Bryant-Li Bhoj Neurodevelopmental Syndrome 2; BRYLIB2
OMIM number: 619721
Comments closing date: 09/03/2026
Bryant-Li-Bhoj neurodevelopmental syndrome is a rare genetic condition caused by a change in a
gene called H3-3A, which plays an important role in how DNA is packaged and used inside cells.
When this gene does not work properly, it can affect how the brain and body develop. The condition can also result from changes in gene H3F3B, which encode a nearly identical protein. Because these proteins have the same biological role, the resulting phenotype can be the same, whether the pathogenic variant is in H3-3A or H3-3B. Children with this condition typically show global developmental delay, meaning they learn skills such as sitting, walking, and talking later
than expected. Many have severe intellectual disability, limited or absent speech, and low muscle tone. Some children develop seizures, feeding difficulties, reflux, and poor growth. Other rarer features have been reported to include congenital heart defects, brain malformations and genital/urinary abnormalities in biological males. This condition is autosomal dominant, meaning a child can be affected if they inherit one altered copy of the gene. In many cases, the genetic change happens for the first time in the child and is not inherited from either parent. That being said, germline mosaicism (a gene alteration in some egg/sperm cells) could present a way in which this condition could be hereditary. There is no cure, but supportive treatments such as physiotherapy, occupational therapy, speech therapy, and special educational support can help improve an individual’s quality of life. Medical care can also help manage symptoms like seizures or feeding difficulties. Knowledge about life expectancy with this condition is unclear as data is limited.
