Brooke Greenberg

The Greenbergs made many visits to nearby Johns Hopkins Children's Center and even took Brooke to New York’s Mount Sinai Hospital, searching for information about their daughter’s condition. When geneticists sequenced Greenberg's DNA, they found that the genes associated with the premature aging diseases were normal, unlike the mutated versions in patients with Werner syndrome and progeria.

In April 2017, NTD Television reported about Manpreet Singh from a village in the northern Mansa, India. At 22 years old, he is only 23 inches (58 cm) tall and was born after ten months. He did not show any signs of growth and development such as speaking after six months. Doctors said his condition could be caused by his late birth and a deficiency of growth hormones.

Another reported case in 2017 is Angus Palmes from Macclesfield, UK. At the age of 13 he weighs 2.14 stone (30.0 lb) and has a height of 3 feet 1 inch (94 cm). He is believed to have a chromosomal translocation of 15/20 and a partial trisomy of 22q12.3.

In May 2015, it was reported that Layla Qualls of Oklahoma looks as if she is 9 or 10 months old, but is 3 years old. She is among seven children worldwide with Syndrome X that are being studied by researchers at the University of California, Los Angeles. In their ongoing research they found that the blood of Syndrome X children appears to age normally. Layla has also been featured in a TLC documentary titled "The Girls Who Don't Age". This documentary aired July 18, 2016 on TLC.

In July 2016, it was reported that Alyssa Pennington of New Mexico looks like she is five years old, but is 12 years old. She is another Syndrome X case.

Another case that has been reported in July 2016 is Jenifer Sandoval of Colorado. Although she looks like she is four years old, she is 22 years old.

Brooke Greenberg died on October 24, 2013, at the Herman and Walter Samuelson Children's Hospital at Sinai Medical Center in Baltimore, the same hospital where she was born. Her funeral service took place on October 27, 2013, and that same morning, she was buried at Baltimore Hebrew Cemetery - Berrymans Lane, in Reisterstown, Maryland. The cause of her death was bronchomalacia, a medical condition usually occurring in children, which results in difficulty breathing due to weak cartilage in the walls of the bronchial tubes.

During an interview on the talk show Katie, her father stated that between the ages of four and five, she stopped growing. Child Frozen In Time, a documentary about Brooke, was first broadcast on TLC on August 9, 2009.

In 2009, Walker said, "There've been very minimal changes in Brooke's brain … Various parts of her body, rather than all being at the same stage, seem to be disconnected." Walker noted that Brooke's brain, for example, was not much more mature than that of a newborn infant. He estimated her mental age at around nine months to a year old. Brooke could make gestures and recognize sounds but could not speak. Her bones were like those of a ten-year-old, and she still had her baby teeth, which had an estimated developmental age of about eight years. Said Walker, "We think that Brooke's condition presents us with a unique opportunity to understand the process of aging." "Different parts of her body are developing at different rates, as if they were not a unit but parts of separate organisms," Walker explained. Dr. Walker did not say whether the genes responsible for development are the same ones responsible for aging.

In 2006, Richard Walker, an endocrine physiologist at the University of South Florida College of Medicine, said that Brooke's body was not developing as a coordinated unit but as independent parts that were out of synchronization. She was never diagnosed with any known genetic disorder or chromosomal abnormality that would help explain why. Her telomeres seemed to be shortening at the normal rate.

Over several years, the Greenbergs visited many specialists, looking for an explanation for their daughter's strange condition, yet there was no diagnosis of any known genetic syndrome or chromosomal abnormality. In 2001, when Dateline documented Brooke at eight years of age, she was still the size of a six-month-old infant, weighing just 13 lb (5.9 kg) at 30 inches (76 cm) tall. The family still had no explanation. Brooke's mother Melanie said, "They [the specialists] just said she’ll catch up. Then we went to the nutritionist, the endocrinologist. We tried the growth hormone…". The growth hormone treatment had no effect. Howard, Brooke's father, said, "I mean, she did not put on an ounce, or she did not grow an inch... That’s when I knew there was a problem." After the growth hormone administration failed, the doctors, unable to diagnose a known condition, named her condition Syndrome X.

Brooke Megan Greenberg (January 8, 1993 – October 24, 2013) was an American who remained physically and cognitively similar to a toddler, despite her increasing age. She was about 30 in (76 cm) tall, weighed about 16 lb (7.3 kg) and had an estimated mental age of nine months to one year. Brooke's doctors termed her condition Syndrome X.

Brooke was born on January 8, 1993 to parents Howard and Melanie Greenberg at Sinai Hospital in Baltimore, Maryland. She was delivered by Caesarean section, one month before her due date due to "intermittent growth", weighing just four pounds (1.8 kg). She was born with anterior hip dislocation, a condition that caused her legs to be swiveled upward toward her shoulders; it was corrected surgically. Otherwise, Brooke appeared to be a normal infant. She was the third of four girls born to her parents.

María Audenete do Nascimento, a Brazilian woman who lives in the town of Caucaia near Fortaleza in the state of Ceará, Brazil, was once thought to have also been suffering from a condition similar to Greenberg's. She was reportedly born in May 1981 but stopped growing after nine months. She has been diagnosed with severe hypothyroidism.

Dr. Walker believed that Brooke Greenberg's condition had resulted from a failure of central control genes. He identified two more people with similar developmental issues: Gabrielle Williams of Montana (born in 2004) and Nicky Freeman of Australia (born on December 28, 1969), a middle aged man who looks like a preteen boy.