了解しました！ご指定の内容をもとに、英語版のブログ記事を作成しました。

Title: Do Only Japanese People Have It? The Mystery of the ALDH2 Gene

Introduction

Did you know that around 40% of Japanese people carry a unique genetic trait that affects how their bodies process alcohol? This genetic variant, known as the inactive form of the ALDH2 gene, is often associated with the well-known “Asian flush.” But beyond facial redness, this gene holds fascinating clues about human evolution and health risks.

What is the ALDH2 Gene?

The ALDH2 gene (Aldehyde Dehydrogenase 2) is responsible for breaking down acetaldehyde, a toxic byproduct produced when the body metabolizes alcohol.

In people with a normal ALDH2 gene, acetaldehyde is quickly broken down into harmless substances.
In those with the inactive version, the breakdown process is slower, causing acetaldehyde to accumulate.

This buildup leads to symptoms such as facial flushing, nausea, and rapid heartbeat after drinking alcohol.

How Common is This Gene Variant?

About 40% of Japanese people have the inactive ALDH2 variant.
It is also common among other East Asians, including Chinese and Koreans.
In contrast, the variant is extremely rare in populations outside East Asia.

This unique distribution raises the question: Why did this genetic trait persist in East Asia but not elsewhere?

The Evolutionary Mystery

Researchers suggest that the inactive ALDH2 gene may have provided evolutionary advantages in ancient times. Some theories include:

Protection against alcohol overconsumption – People with the inactive gene naturally drink less, which may have prevented health issues.
Defense against parasites and pathogens – Acetaldehyde buildup may have offered resistance to certain infections.
Dietary and environmental influences – The gene may have been favored by specific lifestyles in East Asia.

While the exact reason is still debated, it is clear that the gene persisted due to some survival benefit.

Health Implications Today

While it may have been advantageous in the past, today the inactive ALDH2 gene can pose health risks:

Increased cancer risk – Especially esophageal cancer, due to acetaldehyde buildup.
Heart disease – Studies suggest a link between the inactive gene and cardiovascular problems.
Lower alcohol tolerance – Which can affect social habits and lifestyle.

Doctors often recommend that people with the inactive ALDH2 gene limit alcohol consumption to reduce health risks.

Conclusion

The ALDH2 gene is more than just a quirk of alcohol tolerance—it is a window into human evolution and health. For Japanese people, and many East Asians, this genetic trait is both a biological mystery and a reminder of how our genes continue to shape our lives today.

So next time you see someone with the “Asian flush,” remember: it’s not just about drinking—it’s about history, survival, and science.