[Clinical characteristics of myasthenia gravis with dysphonia as the initial symptom].

OBJECTIVE: To identify clinical features and diagnostic tests that would alert the otolaryngologist to consider myasthenia gravis (MG) in the differential diagnosis of dysphonia, we reviewed the clinical characteristics of MG whose initial symptom is dysphonia. METHODS: 31 patients who presented with dysphonia as their initial and primary complaint are reported, their symptoms and signs are observed and analyzed. RESULTS: Patients with dysphonia as their initial symptom of MG may complain of vocal fatigue, difficulty sustaining or projecting their voices, breathy voice or intermittent hoarseness. These symptoms are characterized by fluctuating weakness and abnormal fatigability. Flexible fibroendoscopic examination revealed that patients had incomplete adduction of the vocal folds, fatigue of the tensors of the vocal fold, incomplete glottic closure, vocal cord paralysis, saliva pooling over the bilateral or unilateral pyriform sinus. Neostigmine test revealed dramatic improvement in all patients. Serum levels of anti-Ach-R antibodies were tested in 19 cases, only 5 cases were abnormality. All patients had improved after treatment CONCLUSIONS: Voice changes can be the first sign of early MG. Based on fluctuating weakness or weak voice at the end of the day, a positive neostigmine test, significantly higher circulating antibody to acetylcholine receptor, a diagnosis of MG could definitively be made.

[HLA-DQB1 allele polymorphism and clinical characteristics of 15 familial myasthenia gravis cases in north China].

OBJECTIVE: To investigate the relationship between the HLA-DQB1 allele polymorphisms and the clinical features of 15 familial myasthenia gravis (MG) cases in north China. METHODS: By polymerase chain reaction-sequence specific primers (PCR-SSP), the HLA-DQB1 gene polymorphisms were determined in 64 MG patients (15 familial and 49 sporadic) and 52 healthy individuals as control group. The clinical characteristics of 15 familial MG patients and 49 sporadic were analyzed. The measurement data was analyzed by t test and enumeration data by chi-square test. RESULTS: The frequency of DQB1*0501 was significantly increased in familial MG, especially in the ocular type, compared with sporadic MG (P<0.05, OR=3.08) and healthy controls (P<0.01, OR=4.439). Comparing with healthy controls, the frequency of DQB1*0301/4 was increased (P<0.05, OR=2.56), while the frequency of DQB1*0601 was significantly decreased (P<0.05, OR=0.33) in sporadic MG. The familial patients had an early age of disease onset, but less severity and good prognosis. CONCLUSION: The familial MG has distinctive clinical features. DQB1*0501 allele is positively related to the genetic susceptibility to familial MG patients in north China, especially to the ocular type. DQB1*0301/4 allele is positively related to the pathogenesis of sporadic MG. DQB1*0601 may be a protecting allele for sporadic MG. The phenotype of MG may be the result of interaction of hereditary defects and environmental factors. The familial MG may be different from sporadic patients in genetic immune mechanism.