Scientists discover defective gene in mentally disabled

Breakthrough at Dutch university hospital

NIJMEGEN - Children with mental disabilities, whose parents are healthy, nearly always show a spontaneous mutation in their DNA. The defect was discovered by scientists at the University Medical Centre Sint Radboud in the southern Dutch city of Nijmegen. The discovery, which now has been published in science journal Nature Genetics, could have huge consequences for diagnosing and preventing mental disability.

Radboud's researchers compared the DNA of ten mentally handicapped children with that of their parents. It appears that everyone has around 100 defects in their DNA, but that these children have the defects in unfortunate locations in their DNA, affecting the development of their brains. According to the research, the defects occur in the sperm when the father’s DNA is copied. It was already known that the chance of having a disabled child is greater with older fathers.

The discovery suggests that it will be easier to discover why a child with healthy parents has a mental disability. According to studies, parents often feel guilty fearing they might have done something before birth to affect the mental health of their child.

Prenatal examinations can determine whether subsequent children have the same defect in their DNA. The hospital hopes to offer tests to more families in the future.