What is Opitz G/BBB Syndrome, MID1-related? Opitz G/BBB syndrome, MID1-related or MID1-OS, is an inherited disease that causes multiple birth defects and intellectual disability. The condition is caused by harmful genetic changes (variants) in the MID1 gene. MID1-OS is an X-linked disease, meaning that people assigned male at birth (XY) typically have more severe symptoms, while those assigned female (XX) at birth typically have mild or no symptoms. The symptoms of MID1-OS include unique facial features and birth defects involving the throat, genitals, heart, and brain. They may also have cleft lip or cleft palate. Over 30% of individuals have developmental delays or intellectual disabilities. The severity of symptoms can vary widely, even among family members. Almost all individuals with MID1-OS have facial abnormalities. Most commonly, the distance between the eyes is increased (hypertelorism). Other characteristic facial features include a wider bridge of the nose, a prominent forehead, and low-set ears. Additional considerations for carriers Individuals assigned female at birth (XX) are considered carriers and usually do not have disease symptoms, but they may have increased distance between the eyes (hypertelorism) with no other symptoms. How common is Opitz G/BBB Syndrome, MID1-related? Opitz G/BBB syndrome, MID1-related, is thought to affect 1 in 50,000 to 1 in 100,000 males. How is Opitz G/BBB Syndrome, MID1-related treated? There is no cure for Opitz G/BBB syndrome, MID1-related. Treatment is directed at managing the specific symptoms an individual has. Most of the birth defects can be treated with corrective surgery. Individuals with developmental delay will benefit from early intervention and other supportive services beginning at a young age. A team of specialists, including a speech/language pathologist, surgeon, cardiologist, pulmonologist, and ophthalmologist, can help treat symptoms as needed. What is the prognosis for a person with Opitz G/BBB Syndrome, MID1-related? The prognosis of an individual with Opitz G/BBB syndrome, MID1-related, varies depending on the severity of the symptoms. Surgery can treat many of the symptoms of the condition. Most individuals can live a relatively normal lifespan. Some will need support throughout their entire lives. Other names forOpitz G/BBB syndrome, MID1-related OS Opitz G/BBB Syndrome, Type 1 Opitz Syndrome X-Linked Opitz G/BBB X-Linked Opitz Syndrome XLOS References Fontanella et al., 2008, Hum Mutat., 29(5):584-94, PMID: 18360914 Meroni, 2023, https://www.ncbi.nlm.nih.gov/books/NBK1327/ Micale et al., 2023, Pediatr Res., 93(5):1208-1215, PMID: 35953512 Perea-Cabrera et al., 2023, Mol Genet Genomic Med., 11(9):e2234, PMID: 37498300