SNP Shot: Genomic Insights

Branchiootorenal (BOR) syndrome is a condition affecting development, primarily impacting neck tissues and causing malformations of the ears and kidneys. The signs and symptoms of BOR syndrome exhibit considerable variability, even within the same family. Branchiootic (BO) syndrome shares many features with BOR syndrome, but individuals with BO syndrome do not have kidney problems. Given their similarities, researchers often group these conditions together as BOR/BO syndrome or branchiootorenal spectrum disorders.

The term "Branchio-" relates to the second branchial arch, a structure present in the developing embryo which forms tissues in the front and sides of the neck. In individuals with BOR/BO syndrome, abnormal development of this arch can lead to the formation of branchial cleft cysts, which are masses in the neck. Some affected individuals may also have fistulae, which are abnormal holes or pits on the side of the neck, typically just above the collarbone. These fistulae can create tunnels extending into the neck and potentially exiting in the mouth near the tonsil. Branchial cleft cysts and fistulae are prone to infection and are often surgically removed to prevent complications.

The terms "Oto-" and "-otic" refer to the ear. The majority of individuals with BOR/BO syndrome experience hearing loss and other ear abnormalities. The hearing loss may be sensorineural (resulting from inner ear abnormalities), conductive (resulting from changes in the middle ear bones), or mixed (a combination of inner and middle ear abnormalities). Some affected individuals have small skin holes (preauricular pits) or extra tissue (preauricular tags) located just in front of the ear.

The term "Renal" pertains to the kidneys. BOR syndrome, unlike BO syndrome, causes structural and functional abnormalities of the kidneys. These abnormalities can range in severity and may affect one or both kidneys. In some instances, end-stage renal disease (ESRD) may develop later in life. ESRD is a serious condition where the kidneys are no longer able to effectively filter fluids and waste products from the body.

Inheritance:

BOR/BO syndrome follows an autosomal dominant inheritance pattern. This means that having only one copy of the mutated gene in each cell is enough to cause the disorder. In approximately 90% of cases, the affected individual inherits the mutation from a parent who also has the condition. The remaining cases are due to new gene mutations and occur in individuals with no family history of BOR/BO syndrome.