The British Journal of Psychiatry 133: 68-72 (1978)
© 1978 The Royal College of Psychiatrists
Ancestral secondary cases on paternal and maternal sides in bipolar affective illness
GF Johnson and MM Leeman
An analysis of the distribution of ancestral secondary cases of affective
illness in families of patients with bipolar manicdepressive disorder was
undertaken. Twenty probands with at least two affectively ill second degree
relatives were available for study. Probands with both parents affected
were excluded. The distribution of unilateral to bilateral pairs of all
affected relatives, both excluding and including parents, of probands
showed no significant differences from that expected in polygenic
inheritance. However, separation into bipolar family history, positive or
negative, showed significant differences from the expected ratio of
unilateral to bilateral pairs in a bipolar family history positive group
consistent with a single dominant gene inheritance.