Individuals with the BO syndrome are affected by the same branchial and otic anomalies as those seen in individuals with the branchiootorenal syndrome (see BOR1, 113650), but lack renal anomalies (Vincent et al., 1997).
Although Melnick ... Individuals with the BO syndrome are affected by the same branchial and otic anomalies as those seen in individuals with the branchiootorenal syndrome (see BOR1, 113650), but lack renal anomalies (Vincent et al., 1997). Although Melnick et al. (1978) maintained that the BO syndrome is distinct from the BOR syndrome because of the lack of renal anomalies and variable presence of deafness in the former, Cremers and Fikkers-van Noord (1980) suggested that the 2 syndromes represent a single entity. See 113600 for a discussion of branchial cleft anomalies, which may be related. - Genetic Heterogeneity of Branchiootic Syndrome See also BOS2 (120502), which maps to chromosome 1, and BOS3 (608389), which maps to 14q23 and is caused by mutations in the SIX1 gene (601205).
Fourman and Fourman (1955) described a large multigenerational family in which 17 members had preauricular pits, 12 of whom also had mild to severe sensorineural hearing loss. Among family members without preauricular pits, 3 had hearing loss: one ... Fourman and Fourman (1955) described a large multigenerational family in which 17 members had preauricular pits, 12 of whom also had mild to severe sensorineural hearing loss. Among family members without preauricular pits, 3 had hearing loss: one of these individuals had a branchial pit. Some reported onset of hearing loss in childhood, whereas others had onset beginning at about age 20 years. Audiograms showed both high and low tone loss, usually high tone more than low. There was no evidence of vestibular disorder. The authors suggested that ear pits, deafness, and branchial fistulae were independent effects of a single dominant gene with incomplete penetrance. Wildervanck (1962) reported a family in which 14 members had either deformed auricles, marginal pits, or preauricular appendages. Two had a moderate conductive deafness: bilateral in 1 and unilateral in the other. The mode of inheritance was dominant with full penetration. Wildervanck (1962) suggested this was a different syndrome from that described by Fourman and Fourman (1955). McLaurin et al. (1966) reported a kindred with branchial anomalies and associated hearing impairment similar to the kindred described by Wildervanck (1962). Brusis (1974) reported a kindred similar to the one described by Fourman and Fourman (1955). Vincent et al. (1997) reported 2 families with the BO syndrome. Clinical features included branchial cervical fistulae, cup-shaped pinnae, preauricular pits, and sensorineural, conductive, or mixed hearing loss. There was no evidence of renal anomalies. Spruijt et al. (2006) reported an infant with severe obstructive sleep apnea caused by laryngomalacia, pharyngomalacia, glossoptosis, and tracheobronchomalacia. He also had bilateral branchial fistulae and ear anomalies, including ear pits, simple helices, and slight cup-shaped and low-set left ear. The features suggested BO syndrome. Other findings included micro- and retrognathia, but kidneys and hearing were normal. Surgical intervention improved the upper airway obstruction, but mild delay and mental and motor development were observed at age 11 months. His mildly affected mother showed mild retrognathia, left-sided branchial neck fistula, left-sided preauricular pit, and right-sided branchial cyst in the neck. Kidney ultrasound and hearing were normal. Both mother and son were heterozygous for a truncating mutation in the EYA1 gene (601653.0015). Spruijt et al. (2006) emphasized the phenotypic variability of BO syndrome associated with EYA1 mutations.
Vincent et al. (1997) demonstrated a 2-bp insertion in the EYA1 gene (601653.0003) in 1 of 2 families with BO syndrome. In the other family, they detected an 8-bp deletion (601653.0004).
Spruijt et al. (2006) identified ... Vincent et al. (1997) demonstrated a 2-bp insertion in the EYA1 gene (601653.0003) in 1 of 2 families with BO syndrome. In the other family, they detected an 8-bp deletion (601653.0004). Spruijt et al. (2006) identified a heterozygous mutation in the EYA1 gene (601653.0014) in an infant with a variant form of BO syndrome. - Anterior Segment Anomalies with or without Cataract Azuma et al. (2000) examined genomic DNA isolated from patients with various types of developmental eye anomalies for EYA1 mutations by use of PCR-SSCP and sequencing. They identified 3 novel missense mutations in patients who had congenital cataracts and ocular anterior segment anomalies (see, e.g., 601653.0008-601653.0009).