Objective Human and animal studies have shown that Nav1.7 sodium channels, which are preferentially expressed within nociceptors and sympathetic neurons, play a major role in inflammatory and neuropathic pain. Inherited erythromelalgia (IEM) has been linked to gain-of-function mutations of Nav1.7. We now report a novel mutation (V400M) in a three-generation Canadian family in which pain is relieved by carbamazepine (CBZ). Methods We extracted genomic DNA from blood samples of eight members of the family, and the sequence of SCN9A coding exons was compared with the reference Nav1.7 complementary DNA. Wild-type Nav1.7 and V400M cell lines were then analyzed using whole-cell patch-clamp recording for changes in activation, deactivation, steady-state inactivation, and ramp currents. Results Whole-cell patch-clamp studies of V400M demonstrate changes in activation, deactivation, steady-state inactivation, and ramp currents that can produce dorsal root ganglia neuron hyperexcitability that underlies pain in these patients. We show that CBZ, at concentrations in the human therapeutic range, normalizes the voltage dependence of activation and inactivation of this inherited erythromelalgia mutation in Nav1.7 but does not affect these parameters in wild-type Nav1.7. Interpretation Our results demonstrate a normalizing effect of CBZ on mutant Nav1.7 channels in this kindred with CBZ-responsive inherited erythromelalgia. The selective effect of CBZ on the mutant Nav1.7 channel appears to explain the ameliorative response to treatment in this kindred. Our results suggest that functional expression and pharmacological studies may provide mechanistic insights into hereditary painful disorders.

Background Pruritus can be a distressing and even debilitating symptom for patients with cutaneous T-cell lymphoma (CTCL). To date, few studies have evaluated the pathophysiology of this symptom. Due to this, therapy for pruritus in CTCL has mainly relied on those therapies that target and treat the lymphoma. For patients living with CTCL that relapses or becomes refractory to treatment, and who continue to experience severe itch, this lymphoma-targeted treatment may not be enough to combat their pruritus. Therefore, other itch-targeted therapies are needed for use in this disease Objective Evaluate the current evidence regarding the mechanism of action and treatments for pruritus associated with cutaneous T-cell lymphoma. Methods An explicit and thorough search was restricted to all peer-reviewed literature available through MEDLINE (1950 to September 2011) and pubmed.org. Search terms used were pruritus, cutaneous T-cell lymphoma (CTCL), mycosis fungoides (MF), and Sézary Syndrome (SS). All studies that involved pruritus in either CTCL, MF, or SS were evaluated by all three authors. Results The current literature helps to identify therapies and possible mechanisms for treating patients with CTCL associated pruritus. . Limitation Most studies were pre-clinical. Only studies involving mechanisms of action or treatment were included Conclusion A guideline is necessary to assist in the treatment of pruritus in CTCL and additional studies are necessary to uncover the exact mechanism(s) of action.

Background Qualitative data suggest that pruritus is a burdensome symptom in patients with epidermolysis bullosa (EB), but the prevalence of pruritus in children and adults with EB, as well as factors that contribute to pruritus are unknown. Objective To quantitatively identify and to characterize pruritus experienced by EB patients using a comprehensive online questionnaire. Methods A questionnaire was developed to evaluate pruritus in all ages and types of EB. Questions that characterize pruritus were included, and factors that aggravate symptoms were investigated. Patients from seven North American EB centers were invited to participate. Results A total of 146 out of 216 questionnaires were completed (response rate=68%) (73 males, 73 females; median age, 20.0). Using a 5-point Likert scale (1=never, 2=rarely, 3=sometimes, 4=often, 5=always), itchiness was the most bothersome EB complication (mean=3.3). The average daily frequency of pruritus increased with self-reported EB severity. Pruritus was most frequent at bedtime (mean=3.8) and interfered with sleep. Factors that aggravated pruritus included healing wounds, dry skin, infected wounds, stress, heat, dryness, and humidity. Conclusions Pruritus is common in EB patients and can be very bothersome. Future studies will need to investigate the most effective treatments given to EB patients for pruritus.