Update of cylindromatosis gene (CYLD) mutations in Brooke-Spiegler syndrome: novel insights into the role of deubiquitination in cell signaling.

Germline mutations in the cylindromatosis (CYLD) gene have been described in families with cylindromas, trichoepitheliomas, and/or spiradenomas. Brooke-Spiegler syndrome (BSS) is the autosomal dominant predisposition to skin appendageal neoplasms including cylindromas, trichoepitheliomas, and/or spiradenomas. We review the clinical features, molecular genetics, and the animal models of BSS. To date, a total of 51 germline CYLD mutations have been reported, occurring in exons 9-20, in 73 families with diverse ethnic and racial backgrounds. Of 51 mutations, 86% are expected to lead to truncated proteins. The seven missense mutations reported to date occur only within the ubiquitin (Ub)-specific protease (USP) domain of the CYLD protein and most are associated exclusively with multiple familial trichoepithelioma (MFT). CYLD functions as a tumor suppressor gene. CYLD encodes a deubiquitinating (DUB) enzyme that negatively regulates the nuclear factor (NF)-kappaB and c-Jun N-terminal kinase (JNK) pathways. CYLD DUB activity is highly specific for lysine 63 (K63)-linked Ub chains but has been shown to act on K48-linked Ub chains as well. In 2008, the CYLD USP domain was crystallized, revealing that the truncated Fingers subdomain confers CYLD's unique specificity for K63-linked Ub chains. Recent work using animal models revealed new roles for CYLD in immunity, lipid metabolism, spermatogenesis, osteoclastogenesis, antimicrobial defense, and inflammation.

The folliculin mutation database: an online database of mutations associated with Birt-Hogg-Dubé syndrome.

The folliculin gene (FLCN), also known as BHD, is the only known susceptibility gene for Birt-Hogg-Dubé syndrome. BHDS is the autosomal dominant predisposition to the development of follicular hamartomas, lung cysts, spontaneous pneumothorax, and/or kidney neoplasms. To date, 53 unique germline mutations have been reported. FLCN mutation detection rate is 88%. FLCN encodes a predicted 579-amino acid protein, designated folliculin that is highly conserved between humans and homologs in mice, Drosophila, and C. elegans. We developed the first online database detailing all FLCN variants identified in our laboratory and reported in the literature. The FLCN database applies, and assists researchers in applying HGVS nomenclature guidelines. To date, the FCLN database includes 84 variants: 53 unique germline mutations and 31 SNPs. The majority of FLCN germline mutations are predicted to produce a truncated folliculin, resulting in loss of function. The FLCN mutations consist of: 45% (24/53) deletions, 32% (17/53) substitutions (10 putative-splice site, 5 nonsense, and 2 missense), 15% (8/53) duplications, 6% (3/53) insertion/deletions and 2% (1/53) insertions. The database strives to systematically unify current knowledge of FLCN variants and will be useful to geneticists and genetic counselors while also providing a rapid and systematic resource for investigators.

Prior history of non-melanoma skin cancer is associated with increased mortality in patients with chronic lymphocytic leukemia.

We investigated whether a previous diagnosis of non-melanoma skin cancer among chronic lymphocytic leukemia patients is a predictor of poor outcome. Using the Swedish Cancer Registry, we conducted a population-based study to evaluate the survival patterns among chronic lymphocytic leukemia patients with and without non-melanoma skin cancer. Cox proportional hazards regression models were used and Kaplan-Meier curves were constructed. Of a total of 12,041 chronic lymphocytic leukemia cases identified, 236 cases, including 111 squamous cell cancer, had a prior history of non-melanoma skin cancer. Chronic lymphocytic leukemia patients with a prior history of non-melanoma skin cancer had a 1.29-fold (95% CI 1.10-1.52; p=0.0024) increased risk of dying; and those with a history of squamous cell cancer had a further elevated 1.86-fold (95% CI 1.46-2.36; p<0.0001) risk of dying. Kaplan-Meier plots showed that patients with a history of non-melanoma skin cancer, particularly those with squamous cell cancer, had significantly poorer survival than chronic lymphocytic leukemia patients without non-melanoma skin cancer (p<0.0001; log-rank test). Non-melanoma skin cancer may be a novel clinical predictor of worse chronic lymphocytic leukemia outcome.

Cutaneous appendageal carcinoma incidence and survival patterns in the United States: a population-based study.

OBJECTIVE: To examine incidence patterns of patients diagnosed as having cutaneous appendageal carcinoma (CAC). DESIGN: Population-based study using the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute data from 1978 through 2005. PARTICIPANTS: A total of 1801 subjects from SEER 16 registries (2001-2005) for incidence analyses, 2228 from SEER 9 registries (1987-2005) for trend analysis, and 1984 subjects (1992-2004) for survival analysis. MAIN OUTCOME MEASURE: Incidence rates (IRs) per 1 million person-years according to anatomic site, race, sex, age, and histologic type. RESULTS: Cutaneous appendageal carcinomas are uncommon (age-adjusted IR, 5.1 per 1 million person-years), with the IR among men statistically significantly higher than women (6.3 vs 4.2, respectively; male to female IR ratio 1.51; P < .001). Hispanic whites (IR, 3.7), blacks (IR, 3.5), and Asian/Pacific Islanders (IR, 2.5) all had significantly lower IRs than non-Hispanic whites (IR, 5.7) (P < .001). Apocrine-eccrine carcinoma overall was the most common category (IR, 2.6), and the IR was highest among non-Hispanic white (IR, 2.8) compared with other ethnic/racial groups (P < .001). Cutaneous appendageal carcinomas IRs rose 100-fold with age, from 0.37 among those aged 20 to 29 years to 37.3 among those 80 years or older. From 1978-1982 to 2002-2005, the CAC IRs increased 150%, from 2.0 to 5.0; the apocrine-eccrine carcinoma and the sebaceous carcinoma IRs rose 170%, from 1.0 to 2.7, and 217%, from 0.6 to 1.9, respectively. Five-year relative survival rates overall were 99% for localized and 43% for distant disease. CONCLUSIONS: Cutaneous appendageal carcinomas are rare tumors with IRs that vary by sex and racial/ethnic group. Cutaneous appendageal carcinoma IRs are increasing in the United States, especially for sebaceous carcinoma, perhaps related to improved recognition and classification, but factors such as UV exposure and immunosuppression may also play a role.