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CDH1 Missense Variant c . 1679C > G (p.T560R) Completely Disrupts Normal Splicing through Creation of a Novel 5 ’ Splice Site

View Article: PubMed Central - PubMed

ABSTRACT

Disease-causing germline mutations in CDH1 cause Hereditary Diffuse Gastric Cancer (HDGC). For patients who meet the HDGC screening criteria, the identification and classification of the sequence variants found in CDH1 are critical for risk management of patients. In this report, we describe a germline CDH1 c.1679C>G (p.T560R) variant identified in a 50 year old man who was diagnosed with gastric cancer with a strong family history of gastric cancer (one living brother was diagnosed with gastric cancer at 63 and another brother died of gastric cancer at 45). cDNA analysis, involving fragment analysis and cloning, indicated that the p.T560R mutation created a novel 5’ splice donor site, which led to a novel transcript with a 32 nucleotide deletion in exon 11. This abnormal transcript putatively produces a truncated CDH1 protein (E-cadherin) of 575 amino acids instead of 882. We also demonstrated that the variant completely abolishes normal splicing as the mutant allele does not generate any normal transcript. Furthermore, the CDH1 c.1679C>G (p.T560R) variant segregated with gastric cancer in all three family members affected with gastric cancer in this family. These results support the conclusion that CDH1 c.1679C>G (p.T560R) variant is a pathogenic mutation and contributes to HDGC through disruption of normal splicing.

No MeSH data available.


Related in: MedlinePlus

Patient pedigree, CDH1 mutation and H&E image of diffuse gastric cancer.(A) The patient (indicated with the arrow head) is a 50 year old man who was diagnosed with gastric cancer at the age of 50. In his generation, three members were diagnosed with gastric cancers (one brother died of gastric cancer at 45, another brother was diagnosed with gastric cancer at 63). All three brothers affected with gastric cancer were determined to have the CDH1 c.1679 C>G p.T560R variant. (B) our patient’s germline CDH1 sequencing demonstrating the CDH1 c.1679C>G variant. (C) Haematoxylin and eosin stain (H&E stain) of patient’s biopsy specimen showing infiltrating adenocarcinoma poorly differentiated with mucinous and signet ring cell features. The signet ring cells are characteristic of hereditary diffuse gastric cancer (HDGC). They contain large amount of mucin which pushes the nucleus to the cell periphery (see arrows).
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pone.0165654.g001: Patient pedigree, CDH1 mutation and H&E image of diffuse gastric cancer.(A) The patient (indicated with the arrow head) is a 50 year old man who was diagnosed with gastric cancer at the age of 50. In his generation, three members were diagnosed with gastric cancers (one brother died of gastric cancer at 45, another brother was diagnosed with gastric cancer at 63). All three brothers affected with gastric cancer were determined to have the CDH1 c.1679 C>G p.T560R variant. (B) our patient’s germline CDH1 sequencing demonstrating the CDH1 c.1679C>G variant. (C) Haematoxylin and eosin stain (H&E stain) of patient’s biopsy specimen showing infiltrating adenocarcinoma poorly differentiated with mucinous and signet ring cell features. The signet ring cells are characteristic of hereditary diffuse gastric cancer (HDGC). They contain large amount of mucin which pushes the nucleus to the cell periphery (see arrows).

Mentions: We report on a 50 year old man of Indian descent who was diagnosed with gastric cancer at age of 50. In his generation, three members including the proband were diagnosed with gastric cancer (one brother died of gastric cancer at 45, another brother was diagnosed with gastric cancer at 63) (Fig 1A). The CDH1 c.1679C>G (p.T560R) was identified in the patient through CDH1 full gene sequencing analysis at the Diagnostic Molecular Genetics Laboratory at Memorial Sloan-Kettering Cancer Center (MSKCC). The brother affected with gastric cancer at 63 was identified to carry the same CDH1 variant through testing in a reference lab, which was initially classified as a variant of uncertain significance. Patient’s father had a reported history of gastric ulcers.


