NBC News Chief Foreign Correspondent Richard Engel announced Thursday that his son Henry, 6, has died.
"Our beloved son Henry passed away. He had the softest blue eyes, an easy smile and a contagious giggle. We always surrounded him with love and he returned it, and so much more. Mary and Richard," Engel wrote on Twitter.
The TODAY regular shared a link to a memorial page on the Texas Children's Hospital website, which offered more details on Henry's life and his battle with Rett syndrome, a genetic brain disorder without a treatment or cure.
According to the National Institute of Neurological Disorders and Stroke, Rett syndrome can cause loss of use of the hands, problems with walking, seizures, slowed brain and head growth and intellectual disability.
Born on Sept. 29, 2015, Henry was slow to reach certain developmental milestones as an infant. After a series of medical exams and a genetic test, doctors discovered that he had a mutation in his MECP2 gene.
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"MECP2 mutations cause Rett syndrome, a disorder that typically affects girls after their first birthday, robbing them of learned skills and leaving them with cognitive deficits, loss of speech, and a variety of motor difficulties," the Texas Children's Hospital page explains.
The Engel family brought Henry to the hospital's Duncan Neurological Research Institute (Duncan NRI) in 2018 to seek additional answers. The Duncan NRI's Founding Director Dr. Huda Zoghbi studied Henry's mutation closely.
“Henry was special in so many ways. His loving and endearing smile, and the way he connected with his eyes, stole my heart from the time I met him. His quiet fight against this terrible disease was incredible," the doctor wrote in a tribute to her little patient.
According to Zoghbi, Henry left a lasting impression on the entire Duncan NRI team and their ongoing Rett research.
"We will continue to push as hard as possible to develop treatments. This is how we will honor his life,” the doctor continued.
Over the years, Engel has shared regular updates on his son's condition with the TODAY team and has been candid about the struggles and the joys of parenting a child with special needs.
In March 2022, he shared a somber update on Henry's health and said his son had “taken a turn for the worse.”
“His condition progressed and he’s developed dystonia: uncontrolled shaking/ stiffness. He was in the hospital for 6 weeks, but is now home and getting love from brother Theo," he wrote on Twitter at the time.
On his tribute page, Henry is described as someone who "made the best of every single day and worked tirelessly in his many physical and developmental therapies."
"He continues to be an inspiration for Dr. Zoghbi and her team as they work to find effective treatments for Rett syndrome, and they already are making significant progress with Henry’s own cells," the post says.
This story first appeared on TODAY.com. More from TODAY: