A New Genetic Study on Pneumonia

A new genetic study identified five regions in the human genome associated with susceptibility to pneumonia, a leading cause of death worldwide.

Published in the journal Nature Communications, the study also found a surprising link between the risk of pneumonia and psychiatric conditions, such as schizophrenia, bipolar disorder and major depression.

There are several types of pneumonia, but the most common involve bacterial or viral infection in the lungs. The condition can be deadly for those most physically vulnerable, particularly the elderly and young children. Many of those hospitalized for COVID-19 also end up having to be treated for pneumonia.

Five Genetic Regions

This study, led by researchers at the University of Newcastle in Australia. It included data from more than half a million individuals and is believed to be the largest genomic study of pneumonia ever done. The research included data from 23andMe customers who consented to participate in research and data from the FinnGen consortium.

The researchers identified five genetic regions associated with pneumonia. Among those were some previously identified associations within human leukocyte antigen (HLA) genes. 

The HLA genes are the hundreds of genes on chromosome 6 that regulate the body’s immune system. The HLA gene also regulates the response to invading pathogens like viruses and bacteria. 

Role of Inflammation

The team also found three new associations in genes related to inflammation and immunity. They also found another new association in the gene MUC5AC. The gene is in a cluster of genes that regulate the production of mucin proteins in the body. Mucin proteins make up mucus, the substance that lubricates and protects the lining of the airways, digestive and reproductive system. The up-regulation of MUC5AC may exacerbate pneumonia by inducing inflammation in the airways.

According to the researchers, the link between the genetic risk for pneumonia and psychiatric conditions may be related to inflammation.

“I think it’s surprising, but in some ways, it’s not, as there are thought to be inflammatory risks for mental illness,” said Murray Cairns, one of the paper’s co-authors and a principal investigator at the University of Newcastle’s HMRI Precision Medicine Research Program. “(Inflammation) is a well-known risk factor for psychiatric illness, so it’s potentially a risk shared between those disorders.”

The researchers acknowledge that much more must be done to understand the link between pneumonia and mental illness. But within the paper, they hypothesize that the connection may be related to HLA genes and either their overresponse, inflammation, or inadequate response to an infection.

Understanding the role of this link with inflammation and the genetic associations for pneumonia could help researchers look for new treatments.

Find the full study in the journal Nature Communications.