SNP Shot: Genomic Insights

Auriculo-condylar syndrome is a disorder impacting facial development, notably the ears and lower jaw (mandible).

Individuals with auriculo-condylar syndrome commonly exhibit outer ear malformations ("auriculo-" relates to the ears). A key characteristic is the "question-mark ear," a distinctive ear shape where a split separates the upper ear from the earlobe. Other possible ear abnormalities include cupped ears, simplified ears (fewer folds and grooves), narrow ear canals, skin tags near the ears, and ears that angle backward. Hearing loss may also occur.

Mandible abnormalities are another defining feature of auriculo-condylar syndrome. These frequently include a small chin (micrognathia) and temporomandibular joint (TMJ) dysfunction. The TMJ connects the lower jaw to the skull, and TMJ issues affect jaw alignment, potentially hindering mouth opening and closing. "Condylar" in the syndrome's name refers to the mandibular condyle, the upper part of the mandible forming part of the TMJ.

Additional characteristics may include prominent cheeks, a small mouth (microstomia), facial asymmetry (differences between the face's two sides), and cleft palate. These features vary in severity and presence, even within families.

Inheritance:

The condition follows an autosomal dominant inheritance pattern, meaning typically only one copy of the mutated gene is needed to cause the syndrome. Some affected individuals inherit the mutation from a parent with the condition. In other instances, the mutation is new and occurs in individuals with no family history of the disorder. Some individuals carrying one altered copy of the GNAI3 or PLCB4 gene show no signs of auriculo-condylar syndrome (known as reduced penetrance). The reasons behind this variable expression are not fully understood.