A familial form of convulsive disorder with or without mental retardation limited to females: extension of a pedigree limits possible genetic mechanisms.

An unusual pedigree of female-limited seizures with or without mental retardation is updated. The disorder was first detected in a large cohort of women whose fathers were brothers, and affected women had previously transmitted the disorder. Four brothers of affected females have now had five unaffected daughters while four affected women have had four affected and one unaffected daughters and two unaffected sons. This unusual transmission pattern is discussed in terms of germ-line imprinting, neuronal sexual differentiation, and the generally higher risk of seizures seen when the mother, rather than the father, is affected.