Tardive Dyskinesia and CAG Repeat Expansions / 신경정신의학

OBJECTIVES: Much interest has recently been focused on the possibility of the involvement of unstable DNA in the etiology of schizophrenia following several publications that reported increases in frequency of large CAG repeats in affected individuals. Tardive dyskinesia(TD), an involuntary movement disorder following pharmacological treatment of schizophrenia, shares a great deal of common clinical and biological features with Huntington's disease, a representative movement disorder with CAG repeat expansions. The authors studied for a possible CAG repeat expansions in patients with schizophrenia and TD. METHODS: TD was diagnosed by the Abnormal Involuntary Movement Scale. Using repeat expansion detection(RED), a method in which a thermostable ligase is used to detect repeat expansions directly from genomic DNA, subjects with schizophrenia with/without TD(n=79/n=75) and normal controls (n=72) were studied for the presence of the CAG repeat expansions were analyzed. RESULTS: No significant size differences were detected in the(CTG)17 ligation products between schizophrenic cases and controls using RED(X(2)=2.907, df=2, p=0.234). CONCLUSIONS: This finding does not support the hypothesis that CAG repeat expansions contributes to the susceptibility for schizophrenia and TD.

A Case of Huntington's Disease without Family History Who Has Diagnosed with CAG Repeat Expansion / 신경정신의학

We report a 48-year-old female with typical symptoms of Huntington's disease, including involuntary movement, cognitive dysfunction and psychiatric symptoms such as personality change, emotional instability, persecutory ideation and depression, but without family history. The diagnosis of HD was confirmed a repetitive DNA sequence(CAG) amplification on HD locus by PCR and pAGE in this case. The DNA analysis showed that she had an allele with 43 repeat units, in the size range seen in HD chromosomes. So we reported this case with literature review.