Pig kidney transplants, new schizophrenia drug: Here are 5 of the biggest medical breakthroughs in 2024

From a pig kidney transplant to restoring genetic deafness, 2024 was a year full of medical breakthroughs.

The breakthroughs include the discovery of a cause of an autoimmune disease, the development of a "game-changing" drug and potential hope for those experiencing end-stage organ failure.

Here are five of the biggest highlights in medical achievements this year:

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Children with hereditary deafness regained their hearing thanks to a type of gene therapy, according to the results of a clinical trial published in the medical journal The Lancet in January.

Investigators from Mass Eye and Ear, a specialty hospital in Boston, examined six children who had a form of genetic deafness called DFNB9, which is caused by a gene mutation that interferes with the transmission of sound signals from the ear to the brain.

PHOTO: A still image taken from video of a study on gene therapy restoring hearing in children with hereditary deafness. (Mass General Brigham)

Gene therapy involved the use of an inactive virus carrying a functioning version of the gene, which was introduced into the inner ears of the six children.

After 26 weeks, five of the six children recovered their hearing and could even conduct "normal conversation."

"Children with this genetic hearing loss…the only treatment option for them until now is [a] cochlear implant," Dr. Zheng-Yi Chen, an associate scientist in the Eaton-Peabody Laboratories at Mass Eye and Ear and study co-investigator, told ABC News. "And of course, [a] cochlear implant can help them tremendously, but it's with its own limitations."

"But with this gene therapy, the children regain hearing, and they were able to speak. So, in a way, the life is totally transformed," he continued. "This study really opened up the whole field that, in the future, we'll be able to develop a treatment for other [types] of genetic hearing loss, for which there is no treatment at all at the moment."

Surgeons at Massachusetts General Hospital (MGH) conducted the world's first genetically-edited pig kidney transplant into a living human in March 2024.

During a four-hour procedure, a surgical team connected the pig kidney's blood vessels and ureter - the duct that carries urine from the kidney to the bladder - with those of 62-year-old Richard Slayman, a man living with end-stage kidney disease.

PHOTO: Surgeons perform the world's first genetically modified pig kidney transplant into a living human at Massachusetts General Hospital, March 16, 2024. (Massachusetts General Hospital)

"For patients with kidney failure, we know that transplantation is the best treatment option, but unfortunately, we face an immense organ shortage," Dr. Leonardo Riella, medical director of kidney transplantation at MGH, told ABC News. "So, we have over 100,000 patients waiting for a kidney transplant in the U.S., and more than 17 patients die every day on the waiting list."