Hereditary Benign Intraepithelial Dyskeratosis: Report of a Case and Re-examination of the Evidence for Locus Heterogeneity.

BACKGROUND: Hereditary benign intraepithelial dyskeratosis (HBID) is a rare autosomal-dominant disorder of the conjunctiva and oral mucosa first described in and predominantly affecting descendents of Haliwa-Saponi Native Americans. We report a spontaneous case of histopathologically-confirmed HBID affecting an individual not of Native American ancestry. MATERIALS AND METHODS: Report of a case with histopathologic examination of an excised conjunctival specimen as well as molecular and cytogenetic analysis. RESULTS: A Caucasian boy with a history of oral lesions and conjunctival injection from birth developed bilateral corneal opacities at age 5 and underwent penetrating keratoplasty, with recurrence of the corneal opacification shortly after surgery. Examination of a conjunctival biopsy specimen revealed features consistent with HBID. Copy number variant (CNV) analysis revealed a de novo 4q35 duplication that overlapped the duplication previously associated with HBID, although no genes were identified in the common interval. NLRP1 gene sequencing failed to reveal a presumed pathogenic variant. CONCLUSIONS: HBID may develop de novo in individuals who are not of Native American ancestry. The absence of coding regions in a duplicated region of 4q35 common to both the individual that we report and previously associated with HBID raises questions regarding the significance of this CNV in the pathogenesis of HBID.