Familial subacute sclerosing panencephalitis associated with short latency.

The familial recurrence of subacute sclerosing panencephalitis is rare. The study of such cases and a comparison of intrafamilial with sporadic cases of subacute sclerosing panencephalitis may shed light on important pathogenetic factors. We report on the occurrence of subacute sclerosing panencephalitis in two brothers from rural India, who contracted measles infection simultaneously at ages 3 and 11 years. They developed subacute sclerosing panencephalitis 21 and 37 months later, respectively. A diagnosis of subacute sclerosing panencephalitis was based on history, electroencephalographic changes, and significantly raised levels of cerebrospinal-fluid anti-measles virus immunoglobulin G. A comparison of intrafamilial with sporadic cases of subacute sclerosing panencephalitis revealed that latency in familial subacute sclerosing panencephalitis involved a median of 6.4 years (range, 1.0-10.9), significantly (P < 0.05) shorter than in sporadic cases with a median of 9.7 years (range, 2.7-23.4). This difference was because of significantly later infection with measles virus and an earlier onset of encephalitis. We describe the first siblings affected by subacute sclerosing panencephalitis from the Indian subcontinent. We confirmed a more rapid manifestation of subacute sclerosing panencephalitis after measles virus infection in intrafamilial compared with sporadic subacute sclerosing panencephalitis.