Pyoderma gangrenosum, acne and ulcerative colitis in a patient with a novel mutation in the PSTPIP1 gene.

BACKGROUND: Pyogenic sterile arthritis, pyoderma gangrenosum and acne (PAPA) syndrome is a rare hereditary, autosomal dominant, auto-inflammatory disease caused by mutations in the PSTPIP1 gene, which encodes proline-serine-threonine phosphatase interacting protein 1. The fact that PSTPIP1 is involved in immune regulation provides a rationale for treatment of this rare disease with interleukin (IL)-1 signalling blocking agents. AIM: We investigated a 33-year-old man with a long-standing history of ulcerative colitis, severe acne and recurrent skin ulcerations, and a 3-year history of a recalcitrant pustular rash. METHODS: We used direct sequencing to search for mutations in the PSTPIP1 gene. RESULTS: Examination of biopsies obtained from pustules and skin ulcers revealed folliculitis and ulceration with a diffuse neutrophilic dermal infiltrate, consistent with a diagnosis of pyoderma gangrenosum. Because of the known association of acne and pyoderma gangrenosum in PAPA syndrome, we determined the entire coding sequence of the PSTPIP1 gene, and identified a hitherto unreported heterozygous mutation predicted to alter a highly conserved residue (p.G403R) and to be damaging to the protein function. Based on this finding, we initiated treatment with a human IL-1 receptor antagonist, anakinra, which led to a dramatic improvement in the patient's condition. CONCLUSIONS: We describe a novel mutation in PSTPIP1 resulting in pyoderma gangrenosum, acne and ulcerative colitis. This novel constellation of clinical manifestations, which we term 'PAC syndrome', suggests the need to regroup all PSTPIP1-associated phenotypes under one aetiological group.

Epidermolytic palmoplantar keratoderma caused by activation of a cryptic splice site in KRT9.

Epidermolytic palmoplantar keratoderma (EPPK) is caused by mutations in KRT9 and less often, KRT1. All known mutations in KRT9 have been found in regions of the gene encoding the conserved central α-helix rod domain. In the present study, we investigated the molecular basis of EPPK in a patient of Ashkenazi Jewish origin. The patient was found to carry a novel missense mutation in KRT9, resulting in the substitution of a poorly conserved leucine for valine at position 11 of the amino acid sequence. Despite its unusual location, the mutation was shown to be pathogenic through activation of a cryptic donor splice site, resulting in the deletion of 162 amino acids. The present data indicate the need to screen keratin genes in their entirety, as mutations altering domains of lesser functional importance may exert their deleterious effect at the transcriptional level.