Rare and common variants in CARD14, an epidermal regulator of NF-kappaB, in psoriasis

Psoriasis is a common inflammatory disorder of the skin and other organs. We have determined that mutations in CARD14, encoding an NF-kB activator within skin epidermis, account for PSORS2. Here we describe fifteen additional rare, missense variants in CARD14, their distribution in seven psoriasis cohorts (>6,000 cases and >4,000 controls), and their effects on NF-kB activation and the transcriptome of keratinocytes. There was an excess of rare variants within CARD14 in cases versus controls (burden test p-value = 0.0015). Some variants were only seen in a single case and included putative pathogenic mutations (c.424G>A [p.Glu142Lys], c.425A>G [p.Glu142Gly]) and the generalized pustular psoriasis mutation, c.413A>C (p.Glu138Ala), that lie within the coiled-coil domain of CARD14. The c.349G>A (p.Gly117Ser) familial psoriasis mutation was present at a frequency of 0.0005 in cases of European ancestry. CARD14 variants led to a range of NF-kB activities, with putative pathogenic variants leading to levels >2.5-fold higher than wildtype CARD14. Two variants (c.511C>A [p.His171Asn] and c.536G>A [p.Arg179His]) required stimulation with TNF-a to achieve significant increases in NF-kB levels. Transcriptome profiling of wildtype and variant CARD14 transfectants in keratinocytes differentiated likely pathogenic mutations from neutral variants such as polymorphisms. Over 20 CARD14 polymorphisms were also genotyped and meta-analysis revealed association of psoriasis with rs11652075 (c.2458C>T/p.Arg820Trp; p-value = 2.1x10-6). In the two largest psoriasis cohorts, evidence for association increased when rs11652075 was conditioned on HLA-Cw*0602 (PSORS1). These studies contribute to our understanding of the genetic basis of psoriasis and illustrate the challenges faced in identifying pathogenic variants in common disease. Keratinocytes were transfected with wildtype Cardsh or one of 16 Card14 mutations (17 total samples). The cells were collected and RNA extracted to determine the effect of these mutations compared to wildtype Card14. No replicates are included.