What is Rett syndrome? Richard Engel mourns death of 6-year-old son Henry

Richard Engel, chief foreign correspondent for NBC News, announced on Thursday that his six-year-old son Henry had passed away from a rare neurological disorder.

“Our beloved son Henry passed away,” Engel wrote in a tweet signed both by himself and his wife, Mary Forrest. “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.”

Engel signed the tweet with a link to a Texas Children’s Hospital page, titled “Remembering and Honoring Henry,” which included a link for donations to support research in Henry’s name.

Henry – who was born September 2015 – was just an infant when Engel and his wife noticed that their son was struggling to hit typical developmental milestones, according to the tribute page. After a series of tests, they found that Henry had a mutation in his MECP2 gene, the mutation that is responsible for Rett syndrome.

Rett syndrome is an incurable genetic neurological disorder that typically affects girls, but can also, in rare cases, affect boys. Rett syndrome leads to many developmental delays, including “loss of speech and a variety of motor difficulties”.

The International Rett Syndrome Foundation reported that the ​​genetic neurological disorder occurs in one of every 10,000 female births, and can be recognised in children between six to 18 months old.

Most babies with Rett syndrome seem to develop as expected within the first six months of life, and are not typically diagnosed at this age. Parents and doctors may not notice a slowing of development until their child is older, but over time, children with Rett syndrome may experience increasing problems with motor skills, coordination, and communication. The Mayo Clinic also states that other symptoms of Rett syndrome include unusual hand movements, seizures and breathing issues.

Rett syndrome can often be misdiagnosed as autism, cerebral palsy, or a non-specific developmental delay. Blood testing can confirm the presence of the MECP2 mutation which causes Rett syndrome. However, the MECP2 mutation is also seen in other disorders, so a Rett syndrome diagnosis requires additional clinical testing based on observed signs and symptoms.

There are six stages of Rett syndrome, according to the International Rett Syndrome Foundation. The first is the early onset stage, which occurs at six months to 1.5 years when symptoms of the disorder are easily overlooked. The rapid destructive stage happens when a child is one to four years old, and begins to lose the ability to perform skills they previously had. The third stage, the plateau stage, ranges from preschool age to adulthood where problems with movement continue but behaviour may slightly improve. The final stage, the late motor deterioration stage, can last for years or decades. It’s marked by reduced mobility, muscle weakness, joint contractures, and scoliosis. However, not all children with Rett syndrome move through the stages similarly.

Due to the rarity of Rett syndrome, not much research has been published on its life expectancy. Although, data from the Natural History Study have determined that a girl with a greater than 75 per cent chance of reaching age 30 and a greater than 65 per cent chance of reaching age 40. On average, most individuals with the condition survive into their 40s or 50s.

Since 2018, Henry’s mutation has been studied by Dr Huda Zoghbi at the Texas Children’s Hospital’s Duncan Neurological Research Institute. In another tweet shared on Thursday, Richard Engel wrote that “researchers are making amazing progress using Henry’s cells to help cure RETT Syndrome so others don’t have to endure this terrible disease.”

Treatment for Rett syndrome is continually being researched by Dr Zoghbi and her team as “they already are making significant progress with Henry’s own cells.”