RELA deficiency.
Image Credit: Hiroko Hayakawa/Hiroshima University
Scientific Frontline: Extended "At a Glance" Summary: The RELA Gene Boundary Discovery
The Core Concept: Researchers have identified a critical structural boundary within the immune-regulating gene RELA—specifically at amino acid proline 290 (P290)—that dictates how genetic mutations manifest in patients with a rare inherited inflammatory disease.
Key Distinction/Mechanism: Mutations occurring before the P290 boundary result in haploinsufficiency (a harmful shortage of functional protein). Conversely, mutations occurring after P290 cause a dominant-negative effect, where an abnormal, shortened protein actively interferes with normal cellular function and triggers more severe inflammation.
Major Frameworks/Components:
- Autosomal Dominant RELA Deficiency: A rare genetic condition characterized by recurrent ulcers, intestinal inflammation, and broader autoinflammatory symptoms.
- Haploinsufficiency vs. Dominant-Negative Effect: The two distinct pathological pathways determined by the genetic mutation's physical location relative to the P290 breakpoint.
- Stop Codons: Premature nucleotide sequences that terminate protein synthesis, driving the specific type of molecular failure depending on where they occur.
Branch of Science: Molecular Genetics, Immunology, and Clinical Pathology.
Future Application: This functional indicator allows clinicians to quickly interpret newly discovered RELA mutations and rapidly select appropriate clinical interventions, such as utilizing biologic therapies (e.g., anti-TNF drugs) instead of standard corticosteroids for patients with dominant-negative variants.
Why It Matters: By establishing a predictable genetic breakpoint, medical professionals can significantly reduce trial-and-error prescribing, thereby personalizing and accelerating critical care for patients suffering from this rare and severe inflammatory disorder.
Not all broken genes fail in the same way: some simply stop working, while others interfere with what still works.
Researchers from Hiroshima University have identified a critical boundary within the immune-regulating gene called RELA that helps predict how harmful mutations cause disease. Their findings could improve diagnosis and treatment for patients with a rare inherited inflammatory disease.
The RELA gene produces a protein that plays an important role in immune responses, cell survival, and inflammation. Mutations in one copy of the RELA gene can cause a condition known as autosomal dominant RELA deficiency. Patients may develop recurring mouth and genital ulcers, intestinal inflammation, and, in some cases, broader autoinflammatory symptoms. Thus far, only 45 people from 17 families have been confirmed to have this deficiency worldwide.
“In autosomal dominant RELA deficiency, clinical manifestations differ depending on the nature of the variant,” said Satoshi Okada, professor at Hiroshima University’s Graduate School of Biomedical and Health Sciences and corresponding author of the study.
Some mutations lead to haploinsufficiency, in which the body does not produce enough functional protein. Others cause a dominant-negative effect, in which the abnormal protein interferes with the normal one.
Seeking a way to accurately predict which type of mutation is responsible for which effect, the team studied eight patients from five families with autosomal dominant RELA deficiency. Their results identified the amino acid proline at position 290 (P290) as a key dividing line in the RELA protein.
“RELA variants with a stop codon located N-terminal to amino acid P290 exhibit haploinsufficiency, whereas RELA variants with a stop codon located C-terminal to P290 exhibit a dominant-negative effect,” Okada said.
A stop codon is a nucleotide sequence in mRNA that, just like a period at the end of a sentence, signals the cell to terminate protein synthesis. If the stop codon occurs early, before P290 (or near the protein’s N-terminal end), the faulty gene copy often cannot produce a usable protein, leaving only one functional copy and causing a shortage of RELA protein. If the stop codon occurs later, after P290 (or near the C-terminal end), the cell may produce a shortened protein that interferes with the normal one and can trigger more severe inflammation.
Understanding the distinction could have direct clinical value. Patients carrying dominant-negative variants responded less well to corticosteroids and more often required biologic therapies, particularly anti-tumor necrosis factor (anti-TNF) drugs.
“Our findings offer an indicator that could help clinicians interpret newly discovered RELA mutations more quickly and therefore choose more appropriate treatments earlier in the disease course,” Okada said.
However, not all variants are easy to classify. Missense mutations, which alter a single amino acid rather than creating an early stop signal, still require laboratory testing since their effects cannot be predicted from location alone.
“Reliably determining the functional impact of RELA missense variants remains an unmet challenge and an important priority for future research,” Okada said.
Funding: This study was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI, the Japan Agency for Medical Research and Development (AMED), the Program for Accelerating Medical Research HK2-MIRAI, and the Program for Forming Japan’s Peak Research Universities (J-PEAKS).
Published in journal: Journal of Allergy and Clinical Immunology
Title: Discovering patterns in the pathologic significance of non-missense deleterious variants in RELA
Authors: Hiroko Hayakawa, Miyuki Tsumura, Takanori Utsumi, Hiroshi Nihira, Wei-Te Lei, Ryo Ogino, Giorgia Bucciol, Tomohiro Nakano, Kiyoko Amo, Kunihiko Moriya, Seiichi Hayakawa, Yoko Mizoguchi, Shuhei Karakawa, You-Ning Lin, Han-Po Shih, Chia-Chi Lo, Sunita Janssenswillen, Sien Van Loo, Djalila Mekahli, Dusan Bogunovic, Stephanie Boisson-Dupuis, Kazushi Izawa, Cheng-Lung Ku, Takahiro Yasumi, Takaki Asano, Isabelle Meyts, and Satoshi Okada
Source/Credit: Hiroshima University
Edited by: Scientific Frontline
Reference Number: imgy052226_01