Kang Jin looks smaller than most of his peers. The toddler, who will soon celebrate his fourth birthday, is the size of a typical 2-year-old child. He always asks his mother to give him a piggyback or be held in her arms, because even walking a few steps tires him out.

Kang Jin suffers from breathing difficulties and poor growth, and his skin has developed a bluish color.

Kang Jin has a congenital heart defect, a condition more common than many realize. Although there is no national survey, experts estimate that for every 1,000 newborns in China, six to eight have a heart abnormality.

Serious defects can be lethal and account for about 20 percent of stillbirths and 30 percent of newborns fatalities.

Deadly as they are, a congenital heart defect is not incurable. More than 90 percent of children born with heart defects can be treated with surgery.

For ethnic children in the less developed areas of western China, where the birth rate is twice that of central and eastern areas, the cost of such a treatment — 15,000 to 50,000 yuan ($2,400 to $8,000) on average — is too high.

This is what Xu Yixuan wanted to address when he launched the charity program, For Our Children, in 2011.

"To date, we've helped 1,615 children from ethnic groups with congenital heart disease to undergo surgery," said Xu, executive president of the Chinese Journalist Volunteers Association for Charity Promotion, an NGO affiliated with the China Charity Federation.

"All the treatments went well. The children have all been discharged from hospitals."

In a recent project, the volunteer association's two medical teams — one from the General Hospital of Armed Police Forces in Beijing and the other from the General Hospital of Guangzhou Military of the People's Liberation Army in Guangdong province — conducted a four-day physical examination of students in Taijiang and Danzhai, two of the least developed counties in Guizhou province.

More than 30,000 students were examined at dozens of kindergartens, primary and middle schools, of which 66 were diagnosed with congenital heart defects requiring surgery.

According to Gao Na, deputy director of the project, the children will be sent to Guangzhou or Beijing for treatment after Spring Festival.

The volunteer association will not only pay for each child's treatment, but also their airline tickets.