Clinical Report: Investigation of Deletions in APC Promoter 1B Among Russian Families

Overview

This study investigates deletions in the APC promoter 1B among Russian families affected by familial adenomatous polyposis (FAP). The findings indicate no evidence of a founder effect in this population, with unique deletion boundaries identified in each patient. Whole-genome sequencing was performed on five unrelated patients with identified deletions.

Background

Familial adenomatous polyposis (FAP) is a hereditary cancer syndrome that leads to a high risk of colorectal cancer if untreated. The APC gene is crucial in this condition, with pathogenic variants being the primary cause. Understanding the genetic variations in different populations can aid in diagnosing and managing FAP effectively. The estimated incidence of FAP is around 1 in 10,000 live births, and germline pathogenic variants in the APC gene are found in 70 to 90 percent of patients.

Data Highlights

Deletions in the APC 1B promoter ranged from approximately 3 kbp to 122 kbp. Each deletion was unique, with no identical boundaries identified among patients.

Key Findings

• Deletions in the APC 1B promoter ranged from approximately 3 kbp to 122 kbp.
• No correlation was found between deletion size and age of onset or disease severity.
• Each deletion was unique, with no identical boundaries identified among patients.
• Four patients had right deletion breakpoints located within a 1 kbp region downstream from the 1B promoter.
• No evidence of a founder effect was observed in the Russian population studied.

Clinical Implications

Accurate identification of deletion breakpoints can aid in genetic counseling and management strategies for affected families.

Conclusion

The investigation into APC promoter 1B deletions in Russian families with FAP reveals unique genetic alterations without a founder effect.

Related Resources & Content

1. Author(s)/Org, Source, Year -- Title
2. the new gastroenterologist, News Gastro, 2026 -- APC mosaicism may explain unresolved polyposis cases
3. Frontiers in Oncology, Frontiers in Oncology, 2026 -- Case Study: Identification of BMPR1A and BARD1 Variants in a Colombian Family Affected by Juvenile Polyposis Syndrome
4. the pathologist, The Pathologist, 2026 -- The Tumor Test That Solves Polyposis
5. ICARE Social Media Post, Inherited Cancer Registry (ICARE), 2026 -- NCCN Colorectal, Endometrial, Esophageal, and Gastric Cancer Guidelines (V1.2026)
6. Polymorphisms in the ABCB1/MDR1 Gene as Predictive Indicators in Colorectal Cancer Outcomes
7. APC-Associated Polyposis Conditions
8. ICARE Social Media Post June 2026 NCCN Colorectal, Endometrial, Esophageal, and Gastric Cancer Guidelines (V1.2026) – Inherited Cancer Registry (ICARE)
9. The Effect of Celecoxib, a Cyclooxygenase-2 Inhibitor, in Familial Adenomatous Polyposis | New England Journal of Medicine