SG03 A case of Bazex–Dupré–Christol syndrome (BDCS)

Abstract A 36-year-old man presented to the dermatology department in 2013 with a pink papule on his neck. He had no significant past medical history and took no regular medications. He was born with sparse hair and had milia on his face, neck and ears since childhood. His nonidentical twin daughters were born with milia confined to the head and neck. His mother and maternal aunt had histories of multiple basal cell carcinomas (BCCs), hypotrichosis and follicular atrophoderma and were subsequently diagnosed with Bazex–Dupré–Christol syndrome (BDCS). On examination, he had a superficial BCC on his right posterior neck, with prominent follicular atrophoderma affecting the dorsum of his hands, elbows and feet. He had milia on his ears bilaterally. The BCC was successfully treated with imiquimod 5% cream. The initial genetic testing was uninformative. He was subsequently lost to follow-up but presented again in 2021 with a BCC on his lower eyelid. In 2022 a pertinent paper was published in the British Journal of Dermatology by Liu et al. (Liu Y, Banka S, Huang Y et al. Germline intergenic duplications at Xq26.1 underlie Bazex–Dupré–Christol basal cell carcinoma susceptibility syndrome. Br J Dermatol 2022; 187: 948–61). This revealed new insights into the genetic aetiology for the syndrome, and hence the patient was contacted to consider further genetic testing. Whole-genome sequencing was performed, which identified the same duplications in noncoding sections of chromosome Xq26.1 as highlighted by Liu et al. BDCS is a rare X-linked dominant condition characterized by a triad of BCC, follicular atrophoderma and hypotrichosis. It may also be accompanied by milia, hypohidrosis and trichoepithelioma (AlSabbagh M, Baqi M. Bazex–Dupré–Christol syndrome: review of clinical and molecular aspects. Int J Dermatol 2018; 57: 1102–6). It has been previously thought that there is no single gene solely responsible for BDCS; however, in 2022, Liu et al. suggested that dysregulation of the gene ARHGAP36, resulting from duplications in noncoding sections of chromosome Xq26.1, might be implicated. ARHGAP36 is a flanking centromeric gene near the control hair follicular stem cell compartment (Liu et al.). Our case highlights the importance of considering BDCS as a differential diagnosis in patients presenting with early-onset BCC. Having a confirmed diagnosis enables tailored clinical management with early preventative measures and the opportunity for genetic counselling for future generations of affected individuals.