A Family Study of 50 Rem Narcoleptics

A family history was obtained from fifty REM Narcoleptic probands who were diagnosed by polygraphic sleep recordings. The overall rate of Narcolepsy and disorders of excessive sleep (DES) among the parents, siblings, and children of the probands was 9.2 per cent. The prevalence of Narcolepsy alone among the relatives was 2.5 per cent, a rate which is more than 60 times higher than in the general population. This risk for sleep disorders among the relatives of affected individuals is almost certainly an underestimate, as nearly 73 per cent of the children of the probands with a positive family history have not yet passed through the major period of risk for development of Narcolepsy (between 10 and 20 years of age). Considering our data, a recessive or a simple dominant mode of transmission of Narcolepsy or DES seems unlikely.