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Experiments on Zebrafish helped a family understand the cause of a rare genetic disorder in three of its members, which remained unknown until now.

The study began when a young boy with symptoms like restricted growth, recurrent fever and seizures was presented to researchers. The boy also had shunted head growth, known as microcephaly. The boy's uncles also shared symptoms which led researchers to conclude that the X chromosome in the boy and his uncles may have suffered a mutation.

"Using this clue, the scientists tracked down a mutation carried only by the affected males and their mothers, within a gene called RPL10 located on the X-chromosome. This gene encodes part of the ribosome, which is a central piece of the molecular machinery that translates the genetic code into proteins," a press release said.

The next step was to find out if the mutation was actually causing disease. This could have been easily done if similar cases were found in other families. However no such data was available for the researchers. Therefore, they decided to test their hypothesis in a model organism.

With the help of Duke University researchers, they replaced Zebrafish DNA with normal human DNA to find that it promoted normal growth of the head. When mutant human DNA replaced normal Zebrafish DNA, microcephaly resulted.

"This was a one-of-a-kind family affected by a disorder that no one had ever seen before. But they are not alone. Many others suffer from ultra-rare genetic diseases, and one of the best ways of finding answers for these families is for clinicians and model organism researchers to join forces," said Erica Davis from the Center for Human Disease Modeling at Duke University.

Compared to lab rats and mice, Zebrafish are easier to cultivate and maintain. They are useful as they 70 percent of human protein coding genes can be found to have equivalents in Zebrafish. 

The findings have been published in the journal Genetics.