Expecting mothers hope to give birth to a clinically healthy baby that has one head, a pair of arms and legs, and 10 fingers and 10 toes, among other body parts. Upon giving birth, one mother in China saw that her son, Hong Hong, was born healthy except for one condition — he has 15 fingers and 16 toes.

Doctors diagnosed the 4-month-old boy with the congenital condition — polydactylism — a skeletal defect that gives humans, dogs, and cats extra fingers and toes. This deformation occurs while the fetus is developing in the womb. So, when the fingers and toes are forming, an error occurs, and one single digit is split into two. Polydactylism affects about one out of every 500 to 1,000 babies, according to the Boston Children's Hospital.

The vast majority of occurrences of polydactylyism are sporadic, but some may be due to a genetic defect or underlying hereditary syndrome. African-Americans are more likely to inherit the condition than other ethnic groups.

Hong Hong's mom was also born with six fingers and toes. But while polydactylism can be seen through ultrasounds prenatally, and by eye at birth, the couple claims there were no indications of deformities on prenatal scans. She visited hospitals in Shenzhen, where, after a series of scans, doctors told her that her baby would be perfectly normal, according to NetEase, a China-based internet technology company.

Now, doctors are telling Hong Hong's parents surgery will be extremely difficult. Not only will he have to get the extra fingers and toes removed but he'll also have to undergo thumb reconstruction so that he can grasp objects correctly.

His father, Zou Chenglin told CNN that he's currently to young to undergo surgery.

He will need to undergo surgery at 6 months to a year old, before his bones are set. The surgery could cost as much as 200,000 chinese yuan, the boy's father said, and the couple has sought donations online, raising more than 40,000 yuan (over $6,000).

In 2010, a boy in China who also had 31 toes and fingers underwent successful surgery at age 6. The unnamed boy had problems using his hands because three of his fingers on each hand were conjoined.

Doctors expect Hong Hong to have a successful surgery once he's older.