Cause of microcephaly discovered

Viennese researchers find gene mutation for severe developmental disorders in the brain

A mutation of the Tubb5 gene is said to be responsible for the so-called microcephaly, a pathological reduction in size of the head, according to a study by the Vienna Research Institute for Molecular Pathology (IMP). About one in ten thousand children are born with the severe developmental disorder, which results in severe mental impairment.

Gene mutation interferes with the stem cell pool and nerve cell migration The reduced brain growth can be caused by environmental stress such as alcohol abuse, but also by viral infection, for example rubella. A genetic defect is also often a trigger for microcephaly. The IMP biologist David Keays and the doctoral student Martin Breuss have now successfully identified a gene that is said to be responsible for the insidious disease.

Tubb5 is said to lead to impaired brain growth as a result of mutations. The researchers came to this conclusion while, in cooperation with scientists from Monash University in Australia, targetedly disturbed the brains of unborn mice with Tubb5. As a result, brain impairment developed in the mice. The stem cell reservoir was changed and the migration of the nerve cells was impaired. Both the unimpeded replenishment of the nerve cells from the stem cell pool and their positioning in the cerebral cortex are crucial for the development of the brain.

Tubb5 mutation allows conclusions to be drawn about evolution As the researchers report in the current issue of the online journal "Cell Reports", the new findings are also interesting from an evolutionary point of view, because the number of neurons relative to body weight and their positioning in one are strong folded brains are related to the evolution from monkey to primate and on to human.

French doctors at the Sorbonne in Paris checked whether the new findings can also be transferred to people. Three children with a Tubb5 mutation could be identified among the patients suffering from microcephaly. "Our work is a good example of how knowledge from basic research on animal models can be transferred to human medicine," explains Keays. The discovery of this causal relationship is important for medical professionals in order to provide genetic counseling to parents with children with developmental disorders. Targeted therapy may also be developed in the long term. (fp)

Read also on microcephaly:
Deciphered genetic defect of rare short stature

Photo credit: Gerd Altmann /

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