Scientists report that the effective population of the critically endangered Amur tiger is less than 14 animals.
About 500 Amur tigers have survived in the wild, but the effective population is a measure of the genetic diversity of the world's largest cat, according to BBC's Victoria Gill.
Low diversity means they are more vulnerable to disease or rare genetic disorders.
These results paint a grim picture for the tiger's chance of survival.
The findings are reported in the journal Mammalian Biology.
The Amur tiger once lived across a large portion of northern China, the Korean peninsula, and the southernmost regions of eastern Russia.
The tiger was almost driven to extinction during the early 20th Century as expanding human settlements, habitat loss and poaching wiped out this biggest of cats from over 90 percent of its range.
The new study identified that this recent "genetic bottleneck" has decimated the Amur tiger gene pool.
A more genetically diverse population of animals has a much better chance of survival, which is more likely to contain the genetic resistance to a variety of diseases and is less likely to succumb to rare genetic disorders.
Scientists in Russia, Spain and Germany worked together to analyze DNA samples from 15 wild Amur tigers in the Russian Far East.
They took blood samples from the animals and screened them for certain "markers."
The results revealed evidence of the genetic bottleneck during the animals' recent history, when the variety of genes that are passed on is dramatically reduced.
The Amur tiger's genetics have not recovered from this.
"Our results are the first to demonstrate a quite recent genetic bottleneck in Siberian tigers, a result that matches the well-documented severe demographic decline of the Siberian tiger population in the 1940s," the researchers wrote in the paper.
"The worryingly low effective population size challenges the optimism for the recovery of the huge Siberian cat."
The Good news for Amur tigers is they have better managed captive breeding program than other tiger sub-species. The captive Amur tigers have more diverse genetic gene pool than wild tigers. If scientists are determined, they could release some of the captive gene pool into wild and ensure genetic diversity.