Frontal fibrosing alopecia (FFA) is a recently described inflammatory and scarring type of hair loss affecting almost exclusively women. Despite a dramatic recent increase in incidence the aetiopathogenesis of FFA remains unknown. We undertake genome-wide association studies in females from a UK cohort, comprising 844 cases and 3,760 controls, a Spanish cohort of 172 cases and 385 controls, and perform statistical meta-analysis. We observe genome-wide significant association with FFA at four genomic loci: 2p22.2, 6p21.1, 8q24.22 and 15q2.1. Within the 6p21.1 locus, fine-mapping indicates that the association is driven by the
HLA-B*07:
02 allele. At 2p22.1, we implicate a putative causal missense variant in
CYP1B1
, encoding the homonymous xenobiotic- and hormone-processing enzyme. Transcriptomic analysis of affected scalp tissue highlights overrepresentation of transcripts encoding components of innate and adaptive immune response pathways. These findings provide insight into disease pathogenesis and characterise FFA as a genetically predisposed immuno-inflammatory disorder driven by
HLA-B*07:
02.
We report a large family with ichthyosis bullosa of Siemens (IBS) including eight affected members spanning three generations. The classical features of the disease were consistently observed with blistering, superficial peeling of the skin, and localized lichenified hyperkeratosis mainly confined to the limbs. Phenotypic variation, however, was also observed with some individuals exhibiting unusual clinical features. Specifically, the index patient was erythrodermic at birth; she subsequently developed a widespread pustular eruption. Erythroderma is classically absent in IBS and pustulation is very unusual. She also had hypertrichosis of the limbs, as did an affected female first cousin. This has not previously been reported in IBS. Electron microscopy showed complex aggregates of keratin in the spinous and granular layers associated, in places, with remarkably little cell lysis. Sequencing of genomic DNA revealed a mutation (E493K) in keratin 2e. A review of the literature on IBS indicates that E493K is the most commonly reported mutation to date and might represent a mutational hotspot for this disease.
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