Main Theme: Otology
Introduction: Waardenburg syndrome (WS) is a genetic condition that is commonly inherited in an autosomal dominant manner. Hallmark presentations of WS include congenital hearing loss, heterochromia, hypertelorism and a white forelock. There are four types of Waardenburg syndrome, usually distinguished by their presentation and genetic cause. Sensorineural hearing loss (SNHL) is a prevalent feature of individuals with WS.
Methods: This case reports 2 sisters with Type 1 WS (WS1). Medical records were obtained through online databases. Family tree diagrams were constructed to demonstrate the inheritance pattern.
Results: The older sister, Child A presents with a white forelock, dystopia canthorum, heterochromia irides and a flat nasal bridge. She had a bilateral Universal Newborn Hearing Screen (UNHS) referral result, following which diagnostic testing revealed bilateral SNHL. This differed from prior family history of WS presenting with unilateral hearing loss. The type of WS was concluded to be familial heterozygous PAX3 c.274G>T p/(glu92*) pathogenic variant. The younger sister also had bilateral referral UNHS results and bilateral SNHL on diagnostic testing. The same pathogenic variant was detected– consistent with her mother and older sister.
Conclusion: Child A and B’s mother, grandmother and great-grandfather displayed unilateral H. Child A and B, however, both presented with bilateral HL. Hearing loss has appeared in 4 generations of the family. Penetrance of SNHL in WS1 was found to be 69% in a study by Newton and interfamilial variation in penetrance has been showed to be very wide in families with WS1.