Opitz G/BBB syndrome

Opitz G/BBB syndrome is a genetic condition that causes several abnormalities along the midline of the body. "G/BBB" represents the first letters of the last names of the families first diagnosed with this disorder and "Opitz" is the last name of the doctor who first described the signs and symptoms. There are two forms of Opitz G/BBB syndrome, X-linked Opitz G/BBB syndrome and autosomal dominant Opitz G/BBB syndrome. The two forms are distinguished by their genetic causes and patterns of inheritance. The signs and symptoms of the two forms are generally the same.

Nearly everyone with Opitz G/BBB syndrome has wide-spaced eyes (ocular hypertelorism). Affected individuals commonly have defects of the voice box (larynx), windpipe (trachea), or esophagus. These throat abnormalities can cause difficulty swallowing or breathing, in some cases resulting in recurrent pneumonia or life-threatening breathing problems. A common defect is a gap between the trachea and esophagus (laryngeal cleft) that allows food or fluids to enter the airway. The cleft can vary in size, and infants may struggle to breathe when feeding. Most males with Opitz G/BBB syndrome have genital abnormalities such as the urethra opening on the underside of the penis (hypospadias), undescended testes (cryptorchidism), an underdeveloped scrotum, or a scrotum divided into two lobes (bifid scrotum). These genital abnormalities can lead to problems in the urinary tract.

Mild intellectual disability and developmental delay occur in about 50 percent of people with Opitz G/BBB syndrome. Affected individuals have delayed motor skills, such as walking, speech delay, and learning difficulties. Some people with Opitz G/BBB syndrome have features of autistic spectrum disorders, which are characterized by impaired communication and socialization skills. About half of affected individuals also have an opening in the lip (cleft lip) with or without an opening in the roof of the mouth (cleft palate). Some have cleft palate without cleft lip. Less common features of Opitz G/BBB syndrome, affecting less than half of people with this disorder, include minor heart defects, an obstruction of the anal opening (imperforate anus), and brain defects such as a small or absent connection between the left and right halves of the brain (corpus callosum). Distinct facial features that may be seen in this disorder include a prominent forehead, widow's peak hairline, flat nasal bridge, thin upper lip, and low-set ears. These features vary among affected individuals, even within the same family.