Scientists suggest a disorder that causes periods of ecstasy and depression is passed on through mothers.
PEOPLE who suffer wild swings of moods -- from ecstatic highs to melancholic lows -- have their mother to blame. At least this is what researchers at Johns Hopkins Hospital, USA, suggest: Every woman on a sprawling family tree they have drawn up passes this disorder, called the manic-depressive psychosis, to her children, but no man suffering from it does.
The researchers theorise the disorder is linked to an often-overlooked gene that hides outside the cell's nucleus, where most genes lie. Such genes are passed on to children only from the mother. Though the hypothesis of the Hopkins researchers does not fit every family tree they studied, it may be a promising place to start looking for a gene.
In fact, five other research teams around the world are involved in the quest for genes responsible for the disorder, which afflicts 2.5 million people in the US alone. Alarmingly, 20 per cent of these cases end in suicide.
The Hopkins team, led by psychiatrist J Raymond DePaulo, is hoping to find the manic-depressive genes by locating two siblings with the disorder, with one parent's side of the family normal so that it becomes clear which parent passes on the disorder. Finding a disorder-free side of the family is not easy because studies have shown manic-depressive patients tend to marry others with the disease.
So far, the Hopkins teams has screened about 2,200 families and have only 32 that fit their bill. Their target is 50 families, which they hope to achieve in 2-3 years.
However, the target is a minor problem compared to the researchers' biggest worry: there may be several genes that cause the disorder
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