Mutation in the novel nuclear-encoded mitochondrial protein CHCHD10 in a family with autosomal dominant mitochondrial myopathy.

Mitochondrial myopathies belong to a larger group of systemic diseases caused by morphological or biochemical abnormalities of mitochondria. Mitochondrial disorders can be caused by mutations in either the mitochondrial or nuclear genome. Only 5% of all mitochondrial disorders are autosomal dominant. We analyzed DNA from members of the previously reported Puerto Rican kindred with an autosomal dominant mitochondrial myopathy (Heimann-Patterson et al. 1997). Linkage analysis suggested a putative locus on the pericentric region of the long arm of chromosome 22 (22q11). Using the tools of integrative genomics, we established chromosome 22 open reading frame 16 (C22orf16) (later designated as CHCHD10) as the only high-scoring mitochondrial candidate gene in our minimal candidate region. Sequence analysis revealed a double-missense mutation (R15S and G58R) in cis in CHCHD10 which encodes a coiled coil-helix-coiled coil-helix protein of unknown function. These two mutations completely co-segregated with the disease phenotype and were absent in 1,481 Caucasian and 80 Hispanic (including 32 Puerto Rican) controls. Expression profiling showed that CHCHD10 is enriched in skeletal muscle. Mitochondrial localization of the CHCHD10 protein was confirmed using immunofluorescence in cells expressing either wild-type or mutant CHCHD10. We found that the expression of the G58R, but not the R15S, mutation induced mitochondrial fragmentation. Our findings identify a novel gene causing mitochondrial myopathy, thereby expanding the spectrum of mitochondrial myopathies caused by nuclear genes. Our findings also suggest a role for CHCHD10 in the morphologic remodeling of the mitochondria.

CSF-ACE activity in probable CNS neurosarcoidosis.

OBJECTIVE: To redefine the utility of CSF-ACE as a selective indicator of probable CNS neurosarcoidosis. METHODS: The diagnosis of probable CNS neurosarcoidosis required: (a) biopsy evidence of systemic sarcoidosis, (b) cortical, brainstem, and/or spinal cord deficits, (c) enhancing lesions on brain and/or spinal cord MRI, and (d) exclusion of other etiologies which could account for the neurological deficits. Radioassay measurement of CSF-ACE activity was performed in 11 patients who met our criteria for probable CNS neurosarcoidosis and 207 control patients. RESULTS: The M +/- SD for CSF-ACE activity was significantly higher (p < 0.05) for the 11 probable CNS neurosarcoidosis patients (9.5 +/- 6.9 nmol/mL/min) than for the control patients (2.9 +/- 2.7 nmol/mL/min). The optimal CSF-ACE activity discriminator value was 8 nmol/mL/min. At this value, the sensitivity and specificity of CSF-ACE activity was 55% and 94%, respectively. CONCLUSIONS: CSF-ACE activity is a useful biochemical marker of probable CNS neurosarcoidosis when brain and/or spinal cord MRI show diffuse enhancing lesions.

Causalgia: redefinition as a clinical pain syndrome.

In this report, the following criteria were used for the diagnosis of causalgia: (a) the presence of continuous, burning pain distal to a site of injury; (b) hyperalgesia and allodynia in the painful area; and (c) a traumatic event occurring proximal in the painful area and within weeks prior to the onset of pain. The McGill pain questionnaire was used to test the selected pain population for homogeneity. The scores were similar among the patients and different from the scores in other pain syndromes. It is concluded that the above criteria are sufficient to make the diagnosis of causalgia. In addition, it appears that a central nervous system abnormality best accounts for the clinical features of causalgia.