| Rh-factor
blood incompatibility increases risk for schizophrenia Rh-positive infants born to Rh-negative mothers are twice as likely to develop schizophrenia in young adulthood as children who are genetically compatible for the blood antigen, according to an article in the December issue of the American Journal of Human Genetics. The researchers’ mathematical model was able to determine that the correlation was due directly to genetic incompatibility at the Rh gene (called Rhesus D factor gene) and not to one of two different possibilities, effect of a different gene located near the Rh gene or a direct maternal effect. "Previous studies reported a link between mothers and infants who are Rh-incompatible and a higher rate of schizophrenia in the children later in life," explained Dr. Christina Palmer, lead author of the study. "Our research is the first to take a genetic approach to examining this increased risk." When a fetus is Rh-positive and the mother Rh-negative, the maternal immune system can become sensitized to the antigen and cause fetal hemolysis. Hypoxic conditions in the fetal brain can result, and eventually, jaundice. "In heavy doses, oxygen deprivation and jaundice can cause serious brain damage," noted Palmer. "Even more subtle consequences may set the stage for abnormal brain development and schizophrenia down the road." "Many studies have shown that mothers of children who develop schizophrenia experience a higher rate of fetal distress and obstetric complications," said Palmer. "We hypothesized that stressors produced by Rh incompatibility in the prenatal environment - --such as oxygen deficiency to the brain --- could predispose a child for schizophrenia later in life." To test their hypothesis, the researchers
mapped out the genetic make-up of 181 Finnish families in which
at least one family member had been diagnosed with schizophrenia.
Except for three cases, all of the children in the sample were born
before the introduction of prophylaxis in 1970. "The next important step will be
to look at Rh incompatibility in people born after 1970 to test
whether prophylaxis has reduced their risk of schizophrenia."
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