Novel and recurrent non-truncating mutations of the MITF basic domain: genotypic and phenotypic variations in Waardenburg and Tietz syndromes.

The microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix leucine zipper transcription factor, which regulates melanocyte development and the biosynthetic melanin pathway. A notable relationship has been described between non-truncating mutations of its basic domain and Tietz syndrome, which is characterized by albinoid-like hypopigmentation of the skin and hair, rather than the patchy depigmentation seen in Waardenburg syndrome, and severe hearing loss. Twelve patients with new or recurrent non-truncating mutations of the MITF basic domain from six families were enrolled in this study. We observed a wide range of phenotypes and some unexpected features. All the patients had blue irides and pigmentation abnormalities that ranged from diffuse hypopigmentation to Waardenburg-like patches. In addition, they showed congenital complete hearing loss, diffuse hypopigmentation of the skin, freckling and ocular abnormalities, more frequently than patients with MITF mutations outside the basic domain. In conclusion, the non-truncating mutations of the basic domain do not always lead to Tietz syndrome but rather to a large range of phenotypes. Sun-exposed freckles are interestingly observed more frequently in Asian populations. This variability argues for the possible interaction with modifier loci.

Prognostic factors of paraneoplastic pemphigus.

OBJECTIVE: To identify the prognostic factors of overall survival in a series of patients with paraneoplastic pemphigus (PNP). DESIGN: Multicenter retrospective cohort study. SETTING: Twenty-seven dermatology departments in France. PATIENTS: A total of 53 patients (31 men and 22 women; median age, 59 years; age range, 30-88 years) were diagnosed as having PNP between 1992 and 2010. MAIN OUTCOME MEASURES: Overall Kaplan-Meier survival rates were estimated, and features associated with survival were assessed using univariate (log-rank test) and multivariate (Cox regression) analyses. RESULTS: The study included 53 patients with PNP. Thirty-six patients (68%) died during the study. The 1-, 3-, and 5-year overall survival rates were 49%, 41%, and 38%, respectively. The main causes of death were infections (n=21) and evolution of neoplasia (n=6). In univariate analysis, the main detrimental prognostic factors identified were erythema multiforme­like skin lesions (P=.05) and histologic keratinocyte necrosis (P=.03). None of the 5 patients with Castleman disease died during the study. After adjustment for age and sex in multivariate analysis, erythema multiforme­like skin lesions remained predictive of fatal outcome, with a 2-fold increase in death rate (hazard ratio [HR], 2.3; 95% CI, 1.05-5.03; P=.04). The prognosis of patients with PNP was even poorer when erythema multiforme­like skin lesions were associated with severe skin or mucosal involvement at presentation (HR of death, 3.0; 95% CI, 1.01-8.92; P=.049). CONCLUSION: Patients with PNP with erythema multiforme­like skin lesions and histologic keratinocyte necrosis, especially when associated with extensive lesions at presentation, are likely to have a more severe and rapid fatal outcome and should be managed very carefully.