Loss-of-function SOX10 mutation in a patient with kallmann syndrome, hearing loss, and iris hypopigmentation

Background: Kallmann syndrome (KS) is a clinically and genetically heterogeneous disorder consisting of hypogonadotropic hypogonadism and anosmia. KS is occasionally associated with deafness. Recently, mutations in SOX10, a well-known causative gene of Waardenburg syndrome (WS) characterized by deafness, skin/hair/iris hypopigmentation, Hirschsprung disease, and neurological defects, have been identified in a few patients with KS and deafness. However, the current understanding of the clinical consequences of SOX10 mutations remains fragmentary. Case Report: A Japanese male patient presented with sensory deafness, blue irises, and anosmia, but no hair/skin hypopigmentation, Hirschsprung disease, or neurological abnormalities. He showed no pubertal sex development at 15.1 years of age. Blood examinations revealed low levels of FSH and testosterone. Results: Molecular analysis detected a de novo p.Leu145Pro mutation in SOX10, which has previously been reported in a patient with WS and Hirschsprung disease. The mutation was predicted to be probably damaging. The mutant protein barely exerted in vitro transactivating activity. Conclusions: These results highlight the significance of SOX10 haploinsufficiency as a genetic cause of KS with deafness. Importantly, our data imply that the same SOX10 mutations can underlie both typical WS and KS with deafness without skin/hair hypopigmentation, Hirschsprung disease, or neurological defects.