The clinical features, course, and presence of acetylcholine receptor antibody (AChRAb) were reviewed in 25 congenital (CMG) and 30 juvenile (JMG) cases of myasthenia gravis seen at Hacettepe University, Department of Paediatric Neurology, Ankara, Turkey. The age range of onset showed overlap: birth to 4 years for CMG, and 1.5 to 15 years for JMG. Parental consanguinity was present in 15 (60%) of CMG and only 3 (30%) of JMG patients. Motor development was delayed in 9 (36%) CMG infants and in 3 (10%) JMG patients. Initial symptoms were ocular in equal frequency for CMG (44%) and JMG (53%). After 1 year follow-up, only 4 (16%) CMG patients had ocular only involvement, 19 (76%) having progressed to ocular and bulbar or generalized weakness. Symptoms were limited to ocular muscles in 47% of JMG patients after 1 year. Unlike CMG, JMG patients showed spontaneous remissions in 20% and myasthenic crises in 33%. Good response to anticholinesterase drugs was more frequent in JMG than CMG (63 versus 41%). AChRAbs were present in 9 (34%) of JMG patients, all were girls with a later disease onset (>11 yrs) than antibody-negative cases. Pure ocular forms of MG were more often seronegative. None of the antibody-positive cases were in remission. The response to treatment was not significantly different between seropositive and negative cases. 
COMMENT. In this series of childhood onset myasthenic patients, the proportion of congenital cases was much larger than previously reported. Facial muscle involvement and malformation often described in congenital cases was not alluded to in the above report. (see Progress in Pediatric Neurology I and II, PNB Publ, 1991 & 1994). Family and developmental histories, severity and distribution of weakness, and response to therapy are supportive criteria for the differentiation of congenital and juvenile cases.