Three cases of hereditary myoclonic epilepsy have been observed among ten siblings in a Negro family. Electroencephalograms of the parents, three normal siblings and two of the three affected siblings have been recorded and all show abnormalities of a similar type. These are of a generalized nature revealing no focal damage. This type of abnormality has been observed in an affected male and two normal siblings by Watson and Denny-Brown.
The autosomal recessive mode of inheritance observed in the present study is consistent with the transmission most frequently reported in myoclonic epilepsy. We believe that abnormal electroencephalographic patterns are associated with this gene and that these patterns may be useful in the detection of heterozygous carriers.