CDH1 Missense Variant c . 1679C > G (p.T560R) Completely Disrupts Normal Splicing through Creation of a Novel 5 ’ Splice Site
Patient pedigree, CDH1 mutation and H&E image of diffuse gastric cancer.(A) The patient (indicated with the arrow head) is a 50 year old man who was diagnosed with gastric cancer at the age of 50. In his generation, three members were diagnosed with gastric cancers (one brother died of gastric cancer at 45, another brother was diagnosed with gastric cancer at 63). All three brothers affected with gastric cancer were determined to have the CDH1 c.1679 C>G p.T560R variant. (B) our patient’s germline CDH1 sequencing demonstrating the CDH1 c.1679C>G variant. (C) Haematoxylin and eosin stain (H&E stain) of patient’s biopsy specimen showing infiltrating adenocarcinoma poorly differentiated with mucinous and signet ring cell features. The signet ring cells are characteristic of hereditary diffuse gastric cancer (HDGC). They contain large amount of mucin which pushes the nucleus to the cell periphery (see arrows).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5120775&req=5

pone.0165654.g001: Patient pedigree, CDH1 mutation and H&E image of diffuse gastric cancer.(A) The patient (indicated with the arrow head) is a 50 year old man who was diagnosed with gastric cancer at the age of 50. In his generation, three members were diagnosed with gastric cancers (one brother died of gastric cancer at 45, another brother was diagnosed with gastric cancer at 63). All three brothers affected with gastric cancer were determined to have the CDH1 c.1679 C>G p.T560R variant. (B) our patient’s germline CDH1 sequencing demonstrating the CDH1 c.1679C>G variant. (C) Haematoxylin and eosin stain (H&E stain) of patient’s biopsy specimen showing infiltrating adenocarcinoma poorly differentiated with mucinous and signet ring cell features. The signet ring cells are characteristic of hereditary diffuse gastric cancer (HDGC). They contain large amount of mucin which pushes the nucleus to the cell periphery (see arrows).
Mentions: We report on a 50 year old man of Indian descent who was diagnosed with gastric cancer at age of 50. In his generation, three members including the proband were diagnosed with gastric cancer (one brother died of gastric cancer at 45, another brother was diagnosed with gastric cancer at 63) (Fig 1A). The CDH1 c.1679C>G (p.T560R) was identified in the patient through CDH1 full gene sequencing analysis at the Diagnostic Molecular Genetics Laboratory at Memorial Sloan-Kettering Cancer Center (MSKCC). The brother affected with gastric cancer at 63 was identified to carry the same CDH1 variant through testing in a reference lab, which was initially classified as a variant of uncertain significance. Patient’s father had a reported history of gastric ulcers.

View Article: PubMed Central - PubMed

ABSTRACT

Disease-causing germline mutations in CDH1 cause Hereditary Diffuse Gastric Cancer (HDGC). For patients who meet the HDGC screening criteria, the identification and classification of the sequence variants found in CDH1 are critical for risk management of patients. In this report, we describe a germline CDH1 c.1679C>G (p.T560R) variant identified in a 50 year old man who was diagnosed with gastric cancer with a strong family history of gastric cancer (one living brother was diagnosed with gastric cancer at 63 and another brother died of gastric cancer at 45). cDNA analysis, involving fragment analysis and cloning, indicated that the p.T560R mutation created a novel 5’ splice donor site, which led to a novel transcript with a 32 nucleotide deletion in exon 11. This abnormal transcript putatively produces a truncated CDH1 protein (E-cadherin) of 575 amino acids instead of 882. We also demonstrated that the variant completely abolishes normal splicing as the mutant allele does not generate any normal transcript. Furthermore, the CDH1 c.1679C>G (p.T560R) variant segregated with gastric cancer in all three family members affected with gastric cancer in this family. These results support the conclusion that CDH1 c.1679C>G (p.T560R) variant is a pathogenic mutation and contributes to HDGC through disruption of normal splicing.

No MeSH data available.


Related in: MedlinePlus