[Clinical study and case follow-up of 61 cases of familial myasthenia gravis in 28 families].

Objective To explore the clinical features and prognosis of familial myasthenia gravis (FMG).Methods The clinical data were collected and analyzed for 61 FMG patients from 28 families from February 1998 to March 2009 at the department of neurology,First Affiliated Hospital,Sun Yat-sen University.And they were compared with 257 cases of sporadic myasthenia gravis (MG) by case-control method.Age at onset,gender,Osserman clinical classification,diagnosis,treatment,thymus imaging examination,prognosis and other family members were measured retrospectively.Results (1) The proportion of FMG in Southern China was 2.03％ and it was lower than the other countries.(2) Onset age was younger in FMG than in sporadic MG.Juvenile MG was more common in FMG than in sporadic MG (70.5％ vs 52.1％,P =0.009).(3) Ocular MG was more common in FMG than in sporadic MG (83.6％ vs 62.7％,P =0.002).(4) There was a higher proportion in FMG with thymic hyperplasia than in sporadic MG(98.3％ vs 83.7％,P =0.014).(5) Better prognosis was found in FMG than in sporadic MG.FMG patients had a higher proportion of completely stable remission than sporadic MG (24.5％ vs 11.7％,P =0.009).(6) The so-called "consistency of the same disease" could only be found in families with pure ocular diseases.If the patients with general type MG were present in the family,their pathogenetic conditions and prognosis might vary greatly.Conclusion There characteristics of FMG in south China are different from those of other countries.Their exact inheritance patterns await further explorations. Key words: Myasthenia gravis; Follow-up studies; Genetic immunity