EPILEPSY, LIGHT-SENSITIVITY AND LEFT-HANDEDNESS IN A FAMILY WITH MONOZYGOTIC TRIPLETS

Abstract

A family consisting of monozygotic, now 14-year-old triplets, their elder brother and parents are described. One triplet is right-handed and the other two are left-handed, as are a number of their relatives. After an analysis of the probable course in cleavage of the embryos, the hypothesis is put forward that the different handedness is due to a mirror-image mechanism in cleavage of one or possibly of both embryos. It is suggested that such a mechanism can also explain the reversed asymmetry in the papillary pattern of their hand prints in the hypothenar region. In the mother, myoclonic jerks are elicited by intermittent sunlight. During photic stimulation with the stroboscope, they are synchronous with the light flashes. The elder son has photogenic epilepsy. In his case, as in the triplets, intermittent light flashes from the stroboscope elicit a clinical seizure. It is postulated that the sensitivity to light in this family is due to a probably dominant, genetically determined cerebral dysfunction, which can be manifested clinically in different ways.