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Ichthyosis follicularis with atrichia and photophobia (IFAP) syndrome is a rare genodermatosis characterized by a classic triad of follicular ichthyosis, alopecia, and photophobia. We report a Chinese patient displaying features of IFAP triad along with painful palmoplantar keratoderma, recurrent infections, periorificial keratotic plaques, nail dystrophy, and pachyonychia. Whole‐exome sequencing revealed an intronic variant (NM_015884.3: exon7:c.970+5G>A) in the gene MBTPS2. Sanger sequencing confirmed that the variant segerated with phenotype in the family. Sequencing of cDNAs derived from the patient indicated the variant introduced a new splice donor site, leading to partial skipping of exon 7 (r.951_970del). An in vitro mini‐gene assay also revealed abnormal splicing of exon 7. This study presents a case complicated with X‐linked IFAP syndrome and Olmsted syndrome, and highlights the significance of using validation assays to identify the pathogenicity of intronic variants in MBTPS2. [ABSTRACT FROM AUTHOR]

Olmsted syndrome (OS) is a rare genetic disorder, characterized by painful palmoplantar keratoderma (PPK), periorificial and intertriginous hyperkeratoses, and alopecia. Fewer than 75 cases have been described. Variants in TRPV3 result in constitutive activation of transient receptor potential vanilloid 3, leading to increased epidermal growth factor receptor (EGFR) signaling, palmoplantar epidermal hyperproliferation, and exquisite lesional pain. We describe pre‐school aged twins with OS with partial improvement from oral erlotinib, an EGFR inhibitor, but dramatic reduction of their persistent palmoplantar thickening and pain from adding acitretin. [ABSTRACT FROM AUTHOR]

Olmsted syndrome is a very rare congenital disorder, characterized by palmoplantar keratoderma and periorificial keratotic lesions. Recently, TRPV3 was reported to be a causative gene of Olmsted syndrome. We identified a heterozygous missense mutation of TRPV3, c.1703G>T, p.Gly568Val, in a Japanese patient with Olmsted syndrome. To the best of our knowledge, this is the first report of a Japanese patient with Olmsted syndrome harboring a missense mutation in TRPV3. We conducted in silico analysis of TRPV3 to evaluate whether the p.Gly568Val leads to structural changes in the TRPV3 selectivity filter. The selectivity filter was shown to become dilated and hyperpermeable as a result of genetic mutation (p.Gly573Ser, p.Tr692Gly or p.Gly568Val) as well as after a change in temperature (300 K to 310 K). In silico analysis of TRPV3 could be a useful approach in predicting mutation-induced activated states of ion channels, and thus enrich our understanding of the pathogenesis of Olmsted syndrome. [ABSTRACT FROM AUTHOR]

A quiz concerning painful callosities in a young boy is presented.