The potential role of genetic factors in the etiology of posttraumatic
and alcohol-associated seizures was studied in 289 male patients with
recurrent seizures and in 174 individuals who had never experienced a
seizure. The incidence of seizures in first-degree relatives of proba
nds was compared with that in relatives of unaffected individuals. Rel
atives of patients with alcohol-associated seizures had a rate ratio o
f 2.45 [95% confidence interval (CI) 1.41-4.25], whereas no excess inc
idence was noted among relatives of posttraumatic epilepsy patients (r
ate ratio 1.20, 0.64-2.25 CI). Relatives of probands with both anteced
ents showed an intermediate rate ratio of 1.72 (0.92-3.20 CI). Among p
robands with alcohol-associated seizures, the rate ratio of 2.05 for p
atients with alcohol-related seizures (i.e., spontaneously occurring s
eizures in association with chronic alcohol abuse) was slightly higher
than that of 1.85 for probands with alcohol withdrawal seizures. Trau
ma severity had a slight impact on the incidence of affected relatives
; patients with severe head injuries had a rate ratio of 0.73 and prob
ands with milder trauma had a rate ratio of 0.99. The results indicate
a limited, if any, role of genetic predisposition in development of p
osttraumatic seizures. Alcohol-related seizures, however, showed famil
ial aggregation of unprovoked seizures, suggesting an involvement of g
enetic factors in the origin of such seizures.