Clinical Significance of CTG Repeat Expansion in Korean Myotonic Dystrophy Patients

BACKGROUND: Myotonic dystrophy is the most common type of muscular dystrophy affecting adults, associated with the expansion of triplet repeat DNA sequences. A hallmark of the inherited disease with trinucleotide repeat DNA expansion is the clinical and genetic anticipation. The copy numbers of the CTG repeat are known to be related to the severity and the onset age of clinical symptoms. METHODS: The copy numbers of the CTG repeats were determined using PCR amplification and Southern blotting. The clinical manisfestations of 34 patients from 14 families who had the CTG repeat expansion were evaluated based on the muscular disability rating scale and the electrophysiological study. RESULTS: There was a significant positive correlation between the clinical scores and the size of the amplification of trinucleotide repeat, and a negative correlation with the age of onset. In 9 patients with copy numbers of CTG repeats between 61 and 100, 8 cases were asymptomatic and myotonic discharges were not seen in 71% of patients. Larger expanded bands, earlier onset, and worse symptoms were evident with each successive generation. CONCLUSIONS: Molecular genetic analysis with CTG repeat expansion might be useful in the detection and the genetic counseling of myotonic dystrophy patients.

One case of Subacute Sensory Neuropathy Associated with Primary Sjogren's Syndrome

Subacute sensory neuropathies associated with primary Sjogren's syndrome have been reported rarely. We describe a woman with primary Sjogren's syndrome who developed a widespread, pure sensory neuropathy with a subacute onset. An electrophysiological study showed the typical absence or decreased amplitude of sensory nerve action potentials (SNAPs). A sural nerve biopsy showed a loss of large myelinated fibers and axonal degeneration without inflammation. The clinical course of long-standing subacute sensory neuropathy, the biopsy-documented axonal degeneration, and the neurophysiological findings suggest involvement of the dorsal root ganglia.

Nerve Conduction studies of Sunacute combined Degeneration

OBJECT: There have been some controversies about the nature of peripheral neuropathy in patients with subacute comblned degeneration. Mayer concluded that the neuropathy was essentially demyelinating. And other reports which were based on pathologic or electrophyslological filldings have been saying axonopathy. We tried to find the nature of perlpheral neuropathy by doing conventional nerve conduction studies in 19 patients with subacute combined degeneration. SUBJECT AND METHOD: We included 19 patients with subacute combined degeneration, who were diagnosed by decreased serum vitamin B12(200pg/ml) and abnormal neurologic symptoms and/or signs. The patients were between 26 and 86 years of age. Eleven of them were male. We performed conventional nerve conduction studies Including H-reflex, When nerve conduction parameters deviated by more than 2SD from the normal mean value, they were consider as abnormal. RESULTS: nerve conduction studies were abnormal in 13/19. 11/13 with abnormal nerve conduction studies showed the pattern of peripheral polyneuropathy. Ten of them showed decreased amplitudes of sensory nerve action potentials or compound nerve action potentials with/wlthout mild slowing of nerve condcution. The abnormalities of the three patients with nerve conduction parameters of demyelinating range were confined to the distal segments of the median nerves. CONCLUSION: We thought that the results of the nerve conduction studies of our cases were compatible with axonopathy rather than demyelinopathy as a principal ]esion of the peripheral nervous system.

Central Neurofibromatosis Associated with Atypical Choroid Plexus Calcification

The computed tomographic findings in 5 patients with the central neurofibromatosis were reviewed. Atypical choroid plexus calcification was evident in 3 of 5 patients in the anterior half of lateral ventricle, foramen of Monro and third ventricle. The cause of this abnormal calcification is unknown yet, but it may have the diagnostic significance for central neurofibromatosis.