The medical world was abuzz after Dr. John Zhang from the New Hope Fertility Center tried helping an anonymous Jordanian couple who's been trying to start a family for almost 20 years now.

Dr. Zhang altered the mother's egg using a small donor DNA piece in order to prevent the passing on of a fatal genetic mutation, a report said.

The infant was born last April 6, marking the very first time a baby has been born having DNA from three different people - a mother, a father, and an unknown donor.

In an interview with the Daily Mail, Dr. Zhang said, "This is a milestone technique. We now know reconstitution of human eggs can produce a healthy baby. No other technique has been established."

It's been said that the Jordanian couple has failed a couple of times to start a family. The 36-year-old mom, identified as IS, has been suffering from Leigh syndrome, which is a severe neurological disorder.

With four miscarriages, the couple was able to have two children who died from the aforementioned disease at the ages 6 years and eight months, respectively.

The controversial medical procedure has only been approved legally in the United Kingdom and is banned in the U.S. and many parts of the world. Hence, Dr. Zhang worked with a group of doctors in Mexico wherein approval is not a necessity.

They took out the disease-causing DNA from the mother's egg and substituted it with the donor's healthy genetic piece. This medical breakthrough, embryologists believe, is an indication that couples may now avoid passing genetic diseases to their infants in the future.

But a lot of criticisms encircled the successful operation as critics questioned the procedure's safety, implying the children should be monitored for decades to ensure they are healthy. 

Earlier this year, a 12-member team gathered by the National Academies of Sciences, Engineering, and Medicine mentioned it would be moral to test the techniques with safety precautions in place.

Shroukhrat Mitalipov from Oregon Health & Science University said at the time, "We believe it's time to move forward with FDA-approved clinical trials in the United States."

Zhang pointed out that "to save lives is the ethical thing to do". But director of the Center for Law and Biosciences at Stanford University, Henry Greely, called the process "unethical, unwise, and immoral".

He said, "It hasn't been sufficiently proven safe enough to try to use to make a baby."

Additionally, New York Stem Cell Foundation's Dieter Egli warned that the procedure is still not a full success due to the lack of information on what was done.