What is Opitz G/BBB Syndrome, MID1-related? Opitz G/BBB syndrome, MID1-related (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 inherited in an X-linked manner. This means the condition is typically more severe in individuals assigned male at birth (XY). Individuals assigned female at birth (XX) usually do not have symptoms of the condition. 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 Most XX individuals (who are typically assigned female at birth) are carriers of MID1-OS and do not have symptoms. However, some carriers may exhibit mild symptoms such as an increased distance between the eyes (hypertelorism). 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 individuals assigned male at birth (XY). How is Opitz G/BBB Syndrome, MID1-related treated? There is no cure for Opitz G/BBB syndrome, which is MID1-related. Treatment is directed at managing an individual's specific symptoms. Most 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