Meiotic sex chromosome inactivation (MSCI) during spermatogenesis is characterized by transcriptional silencing of genes on both the X and Y chromosomes in mid to late pachytene spermatocytes1. MSCI is believed to result from meiotic silencing of unpaired DNA because the X and Y chromosomes remain largely unpaired throughout first meiotic prophase2. However, unlike X-chromosome inactivation in female embryonic cells, where 25–30% of X-linked structural genes have been reported to escape inactivation3, previous microarray4- and RT-PCR5-based studies of expression of >364 X-linked mRNA-encoding genes during spermatogenesis have failed to reveal any X-linked gene that escapes the silencing effects of MSCI in primary spermatocytes. Here we show that many X-linked miRNAs are transcribed and processed in pachytene spermatocytes. This unprecedented escape from MSCI by these X-linked miRNAs suggests that they may participate in a critical function at this stage of spermatogenesis, including the possibility that they contribute to the process of MSCI itself, and/or that they may be essential for post-transcriptional regulation of autosomal mRNAs during the late meiotic and early postmeiotic stages of spermatogenesis.

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Prurigo pigmentosa (PP) is a rare inflammatory dermatosis of unknown cause characterized by a predominantly truncal eruption of pruritic erythematous papules in a reticular pattern, resolving with hyperpigmentation. PP is twice as common in girls and women, and the mean age at onset is 25 years. Diagnosis of PP is challenging and is aided by characteristic histopathologic findings. We report a case of PP in a 17-year-old white boy. The eruption arose during strict adherence to a ketogenic diet.

Multiple sensory modalities were found to be abnormal in patients with erythromelalgia, with the commonest clinical abnormality being isolated heat-pain abnormality. These findings lend support to the notion that neuropathy underlies the clinical diagnosis of erythromelalgia. Future studies will explore the nature of the relationship between these sensory abnormalities and the clinical features of erythromelalgia.