Genomic Tool for Mesothelioma Diagnosis Could Be Coming

New research suggests that a gene segment tends to go missing much more often in pleural mesothelioma cases than in those involving peritoneal mesothelioma.

This discovery will be helpful to doctors who want to give you a faster, surer mesothelioma diagnosis.

The research also suggests that gene deletions can be useful in quickly telling whether fluid building up in your chest is the result of a benign mesothelial proliferation or of malignant mesothelioma.

This research, published in the Journal of Clinical Pathology, also adds to evidence of genetic predisposition to mesothelioma.

If genetic predisposition is proven correct, researchers may be able to devise mesothelioma diagnostic tools that are even more reliable. And perhaps even tools that can accurately predict mesothelioma onset.

Mesothelioma Tissues Examined

To gain their insights, the researchers performed fluorescence in situ hybridization (FISH) analysis on tissues from 54 cases of malignant mesothelioma.

Forty of the samples came from patients with pleural mesothelioma and the remaining 14 came from patients with peritoneal mesothelioma.

The tissues, embedded in wax, were examined under the microscope for gene abnormalities. When detected, the type, location and frequency of each abnormality was noted.

The researchers found that gene material was missing at a particular location along a particular chromosome in 34 out of the 40 pleural mesothelioma samples — 85 percent of the total.

Meanwhile, at the same chromosome location in the peritoneal mesothelioma samples, this gene material was missing in only 36 percent of them.

The location in question was 9p21.

The numbers and letter in 9p21 serve as a map coordinate. The 9 identifies the ninth of the 43 chromosomes found in every human cell.

The rough equivalent on a conventional street map would be a street named Ninth Avenue.

The letter “p” in 9p21 identifies the shortest of the several pieces into which chromosome Number 9 divides.

Going back to the street map analogy, the “p” would be like the designation “north” or “south” that precedes the name of the avenue.

The number 21 refers to a defined segment within the “p” segment. On a street map, 21 would be the address of a particular house on North Ninth Avenue.

Here, however, 9p21 refers to a gene address that’s not there. It’s supposed to be there, but it’s not.

It would be as if you were going to visit a friend who told you he lived at 21 North Ninth Avenue, but all you can find when you get there are 19 North Ninth and 23 North Ninth.

Genomic Basis Of Mesothelioma

In genetics, when you have a missing chromosomal segment — a deletion, they call it —you have the basis for potentially serious disease.

The researchers who conducted this study saw a few other gene deletions in addition to the one at position 9p21. The others were 1p36, 22q12, and 14q32.

On top of that, they also noticed three gene amplifications.

Amplification of a gene site is like having a home at a specific street address where it’s zoned for one-story dwellings but the owner has remodeled and added an unpermitted second story.

The amplified genes were at 5p15, 7p12, and 8q24.

The significance of the amplifications was that they occurred much more often in the peritoneal mesothelioma tissues than in those of the pleural mesothelioma variety.

“Our study suggests that the pathway of the genetic abnormality might vary between pleural and peritoneal malignant mesothelioma,” the researchers wrote.