Recurrent splice-site mutation in MBTPS2 underlying IFAP syndrome with Olmsted syndrome-like features in a Chinese patient.

Mutations in MBTPS2 have been reported to cause a broad phenotypic spectrum of X-linked genodermatoses, including IFAP (ichthyosis follicularis; atrichia and photophobia) syndrome (OMIM 308205) with or without BRESHECK (brain anomalies, retardation of mentality and growth, ectodermal dysplasia, skeletal malformations, Hirschsprung disease, ear deformity and deafness, eye hypoplasia, cleft palate, cryptorchidism, and kidney dysplasia/hypoplasia) syndrome, keratosis follicularis spinulosa decalvans (KFSD; OMIM 308800) and an X-linked form of Olmsted syndrome. We report a recurrent intronic mutation in MBTPS2 (c.671-9T>G) in a Chinese patient with the typical triad of IFAP syndrome (i.e. ichthyosis, atrichia and photophobia), along with pachyonychia, palmoplantar and periorificial keratoderma, which were reminiscent of Olmsted syndrome. Interestingly, this mutation was previously reported in two cases of IFAP without keratoderma, which suggests clinical heterogeneicity of the same mutation in MBTPS2. The concomitance of Olmsted syndrome-like features in this patient with IFAP may challenge the existence of the X-linked form of Olmsted syndrome as an independent condition.