De novo SOX10 Nonsense Mutation in a Patient with Kallmann Syndrome, Deafness, Iris Hypopigmentation, and Hyperthyroidism

: Kallmann syndrome (KS) is a clinically and genetically heterogeneous disorder characterized by hypogonadotropic hypogonadism and olfactory dysfunction. Recently, mutations in SOX10, a well-known causative gene of Waardenburg syndrome (WS), have been identified in a few KS patients with additional developmental defects including hearing loss. However, the understanding of SOX10 mutation associates with KS and other clinical consequences remains fragmentary. A 30-year-old Chinese male patient presented with no pubertal sex development when he was at the age of twelve years. Additionally, he showed anosmia, sensory deafness, and blue irises. Last year, he developed clinical symptoms of hyperthyroidism with a fast heartbeat, heat intolerance and weight loss. Blood examinations revealed low levels of FSH, LH, and testosterone. Thyroid function showed high levels of FT3, FT4 and extremely low level of TSH. Molecular analysis detected a de novo (c.565G>T/p.E189X) mutation in SOX10, which has previously been reported in a patient with WS4 (WS with Hirschsprung). The mutation was predicted to be probably damaging. These results highlight the significance of SOX10 haploinsufficiency as a genetic cause of KS. Importantly, our result implies that the same SOX10 mutation can underlie both typical KS and WS, while the correlation between SOX10 and hyperthyroidism still needs to be clarified in the future.