Limb girdle and facial weakness in female carriers of X-linked myotubular myopathy mutations

Although X-linked myotubular myopathy (XLMTM) is a recessive disorder, hete rozygous female carriers of MTM1 mutations may present with limb girdle and facial weakness. It is proposed that manifesting heterozygote females with XLMTM have a skewed pattern of X-chromosome inactivation. However, skewed X-chromosome inactivation was not detected in either the lymphocyte or musc le DNA of a woman who presented with limb girdle/facial weakness and was fo und to be heterozygous for the R224X mutation.